Pinned Repositories
2732-to-2532
2732 to 2532 EPROM adapter
27C512E-TO-2532S-V1R1.20.APRIL.2019
TheLittleEngineers.org-27C512E-TO-2532S-V1R1.20.APRIL.2019 27C512 E.P.R.O.M. TO TMS2532 SOCKET CONVERTER. (C) 20 April 2019 and 01 June 2019 by: Robert Allen Turner http://www.TheLittleEngineers.org/ https://github.com/TheLittleEngineers This product is intended to allow a 27512 or 27C512 EPROM to be placed into a TMS2532 EPROM socket. The 27512 is divided into 16 banks of 4Kbytes via the four jumpers at the bottom of the socket. Released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License, 01 June 2019 In Memory of my Father, Robert Embry Turner, 1945 - 2019. Rest In Peace. I LOVE YOU DAD! Archive name: "TheLittleEngineers.org-27C512E-TO-2532S-V1R1.20.APRIL.2019" This is an update to the "TheLittleEngineers.org-27C512E-TO-2532S-V1R0.20.APRIL.2019" repository which resides at this url: https://github.com/TheLittleEngineers/27C512E-TO-2532S-V1R0 This update was made due to the fact that I was not very pleased with the initial Printed Circuit Boards that resulted from the original design. Although functional, the production of the Printed Circuit Boards was inconsistent between different manufacturers. This was due to a problem in the dimension layer of the original design and so I have created this new design to eliminate the inconsistencies. This version should provide much better results.
CC2-32K-EPROM-CARTRIDGE-2012-V2R0
This is an EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1,2 and 3. It will probably work with the Dragon Data Dragon computers as well. It uses a 27C512 EPROM jumper selected as two 32K banks. The CoCo 1, 2 and Dragon can only access the first 16K of each bank. The CoCo 3 can access the entire 32K of each bank, minus the 0xFFnn I/O and Vector page. The project has been shared to github: https://github.com/TheLittleEngineers/CC2-32K-EPROM-CARTRIDGE-2012-V2R0. Many other similar cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. The project is released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License [https://creativecommons.org/licenses/by-sa/4.0/] github: https://github.com/TheLittleEngineers/CC2-32K-EPROM-CARTRIDGE-2012-V2R0 OSHpark: https://oshpark.com/shared_projects/wl9Kmtit Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1
CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1 is the 32K Version of the CoCoDragon-8K-EPROM-Cartridge-CC1-8KEC-0001.1 - It is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. This was one of the very first things that my nephew created when he was teaching himself electronics and computer design - it works, but could be better. He made and sold about 30 or so of these almost ten years ago. The design was meant to be as small as possible so as to fit entirely inside the cartridge Program Pak port and was useful for DriveWire or CoCoNet. It uses a 27256 EPROM. Updated to version 0001.1 on 5 May 2019 by “Ankle” Bob and released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License [https://creativecommons.org/licenses/by-sa/4.0/] - there is definitely a lot of room for improvement and “Little John” made many improved versions which will be shared as I get more time to do so. There is a github page for this project here: https://github.com/TheLittleEngineers/CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1 and an OSHpark page here: https://oshpark.com/shared_projects/mqju7EpZ Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
CoCoDragon-CC2-32K-EPROM-CARTRIDGE-2012-V1RA
CC2-32K-EPROM-CARTRIDGE-2012-Version-1-Revision-A-07.02.2012 is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order.
CoCoDragon-CC2-32KEC-V1RA
CC2-32K-EPROM-CARTRIDGE-Version-1-Revision-A-01.06.2013 is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. There is a GitHub Page here:
CoCoDragon-MultiPakInterface-CC-Multi-Pak_Version_1.2
CoCoDragon-MultiPakInterface-CC-Multi-Pak_Version_1.2 - This is a clone of the Tandy Radio Shack TRS-80 Color Computer Multi-Pak Interface #26-3024 (which should also be compatible with the #26-3124). This was designed by my nephew "Little John" and his father "Big John" (J.R. as he is known to me). I have made very minor modifications to it. "Little John" designed this thing to work with ATX Power Supplies, which makes sense I guess - that is the most common power supply in the whole of the known universe. Please note that I have not yet tested this but I am ordering boards and will post an update after initial testing has been completed.
CoCoDragonFlexiMIDI-V1R2
CC-FlexiMIDI-V1R0-03.09.2009 and CC-FlexiMIDI-V1R1-03.09.2009 : Updated to CC-FlexiMIDI-V1R2-12.29.2019 on December 29, 2019 ================================ BACKGROUND: CC-FlexiMIDI-V1R0-03.09.2009 - A Hardware M.I.D.I. Interface Program Pak Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2 and 3, including clones and compatibles (Tano Dragon 64, Dragon Data D32, D64 and D200, Tandy Data Products TDP-100, etcetera) by "Little" John Eric Turner and his father "Big" John Robert (J.R.) Turner. Copyright 09 March 2009. Originally released as Open-Source Hardware on March 9, 2009. Subsequently released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License on 21 May 2019. ENJOY! Note that the original design is crap, however, a debugged version is forthcoming from "Uncle" Robert "The R.A.T." Allen Turner. CC-FlexiMIDI-V1R0-03.09.2009 has been updated to CC-FlexiMIDI-V1R1-03.09.2009 by R.A. Turner on May 21, 2019, just over ten years after the initial release of Version 1, Revision 0. Version 1, Revision 1 is Copyright (C) 2019 by the above mentioned parties and is released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License on 21 May 2019. =============================== DESCRIPTION: This project is an updated version of the "CC-FlexiMIDI-V1R0-03.09.2009", a hardware MIDI Interface Card for the Tandy Radio Shack TRS-80 Color Computer 1,2 and 3, Dragon Data Dragon D32, D64 and D200, Tandy Data Products TDP-100, Tano Dragon 64 and other clones and compatibles. The original "CC-FlexiMIDI-V1R0-03.09.2009" was designed by my nephew, "Little John", on March 8-9, 2009 as a learning excercise. He was teaching himself to use E.A.G.L.E. in order to design products for the TRS-80 Color Computer line of computers, with the help of his father, my brother, "Big John" or "J.R." as he is known to me. The "CC-FlexiMIDI-V1R0-03.09.2009" was among his very first (learning the art of circuit design) works. It is a terrible design only because he knew nothing about circuit design at the time and it does not appear that his father, "Big John" (J.R.) offered any input in regards to this particular design. I, "Uncle" Robert "The R.A.T." Allen Turner, have decided to polish up the design a bit and lay out a manufacturable Printed Circuit Board which I will release under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License. As such, I will analyze "Little John's" original design and then provide my improved version. The original "CC-FlexiMIDI-V1R0-03.09.2009" design files, as provided by "Little John" and his father (J.R.) are contained in the "Original (Deprecated)" folder of this archive and should be referenced for this initial analysis of the design. ================================ ANALYSIS OF ORIGINAL DESIGN: Load up the "CC-FlexiMIDI-V1R0-03.09.2009.sch" schematic file and have it handy for this discussion. Starting with Page 1 of the schematic, we see the expected cartridge (program pak) plug followed by an oddly interesting series of "purported" interrupts, labeled IRQ0* and IRQ1* (the "*" indicates low-level triggering, or active low). These "Interrupts", IRQ0* and IRQ1* appear to go, through disable jumpers, to Pins 1 and 2 of the CoCo Cartridge (Program PAK) Connector. This is both ODD and INTERESTING because Pins 1 and 2 of that connector are -12V and +12V, respectively, on ALL CoCo 1's, TDP-100's and ALL Multi-Pak Interfaces. Both of these pins are +12V on the Dragon computers. Those self-same pins, however, are NOT connected to anything on ANY stock, unmodified, CoCo 2 or 3 computers. I am thus forced to draw the following conclusion: "Little John" apparently allowed for using Pins 1 and 2 of a CoCo 2 or 3 Cartridge Slot to connect to any desired interrupt within the CoCo 2 or 3. That is, a CoCo 2 or 3 might be modified to connect Pins 1 and/or 2 of the Cartridge Slot to any of the CPU Interrupts, the PIA Interrupt (CART*), G.I.M.E. (A.C.V.C.) Interrupts (CoCo 3 only), etcetera. This is an UNECCESSARY feature of the "FlexiMIDI" design and my initial inclination was to omit it from the design. However, since there are jumpers that allow these "hacked in" custom interrupts to be disabled (removed) via JP1 and/or JP2 or connected together (wire or'ed) via JP3, I have decided to leave them in the design should anyone be so inclined as to use this custom interrupt scheme for experimentation or otherwise. Also on Page 1 is a fairly standard RESET switch which I would imagine could prove to be quite convenient but potentially problematic if the device is plugged into a Multi-Pak Interface (RESET* is buffered in a single direction in the M.P.I. and should not be triggered from any cartridge plugged into the M.P.I.), Power ON L.E.D. (which I assume might be quite distracting) and some pull-up resistors for the interrupts, custom and legit. Lastly, there is a 220uF Electrolytic Capacitor for Vcc (+5V) filtering. Ideally, a low ESR Electrolytic should be used, however, paralleling a 220uF Electrolytic with a .1uF Ceramic Disc should provide approximately the same result as a single Low ESR type. Moving on to Page 2, we see a crystal oscillator comprised of three inverters, three resistors and a crystal rated at 1 to 2 MHz. The third inverter actually acts as a buffer and "shaper". Schmitt Trigger inverters are used, although this is not actually necessary it does provide a nice, sharp square wave. Without the hysteresis provided by the schmitt triggers the waveform would appear quasi-sinusoidal at the crystal frequency if viewed on an oscilloscope, but would still function just fine. The output of that third inverter, the buffer stage, is fed into a pair of toggling D type Flip-Flops which provide a divide by two output and a divide by four output, either of which may be selected by jumper JP4. Ideally, we want a solid 500KHz squarewave as the ACIA Clock (which "Little John" labeled "MIDICLOCK" or "MIDICLK"). If a 1MHz crystal is used we would place JP4 on Pins 1 and 2. With a 2MHz crystal we would connect JP4 Pins 2 and 3. This is flexible in that it allows the use of either a 1MHz or 2MHz crystal, whichever might be handy. In my case, and for the redesign, I have a large stock of 16MHz half-can oscillators and so this is what I will be using in the redesign. The 500KHz then, will be derived from the 16MHz oscillator by using the 16MHz to clock a binary counter. At the bottom left of Page 2, we also see three inverters used to invert A7, A4 and A3. This appears to be part of the "address decoding" scheme. Lastly, we see the decoupling capacitors for the inverters and "d-flops". This page (page 2) of the design is fairly solid and well designed. Moving on to page 3, we see the "heart" of the "CC-FlexiMIDI-V1R0-03.09.2009" MIDI Interface Pak. A 74LS133 13-Input NAND is used for address decoding. The 74LS133 in conjunction with the aforementioned inverters and the ACIA enable lines fully decode the ACIA into two consectutive memory addresses. With this, we can now decipher the addressing of the device. This will be done by writing A15 - A0 and filling in the "bit status" required to enable the ACIA, as follows: ========================================================================= | A15 A14 A13 A12 | A11 A10 A09 A08 | A07 A06 A05 A04 | A03 A02 A01 A00 | |=================|=================|=================|=================| | 1 1 1 1 | 1 1 1 1 | 0 1 1 0 | 0 1 1 x | |=================|=================|=================|================== | F | F | 6 | x | ========================================================================= Looking at the above table and noting that A0 selects one of the two internal ACIA registers, it is clear that "Little John" mapped the ACIA to 0xFF66 and 0xFF67. This seems ODD because the most popular MIDI Packs designed for use with the Tandy Radio Shack TRS-80 Color Computer decode the ACIA to 0xFF6E and 0xFF6F. A bit of research, however, led to the discovery that the original CoCo MIDI Pack, "The Colorchestra", mapped the ACIA at 0xFF66 and 0xFF67. The "Colorchestra" was released in 1985 by "Color Horizons" and I own two of them. The aforementioned "research" was simply me looking at the "Colorchestra" P.C.B. and deciphering the address decoding which turns out to be 0xFF66-67. I assume that "Little John" arrived at the 0xFF66-67 addressing in a similar manner as to that just mentioned. It would be relatively easy to redesign the "FlexiMIDI" to respond to both sets of addresses thus guaranteeing compatibility with everything. I have decided, however, that the redesign will feature a semi-programmable address decoder allowing the ACIA to be mapped to any two consecutive addresses within the 0xFF6n area. This will allow the "Flexi-MIDI" to be even more flexible. Setting the address decoder to respond to 0xFF66-67 will make the device "Colorchestra" compatible, whilst setting the decoder to respond to 0xFF6E-6F will make it compatible with the MIDI Interfaces produced by Speech Systems, MusicWare, Rulaford Research, Glenside CoCo Club and other CoCo MIDI Packs. As mentioned, it would be relatively easy to hardwire the decoder to respond to both the 0xFF66-67 and the 0xFF6E-6F address ranges, but I feel that this is unneccesary. Next, we see the 6850 ACIA. This is the "true heart" of the device - a hardware serial port. Looking at the 6850 section of this page of the schematic, we see yet another oddly interesting Interrupt Selection circuit. It is in the form of a 2x4 Jumper Block. This appears to allow selection of any 1 of 4 interrupts to be triggered by the ACIA. IRQ0* and IRQ1* are the previously mentioned "custom" interrupts. NMI* is the 6809 or G.I.M.E./A.C.V.C. Non-Maskable Interrupt Input. The last interrupt on the 2x4 block is the CART* interrupt. This is actually the 6809 or G.I.M.E. IRQ* line that is passed through a PIA inside the CoCo/Dragon. This, the CART* interrupt is the one that should be used for compatibility. The remaining circuitry on Page 3 are fairly standard circuits for MIDI IN, OUT and THROUGH. These go to 5-pin headers. It appears that "Little John" intended for MIDI Cable ends to be soldered to these headers. The redesign will feature 5-pin DIN MIDI connectors. I do see some potential problems with these MIDI IN, OUT and THRU connections on "Little John's" original design. The first problem that I notice is that the MIDI Ground Pins are connected to the same Ground (common or GND) as the computer and MIDI Pack circuitry. This is no good as it violates the MIDI specification and defeats the purpose of the opto-isolator. Thus, the redesign will sever the ground connection of the DIN connectors from the ground connection of the MIDI Interface Pak circuitry. Next, the 330 Ohm (330R) pull-up resistor connected to the output of the opto-isolator should probably be 270R, however, the device should work fine with the 330R resistor. The redesign will have this changed to 270R. The 10K resistor connected to the "BASE" of the opto-isolator darlington-transistor pair should not be needed. I will allow for it in the redesign for testing purposes. The output of the opto-isolator is sent through two schmitt trigger inverters before being applied to the "Receive Data" input of the ACIA. I am drawing the following conclusion in regards to those two inverters: It seems the design was originally intended for use with a Sharp PC-900 or PC-900V digital opto-isolator which has an internal schmitt trigger, the hysteresis of which provides nice, sharp waveform edges. It appears that "Little John" decided, instead, to use a 6N138 opto-isolator, which does not have hysteresis (schmitt triggering) and thus he must have included the two inverters to alleviate this perceived problem. I am relatively certain, however, that these two inverters are unneccessary and thus I will remove them in the redesign. Had I not used two of the inverters in the hex-inverter package for address decoding, I might have left these two inverters in the redesign, however, I decided the savings of one chip was worth eliminating these two inverters. Hopefully, results will be satisfactory. That is about it for the initial analysis of "Little John's" original design. I shall now proceed to design a slightly improved and, hopefully, manufacturable version of "Little John's CC-FlexiMIDI-V1R0-03.09.2009" Hardware M.I.D.I. Interface Pack. This redesign will be titled: "CC-FlexiMIDI-V1R1-03.09.2009". ================================ THE REDESIGN: Load up the NEW design from the CURRENT folder in the archive and use it to follow this discussion. Starting with Page 1 of the schematic, I will start the redesign with the Cartridge Program Pak Slot Plug (Edge-Card or Edge-Fingers). This is what will actually plug into the cartridge port on the computer or Multi-Pak Interface (M.P.I.). Next, I will add an edge card socket wired in parallel to the edge-fingers. This is based on "Little John's" Universal Footprint which means that you can fit either a 40-pin card socket or a 40-pin header. This will allow an additional cartridge or other hardware to be plugged directly into the MIDI Interface, thus eliminating the need for a "y-cable" or Multi-Pak Interface. The +5V is filtered with a 220uF Electrolytic Capacitor in parallel with a .1uF Ceramic Disc or Dacron/Polyester/Mylar capacitor. A Power ON L.E.D. indicator is included here, along with an enable/disable jumper. Removing the jumper disables the Power ON L.E.D. should it become a distraction. Next, I'll add in the "CUSTOM" Interrupts, including their jumpers. The jumpers should be REMOVED from all of these if the device is to be used with a CoCo 1 and/or M.P.I. (Multi-Pak Interface) or with ANY of the CoCo Clones and/or compatibles, including the Dragon. In actuality, these jumpers should never be needed and thus should never be installed - they are for experimental purposes only. Removing the jumpers prevents the accidental application of +/-12V to the IRQ* output pin of the ACIA which would fry the ACIA. I have included 680R "failsafe" resistors, but it is likely that they would not prevent a fried ACIA. Lastly, I have included the RESET Switch for convenience. The RESET switch should NEVER be pressed if the device is inserted in a Multi-Pak Interface as you may blow the 74LS367 in the M.P.I. That is about it for Page 1 of the redesign. Moving on to Page 2: This page is exclusively dedicated to the Baud Rate Generator for the ACIA. Starting at the left, we see the bypass capacitors for the 74LS590 counter. I have used both a 10uF Electrolytic and a .1uF (100nF) Ceramic Disc. This would be important for a ripple counter, however, the LS590 is a synchronous counter and so the Electrolytic could be omitted. I chose to leave it in. There is also a bypass capacitor for the 16MHz oscillator can. I created a dual-footprint for the oscillator can which allows the use of a full or half can oscillator. The 16MHz is fed into the LS590 counter which provides a choice of ten different clocks for the ACIA. For compatibility with existing standard MIDI packs for the CoCo, the 500KHz clock should be selected. The LS590 has an output register which is clocked by the same 16MHz that clocks the counter section. The enable pin of the oscillator is connected to system RESET* which prevents it from oscillating when the system is in a reset state. This pin could have been left floating causing the oscillator to always oscillate. It will work either way. Page 3 is the semi-programmable address decoder. The 74LS133 in conjunction with the two inverters decodes 0xFF6n - the output will go low on any access to the 0xFF6x range. Only 12 of the 13 inputs to the LS133 were needed. The unused input could be connected to Vcc, E or RESET*. It is important to gate the E Clock in at some point and it could have been done here. I chose to connect the input to RESET*. The ACIA actually has an E Clock input which gates it with the E-Clock so it probably does not need to be gated to the address decoder, though, as you'll see, I gated the E-Clock into the next stage. The 74LS138 decodes 1 of 8 sets of even/odd addresses in the 0xFF6n range (it is enabled by the output of the LS133 and the E-Clock).) So, when any address in the 0xFF6n range appears on the address buss during the high time of the E-clock, the LS138 is enabled and decodes A1-A3 into 1-of-8 chip selects. For maximum compatibility, the 0xFF6E-F output should be selected. Page 4: This is the 6850 ACIA. This should be either a 68B50 or a 63B50 or 63C50 for operation at up to 2MHz CPU Clocks. This should be pretty self-explanatory. The 6850 datasheet can fill in any necessary details. Page 5: This is a fairly standard MIDI IN circuit. There are two optocouplers here: a 6N138 and a PC-900 - You should use ONLY ONE, not both. R9 is only needed if you use the 6N138. The diode is a 1N4148 or 1N914A. Page 6: This is a fairly standard MIDI Out circuit. Page 7: This is the final page and is a fairly standard MIDI Thru circuit. It simply echoes the MIDI In. Well, that's about it for a redesign of "Little John's" original. I am ordering some prototype boards to see if this thing will work. Updated to CC-FlexiMIDI-V1R2-12.29.2019 on December 29, 2019 - This minor update: A Universal 5-Pin DIN component was created and the GND Connection was reconnected to MIDI OUT and MIDI THRU. NO GND connection was made to MIDI IN. This should now create a proper MIDI Interface.
The-Little-Engineers-Replacement-Designs-For-The-TM20K370-and-TM21K460-Motorized-Wheels
The Little Engineers Replacement Designs For The TM20K370 and TM21K460 Motorized Wheels http://www.TheLittleEngineers.org/ We are in search of machine shop(s) that might be willing to provide prototype level machining services in exchange for being listed as a recommended manufacturer and/or supplier in all of the open source projects created by The Little Engineers. Contact may be made via: https://www.facebook.com/OurLittleEngineers/ and/or https://www.facebook.com/groups/985537051651794/ All of the projects from The Little Engineers may be found here: https://github.com/TheLittleEngineers?tab=repositories We intend, eventually, to acquire some small scale 3D Printers and CNC mills/routers to aid in our efforts, however we are currently unable to do so mainly due to finances - We try to operate The Little Engineers as much "out of pocket" as we possibly can. Supporting the Foster Care system is that important to us. ==================== In my quest to build Tod Loofbourrows "Microtron" Robot, it became necessary to design a suitable replacement for the long discontinued motorized wheels that Tod made use of - The Herbach and Rademan, Inc. Catalog #TM20K370 Motorized Wheel. That original version was later replaced by Catalog #TM21K460 which was more or less a direct replacement and then almost a decade later by a much cheaper version of which I do not currently have a catalog number. The much cheaper version can be seen in "BUILD A REMOTE-CONTROLLED ROBOT FOR UNDER $300" by David R. Shircliff, now being published as "BUILD A REMOTE CONTROLLED ROBOT" by David R. Shircliff. That book, in its currently published form, does a terrible disservice to its readers by continuing to cite Herbach and Rademan as the source for those motorized wheels which have not been available for decades - it needs to be seriously updated to recommend some other type of motorized wheel rather than continuing to recommend a motorized caster wheel that has been unavailable for decades. Tods original MicroTron "Mike" article may be found here: https://archive.org/details/197704InterfaceAge with further information available here: http://microtron.nu/, here: http://cyberneticzoo.com/wp-content/uploads/2010/09/Mike-Microtron-InterfaceAge-Apr1977.pdf and here: http://microtron.nu/introducing-microtron/ with complete construction details available in the book "HOW TO BUILD A COMPUTER-CONTROLLED ROBOT" by Tod Loofbourrow. It might also be pertinent to review "BUILD YOUR OWN WORKING ROBOT" by David L. Heiserman as Tod utilized the Drive and Steering circuits from Davids book to interface MicroTrons computer to the motorized wheels.
TS2068-CARTRIDGE-2012
TS2068-CARTRIDGE-2012 is intended to be a Timex Sinclair 2068 (TS-2068 or TS2068) TCC (Timex Command Cartridge). It accepts a 27C512 EPROM.
TheLittleEngineers's Repositories
TheLittleEngineers/CoCoDragon-MultiPakInterface-CC-Multi-Pak_Version_1.2
CoCoDragon-MultiPakInterface-CC-Multi-Pak_Version_1.2 - This is a clone of the Tandy Radio Shack TRS-80 Color Computer Multi-Pak Interface #26-3024 (which should also be compatible with the #26-3124). This was designed by my nephew "Little John" and his father "Big John" (J.R. as he is known to me). I have made very minor modifications to it. "Little John" designed this thing to work with ATX Power Supplies, which makes sense I guess - that is the most common power supply in the whole of the known universe. Please note that I have not yet tested this but I am ordering boards and will post an update after initial testing has been completed.
TheLittleEngineers/CoCoDragonFlexiMIDI-V1R2
CC-FlexiMIDI-V1R0-03.09.2009 and CC-FlexiMIDI-V1R1-03.09.2009 : Updated to CC-FlexiMIDI-V1R2-12.29.2019 on December 29, 2019 ================================ BACKGROUND: CC-FlexiMIDI-V1R0-03.09.2009 - A Hardware M.I.D.I. Interface Program Pak Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2 and 3, including clones and compatibles (Tano Dragon 64, Dragon Data D32, D64 and D200, Tandy Data Products TDP-100, etcetera) by "Little" John Eric Turner and his father "Big" John Robert (J.R.) Turner. Copyright 09 March 2009. Originally released as Open-Source Hardware on March 9, 2009. Subsequently released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License on 21 May 2019. ENJOY! Note that the original design is crap, however, a debugged version is forthcoming from "Uncle" Robert "The R.A.T." Allen Turner. CC-FlexiMIDI-V1R0-03.09.2009 has been updated to CC-FlexiMIDI-V1R1-03.09.2009 by R.A. Turner on May 21, 2019, just over ten years after the initial release of Version 1, Revision 0. Version 1, Revision 1 is Copyright (C) 2019 by the above mentioned parties and is released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License on 21 May 2019. =============================== DESCRIPTION: This project is an updated version of the "CC-FlexiMIDI-V1R0-03.09.2009", a hardware MIDI Interface Card for the Tandy Radio Shack TRS-80 Color Computer 1,2 and 3, Dragon Data Dragon D32, D64 and D200, Tandy Data Products TDP-100, Tano Dragon 64 and other clones and compatibles. The original "CC-FlexiMIDI-V1R0-03.09.2009" was designed by my nephew, "Little John", on March 8-9, 2009 as a learning excercise. He was teaching himself to use E.A.G.L.E. in order to design products for the TRS-80 Color Computer line of computers, with the help of his father, my brother, "Big John" or "J.R." as he is known to me. The "CC-FlexiMIDI-V1R0-03.09.2009" was among his very first (learning the art of circuit design) works. It is a terrible design only because he knew nothing about circuit design at the time and it does not appear that his father, "Big John" (J.R.) offered any input in regards to this particular design. I, "Uncle" Robert "The R.A.T." Allen Turner, have decided to polish up the design a bit and lay out a manufacturable Printed Circuit Board which I will release under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License. As such, I will analyze "Little John's" original design and then provide my improved version. The original "CC-FlexiMIDI-V1R0-03.09.2009" design files, as provided by "Little John" and his father (J.R.) are contained in the "Original (Deprecated)" folder of this archive and should be referenced for this initial analysis of the design. ================================ ANALYSIS OF ORIGINAL DESIGN: Load up the "CC-FlexiMIDI-V1R0-03.09.2009.sch" schematic file and have it handy for this discussion. Starting with Page 1 of the schematic, we see the expected cartridge (program pak) plug followed by an oddly interesting series of "purported" interrupts, labeled IRQ0* and IRQ1* (the "*" indicates low-level triggering, or active low). These "Interrupts", IRQ0* and IRQ1* appear to go, through disable jumpers, to Pins 1 and 2 of the CoCo Cartridge (Program PAK) Connector. This is both ODD and INTERESTING because Pins 1 and 2 of that connector are -12V and +12V, respectively, on ALL CoCo 1's, TDP-100's and ALL Multi-Pak Interfaces. Both of these pins are +12V on the Dragon computers. Those self-same pins, however, are NOT connected to anything on ANY stock, unmodified, CoCo 2 or 3 computers. I am thus forced to draw the following conclusion: "Little John" apparently allowed for using Pins 1 and 2 of a CoCo 2 or 3 Cartridge Slot to connect to any desired interrupt within the CoCo 2 or 3. That is, a CoCo 2 or 3 might be modified to connect Pins 1 and/or 2 of the Cartridge Slot to any of the CPU Interrupts, the PIA Interrupt (CART*), G.I.M.E. (A.C.V.C.) Interrupts (CoCo 3 only), etcetera. This is an UNECCESSARY feature of the "FlexiMIDI" design and my initial inclination was to omit it from the design. However, since there are jumpers that allow these "hacked in" custom interrupts to be disabled (removed) via JP1 and/or JP2 or connected together (wire or'ed) via JP3, I have decided to leave them in the design should anyone be so inclined as to use this custom interrupt scheme for experimentation or otherwise. Also on Page 1 is a fairly standard RESET switch which I would imagine could prove to be quite convenient but potentially problematic if the device is plugged into a Multi-Pak Interface (RESET* is buffered in a single direction in the M.P.I. and should not be triggered from any cartridge plugged into the M.P.I.), Power ON L.E.D. (which I assume might be quite distracting) and some pull-up resistors for the interrupts, custom and legit. Lastly, there is a 220uF Electrolytic Capacitor for Vcc (+5V) filtering. Ideally, a low ESR Electrolytic should be used, however, paralleling a 220uF Electrolytic with a .1uF Ceramic Disc should provide approximately the same result as a single Low ESR type. Moving on to Page 2, we see a crystal oscillator comprised of three inverters, three resistors and a crystal rated at 1 to 2 MHz. The third inverter actually acts as a buffer and "shaper". Schmitt Trigger inverters are used, although this is not actually necessary it does provide a nice, sharp square wave. Without the hysteresis provided by the schmitt triggers the waveform would appear quasi-sinusoidal at the crystal frequency if viewed on an oscilloscope, but would still function just fine. The output of that third inverter, the buffer stage, is fed into a pair of toggling D type Flip-Flops which provide a divide by two output and a divide by four output, either of which may be selected by jumper JP4. Ideally, we want a solid 500KHz squarewave as the ACIA Clock (which "Little John" labeled "MIDICLOCK" or "MIDICLK"). If a 1MHz crystal is used we would place JP4 on Pins 1 and 2. With a 2MHz crystal we would connect JP4 Pins 2 and 3. This is flexible in that it allows the use of either a 1MHz or 2MHz crystal, whichever might be handy. In my case, and for the redesign, I have a large stock of 16MHz half-can oscillators and so this is what I will be using in the redesign. The 500KHz then, will be derived from the 16MHz oscillator by using the 16MHz to clock a binary counter. At the bottom left of Page 2, we also see three inverters used to invert A7, A4 and A3. This appears to be part of the "address decoding" scheme. Lastly, we see the decoupling capacitors for the inverters and "d-flops". This page (page 2) of the design is fairly solid and well designed. Moving on to page 3, we see the "heart" of the "CC-FlexiMIDI-V1R0-03.09.2009" MIDI Interface Pak. A 74LS133 13-Input NAND is used for address decoding. The 74LS133 in conjunction with the aforementioned inverters and the ACIA enable lines fully decode the ACIA into two consectutive memory addresses. With this, we can now decipher the addressing of the device. This will be done by writing A15 - A0 and filling in the "bit status" required to enable the ACIA, as follows: ========================================================================= | A15 A14 A13 A12 | A11 A10 A09 A08 | A07 A06 A05 A04 | A03 A02 A01 A00 | |=================|=================|=================|=================| | 1 1 1 1 | 1 1 1 1 | 0 1 1 0 | 0 1 1 x | |=================|=================|=================|================== | F | F | 6 | x | ========================================================================= Looking at the above table and noting that A0 selects one of the two internal ACIA registers, it is clear that "Little John" mapped the ACIA to 0xFF66 and 0xFF67. This seems ODD because the most popular MIDI Packs designed for use with the Tandy Radio Shack TRS-80 Color Computer decode the ACIA to 0xFF6E and 0xFF6F. A bit of research, however, led to the discovery that the original CoCo MIDI Pack, "The Colorchestra", mapped the ACIA at 0xFF66 and 0xFF67. The "Colorchestra" was released in 1985 by "Color Horizons" and I own two of them. The aforementioned "research" was simply me looking at the "Colorchestra" P.C.B. and deciphering the address decoding which turns out to be 0xFF66-67. I assume that "Little John" arrived at the 0xFF66-67 addressing in a similar manner as to that just mentioned. It would be relatively easy to redesign the "FlexiMIDI" to respond to both sets of addresses thus guaranteeing compatibility with everything. I have decided, however, that the redesign will feature a semi-programmable address decoder allowing the ACIA to be mapped to any two consecutive addresses within the 0xFF6n area. This will allow the "Flexi-MIDI" to be even more flexible. Setting the address decoder to respond to 0xFF66-67 will make the device "Colorchestra" compatible, whilst setting the decoder to respond to 0xFF6E-6F will make it compatible with the MIDI Interfaces produced by Speech Systems, MusicWare, Rulaford Research, Glenside CoCo Club and other CoCo MIDI Packs. As mentioned, it would be relatively easy to hardwire the decoder to respond to both the 0xFF66-67 and the 0xFF6E-6F address ranges, but I feel that this is unneccesary. Next, we see the 6850 ACIA. This is the "true heart" of the device - a hardware serial port. Looking at the 6850 section of this page of the schematic, we see yet another oddly interesting Interrupt Selection circuit. It is in the form of a 2x4 Jumper Block. This appears to allow selection of any 1 of 4 interrupts to be triggered by the ACIA. IRQ0* and IRQ1* are the previously mentioned "custom" interrupts. NMI* is the 6809 or G.I.M.E./A.C.V.C. Non-Maskable Interrupt Input. The last interrupt on the 2x4 block is the CART* interrupt. This is actually the 6809 or G.I.M.E. IRQ* line that is passed through a PIA inside the CoCo/Dragon. This, the CART* interrupt is the one that should be used for compatibility. The remaining circuitry on Page 3 are fairly standard circuits for MIDI IN, OUT and THROUGH. These go to 5-pin headers. It appears that "Little John" intended for MIDI Cable ends to be soldered to these headers. The redesign will feature 5-pin DIN MIDI connectors. I do see some potential problems with these MIDI IN, OUT and THRU connections on "Little John's" original design. The first problem that I notice is that the MIDI Ground Pins are connected to the same Ground (common or GND) as the computer and MIDI Pack circuitry. This is no good as it violates the MIDI specification and defeats the purpose of the opto-isolator. Thus, the redesign will sever the ground connection of the DIN connectors from the ground connection of the MIDI Interface Pak circuitry. Next, the 330 Ohm (330R) pull-up resistor connected to the output of the opto-isolator should probably be 270R, however, the device should work fine with the 330R resistor. The redesign will have this changed to 270R. The 10K resistor connected to the "BASE" of the opto-isolator darlington-transistor pair should not be needed. I will allow for it in the redesign for testing purposes. The output of the opto-isolator is sent through two schmitt trigger inverters before being applied to the "Receive Data" input of the ACIA. I am drawing the following conclusion in regards to those two inverters: It seems the design was originally intended for use with a Sharp PC-900 or PC-900V digital opto-isolator which has an internal schmitt trigger, the hysteresis of which provides nice, sharp waveform edges. It appears that "Little John" decided, instead, to use a 6N138 opto-isolator, which does not have hysteresis (schmitt triggering) and thus he must have included the two inverters to alleviate this perceived problem. I am relatively certain, however, that these two inverters are unneccessary and thus I will remove them in the redesign. Had I not used two of the inverters in the hex-inverter package for address decoding, I might have left these two inverters in the redesign, however, I decided the savings of one chip was worth eliminating these two inverters. Hopefully, results will be satisfactory. That is about it for the initial analysis of "Little John's" original design. I shall now proceed to design a slightly improved and, hopefully, manufacturable version of "Little John's CC-FlexiMIDI-V1R0-03.09.2009" Hardware M.I.D.I. Interface Pack. This redesign will be titled: "CC-FlexiMIDI-V1R1-03.09.2009". ================================ THE REDESIGN: Load up the NEW design from the CURRENT folder in the archive and use it to follow this discussion. Starting with Page 1 of the schematic, I will start the redesign with the Cartridge Program Pak Slot Plug (Edge-Card or Edge-Fingers). This is what will actually plug into the cartridge port on the computer or Multi-Pak Interface (M.P.I.). Next, I will add an edge card socket wired in parallel to the edge-fingers. This is based on "Little John's" Universal Footprint which means that you can fit either a 40-pin card socket or a 40-pin header. This will allow an additional cartridge or other hardware to be plugged directly into the MIDI Interface, thus eliminating the need for a "y-cable" or Multi-Pak Interface. The +5V is filtered with a 220uF Electrolytic Capacitor in parallel with a .1uF Ceramic Disc or Dacron/Polyester/Mylar capacitor. A Power ON L.E.D. indicator is included here, along with an enable/disable jumper. Removing the jumper disables the Power ON L.E.D. should it become a distraction. Next, I'll add in the "CUSTOM" Interrupts, including their jumpers. The jumpers should be REMOVED from all of these if the device is to be used with a CoCo 1 and/or M.P.I. (Multi-Pak Interface) or with ANY of the CoCo Clones and/or compatibles, including the Dragon. In actuality, these jumpers should never be needed and thus should never be installed - they are for experimental purposes only. Removing the jumpers prevents the accidental application of +/-12V to the IRQ* output pin of the ACIA which would fry the ACIA. I have included 680R "failsafe" resistors, but it is likely that they would not prevent a fried ACIA. Lastly, I have included the RESET Switch for convenience. The RESET switch should NEVER be pressed if the device is inserted in a Multi-Pak Interface as you may blow the 74LS367 in the M.P.I. That is about it for Page 1 of the redesign. Moving on to Page 2: This page is exclusively dedicated to the Baud Rate Generator for the ACIA. Starting at the left, we see the bypass capacitors for the 74LS590 counter. I have used both a 10uF Electrolytic and a .1uF (100nF) Ceramic Disc. This would be important for a ripple counter, however, the LS590 is a synchronous counter and so the Electrolytic could be omitted. I chose to leave it in. There is also a bypass capacitor for the 16MHz oscillator can. I created a dual-footprint for the oscillator can which allows the use of a full or half can oscillator. The 16MHz is fed into the LS590 counter which provides a choice of ten different clocks for the ACIA. For compatibility with existing standard MIDI packs for the CoCo, the 500KHz clock should be selected. The LS590 has an output register which is clocked by the same 16MHz that clocks the counter section. The enable pin of the oscillator is connected to system RESET* which prevents it from oscillating when the system is in a reset state. This pin could have been left floating causing the oscillator to always oscillate. It will work either way. Page 3 is the semi-programmable address decoder. The 74LS133 in conjunction with the two inverters decodes 0xFF6n - the output will go low on any access to the 0xFF6x range. Only 12 of the 13 inputs to the LS133 were needed. The unused input could be connected to Vcc, E or RESET*. It is important to gate the E Clock in at some point and it could have been done here. I chose to connect the input to RESET*. The ACIA actually has an E Clock input which gates it with the E-Clock so it probably does not need to be gated to the address decoder, though, as you'll see, I gated the E-Clock into the next stage. The 74LS138 decodes 1 of 8 sets of even/odd addresses in the 0xFF6n range (it is enabled by the output of the LS133 and the E-Clock).) So, when any address in the 0xFF6n range appears on the address buss during the high time of the E-clock, the LS138 is enabled and decodes A1-A3 into 1-of-8 chip selects. For maximum compatibility, the 0xFF6E-F output should be selected. Page 4: This is the 6850 ACIA. This should be either a 68B50 or a 63B50 or 63C50 for operation at up to 2MHz CPU Clocks. This should be pretty self-explanatory. The 6850 datasheet can fill in any necessary details. Page 5: This is a fairly standard MIDI IN circuit. There are two optocouplers here: a 6N138 and a PC-900 - You should use ONLY ONE, not both. R9 is only needed if you use the 6N138. The diode is a 1N4148 or 1N914A. Page 6: This is a fairly standard MIDI Out circuit. Page 7: This is the final page and is a fairly standard MIDI Thru circuit. It simply echoes the MIDI In. Well, that's about it for a redesign of "Little John's" original. I am ordering some prototype boards to see if this thing will work. Updated to CC-FlexiMIDI-V1R2-12.29.2019 on December 29, 2019 - This minor update: A Universal 5-Pin DIN component was created and the GND Connection was reconnected to MIDI OUT and MIDI THRU. NO GND connection was made to MIDI IN. This should now create a proper MIDI Interface.
TheLittleEngineers/27C512E-TO-2532S-V1R1.20.APRIL.2019
TheLittleEngineers.org-27C512E-TO-2532S-V1R1.20.APRIL.2019 27C512 E.P.R.O.M. TO TMS2532 SOCKET CONVERTER. (C) 20 April 2019 and 01 June 2019 by: Robert Allen Turner http://www.TheLittleEngineers.org/ https://github.com/TheLittleEngineers This product is intended to allow a 27512 or 27C512 EPROM to be placed into a TMS2532 EPROM socket. The 27512 is divided into 16 banks of 4Kbytes via the four jumpers at the bottom of the socket. Released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License, 01 June 2019 In Memory of my Father, Robert Embry Turner, 1945 - 2019. Rest In Peace. I LOVE YOU DAD! Archive name: "TheLittleEngineers.org-27C512E-TO-2532S-V1R1.20.APRIL.2019" This is an update to the "TheLittleEngineers.org-27C512E-TO-2532S-V1R0.20.APRIL.2019" repository which resides at this url: https://github.com/TheLittleEngineers/27C512E-TO-2532S-V1R0 This update was made due to the fact that I was not very pleased with the initial Printed Circuit Boards that resulted from the original design. Although functional, the production of the Printed Circuit Boards was inconsistent between different manufacturers. This was due to a problem in the dimension layer of the original design and so I have created this new design to eliminate the inconsistencies. This version should provide much better results.
TheLittleEngineers/CC2-32K-EPROM-CARTRIDGE-2012-V2R0
This is an EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1,2 and 3. It will probably work with the Dragon Data Dragon computers as well. It uses a 27C512 EPROM jumper selected as two 32K banks. The CoCo 1, 2 and Dragon can only access the first 16K of each bank. The CoCo 3 can access the entire 32K of each bank, minus the 0xFFnn I/O and Vector page. The project has been shared to github: https://github.com/TheLittleEngineers/CC2-32K-EPROM-CARTRIDGE-2012-V2R0. Many other similar cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. The project is released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License [https://creativecommons.org/licenses/by-sa/4.0/] github: https://github.com/TheLittleEngineers/CC2-32K-EPROM-CARTRIDGE-2012-V2R0 OSHpark: https://oshpark.com/shared_projects/wl9Kmtit Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
TheLittleEngineers/CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1
CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1 is the 32K Version of the CoCoDragon-8K-EPROM-Cartridge-CC1-8KEC-0001.1 - It is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. This was one of the very first things that my nephew created when he was teaching himself electronics and computer design - it works, but could be better. He made and sold about 30 or so of these almost ten years ago. The design was meant to be as small as possible so as to fit entirely inside the cartridge Program Pak port and was useful for DriveWire or CoCoNet. It uses a 27256 EPROM. Updated to version 0001.1 on 5 May 2019 by “Ankle” Bob and released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License [https://creativecommons.org/licenses/by-sa/4.0/] - there is definitely a lot of room for improvement and “Little John” made many improved versions which will be shared as I get more time to do so. There is a github page for this project here: https://github.com/TheLittleEngineers/CoCoDragon-32K-EPROM-Cartridge-CC1-32KEC-0001.1 and an OSHpark page here: https://oshpark.com/shared_projects/mqju7EpZ Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
TheLittleEngineers/CoCoDragon-CC2-32K-EPROM-CARTRIDGE-2012-V1RA
CC2-32K-EPROM-CARTRIDGE-2012-Version-1-Revision-A-07.02.2012 is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order.
TheLittleEngineers/CoCoDragon-CC2-32KEC-V1RA
CC2-32K-EPROM-CARTRIDGE-Version-1-Revision-A-01.06.2013 is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. There is a GitHub Page here:
TheLittleEngineers/The-Little-Engineers-Replacement-Designs-For-The-TM20K370-and-TM21K460-Motorized-Wheels
The Little Engineers Replacement Designs For The TM20K370 and TM21K460 Motorized Wheels http://www.TheLittleEngineers.org/ We are in search of machine shop(s) that might be willing to provide prototype level machining services in exchange for being listed as a recommended manufacturer and/or supplier in all of the open source projects created by The Little Engineers. Contact may be made via: https://www.facebook.com/OurLittleEngineers/ and/or https://www.facebook.com/groups/985537051651794/ All of the projects from The Little Engineers may be found here: https://github.com/TheLittleEngineers?tab=repositories We intend, eventually, to acquire some small scale 3D Printers and CNC mills/routers to aid in our efforts, however we are currently unable to do so mainly due to finances - We try to operate The Little Engineers as much "out of pocket" as we possibly can. Supporting the Foster Care system is that important to us. ==================== In my quest to build Tod Loofbourrows "Microtron" Robot, it became necessary to design a suitable replacement for the long discontinued motorized wheels that Tod made use of - The Herbach and Rademan, Inc. Catalog #TM20K370 Motorized Wheel. That original version was later replaced by Catalog #TM21K460 which was more or less a direct replacement and then almost a decade later by a much cheaper version of which I do not currently have a catalog number. The much cheaper version can be seen in "BUILD A REMOTE-CONTROLLED ROBOT FOR UNDER $300" by David R. Shircliff, now being published as "BUILD A REMOTE CONTROLLED ROBOT" by David R. Shircliff. That book, in its currently published form, does a terrible disservice to its readers by continuing to cite Herbach and Rademan as the source for those motorized wheels which have not been available for decades - it needs to be seriously updated to recommend some other type of motorized wheel rather than continuing to recommend a motorized caster wheel that has been unavailable for decades. Tods original MicroTron "Mike" article may be found here: https://archive.org/details/197704InterfaceAge with further information available here: http://microtron.nu/, here: http://cyberneticzoo.com/wp-content/uploads/2010/09/Mike-Microtron-InterfaceAge-Apr1977.pdf and here: http://microtron.nu/introducing-microtron/ with complete construction details available in the book "HOW TO BUILD A COMPUTER-CONTROLLED ROBOT" by Tod Loofbourrow. It might also be pertinent to review "BUILD YOUR OWN WORKING ROBOT" by David L. Heiserman as Tod utilized the Drive and Steering circuits from Davids book to interface MicroTrons computer to the motorized wheels.
TheLittleEngineers/TS2068-CARTRIDGE-2012
TS2068-CARTRIDGE-2012 is intended to be a Timex Sinclair 2068 (TS-2068 or TS2068) TCC (Timex Command Cartridge). It accepts a 27C512 EPROM.
TheLittleEngineers/2732-to-2532
2732 to 2532 EPROM adapter
TheLittleEngineers/27C512E-TO-2532S-V1R0
(Deprecated - See README.md for link to new version) - This product, TheLittleEngineers.org-27C512E-TO-2532S-V1R0.20.APRIL.2019, is intended to allow a 27512 or 27C512 EPROM to be placed into a TMS2532 EPROM socket. The 27512 is divided into 16 banks of 4Kbytes via the four jumpers at the bottom of the socket. https://github.com/TheLittleEngineers/27C512E-TO-2532S-V1R0 This project is licensed under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License: https://creativecommons.org/licenses/by-sa/4.0/ OshPark: https://oshpark.com/shared_projects/5EPozkYK Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
TheLittleEngineers/CoCoDragon-8K-EPROM-Cartridge-CC1-8KEC-0001.1
This is an 8K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. This was one of the very first things that my nephew created when he was teaching himself electronics and computer design - it works, but could be better. He made and sold about 30 of these almost ten years ago. The design was meant to be as small as possible so as to fit entirely inside the cartridge Program Pak port and was useful for DriveWire or CoCoNet. It uses a 2764 EPROM. Updated to version 0001.1 on 5 May 2019 by "Ankle" Bob and released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License [https://creativecommons.org/licenses/by-sa/4.0/] - there is definitely a lot of room for improvement and "Little John" made many improved versions which will be shared as I get more time to do so. There is an OSHPark page for this project here: https://oshpark.com/shared_projects/CLGrsHfm Please note: This is derived from an original design by "Little" John Eric and/or his father "Big" John Robert (J.R.) by "Uncle" Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided "as-is" with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can't afford not to disclaim the use of this information.
TheLittleEngineers/CoCoDragonFlexiMIDI-V1R1
This project is an updated version of the "CC-FlexiMIDI-V1R0-03.09.2009", a hardware MIDI Interface Card for the Tandy Radio Shack TRS-80 Color Computer 1,2 and 3, Dragon Data Dragon D32, D64 and D200, Tandy Data Products TDP-100, Tano Dragon 64 and other clones and compatibles. The original "CC-FlexiMIDI-V1R0-03.09.2009" was designed by my nephew, "Little John", on March 8-9, 2009 as a learning excercise. He was teaching himself to use E.A.G.L.E. in order to design products for the TRS-80 Color Computer line of computers, with the help of his father, my brother, "Big John" or "J.R." as he is known to me. The "CC-FlexiMIDI-V1R1-03.09.2009" was among his very first (learning the art of circuit design) works. It is a terrible design only because he knew nothing about circuit design at the time and it does not appear that his father, "Big John" (J.R.) offered any input in regards to this particular design.
TheLittleEngineers/eBookTemplate
(Deprecated - As It Turns Out - It Is Easier To Create A Kindle Publication WITHOUT A Template)This is a set of eBook Templates intended to ease the construction of Kindle, PDF and Generic eBooks. They are intended to be ALL INCLUSIVE, containing all possible sections of a book and their descriptions, allowing them to be removed or added, at will and as needed. We will also offer the service of helping to prepare your book for publication if you should require such a service.
TheLittleEngineers/Generic-eBook-and-paperback-self-publishing-template-suitable-for-Kindle-publishing
This repository will contain a universal eBook template that is suitable for use in creating book(s) to be published via Amazon Kindle Direct Publishing. This "generic" template is also quite useful in creating books intended for actual physical publishing/printing. The template is also quite useful in creating "*.pdf" eBooks and documents. This project is intended to be "the only thing you need to get your book formatted for publishin".
TheLittleEngineers/Replacement-Designs-For-The-TM20K370-and-TM21K460-Motorized-Wheels
The Little Engineers Replacement Designs For The TM20K370 and TM21K460 Motorized Wheels The Little Engineers Replacement Designs For The TM20K370 and TM21K460 Motorized Wheels http://www.TheLittleEngineers.org/ We are in search of machine shop(s) that might be willing to provide prototype level machining services in exchange for being listed as a recommended manufacturer and/or supplier in all of the open source projects created by The Little Engineers. Contact may be made via: https://www.facebook.com/OurLittleEngineers/ and/or https://www.facebook.com/groups/985537051651794/ All of the projects from The Little Engineers may be found here: https://github.com/TheLittleEngineers?tab=repositories <i>We intend, eventually, to acquire some small scale 3D Printers and CNC mills/routers to aid in our efforts, however we are currently unable to do so mainly due to finances - We try to operate The Little Engineers as much "out of pocket" as we possibly can. Supporting the Foster Care system is that important to us.</i> In my quest to build Tod Loofbourrows "Microtron" Robot, it became necessary to design a suitable replacement for the long discontinued motorized wheels that Tod made use of - The Herbach and Rademan, Inc. Catalog #TM20K370 Motorized Wheel. That original version was later replaced by Catalog #TM21K460 which was more or less a direct replacement and then almost a decade later by a much cheaper version of which I do not currently have a catalog number. The much cheaper version can be seen in "BUILD A REMOTE-CONTROLLED ROBOT FOR UNDER $300" by David R. Shircliff, now being published as "BUILD A REMOTE CONTROLLED ROBOT" by David R. Shircliff. That book, in its currently published form, does a terrible disservice to its readers by continuing to cite Herbach and Rademan as the source for those motorized wheels which have not been available for decades - it needs to be seriously updated to recommend some other type of motorized wheel rather than continuing to recommend a motorized caster wheel that has been unavailable for decades. Tods original MicroTron "Mike" article may be found here: https://archive.org/details/197704InterfaceAge with further information available here: http://microtron.nu/, here: http://cyberneticzoo.com/wp-content/uploads/2010/09/Mike-Microtron-InterfaceAge-Apr1977.pdf and here: http://microtron.nu/introducing-microtron/ with complete construction details available in the book "HOW TO BUILD A COMPUTER-CONTROLLED ROBOT" by Tod Loofbourrow. It might also be pertinent to review "BUILD YOUR OWN WORKING ROBOT" by David L. Heiserman as Tod utilized the Drive and Steering circuits from Davids book to interface MicroTrons computer to the motorized wheels. We are looking for copies of the monthly Herbach and Rademan Catalogs from 1974 through 1987. Any assistance would be greatly appreciated. NOTE: NOTHING HAS BEEN TESTED AS OF YET - PLEASE COMPARE ANYTHING WITH A 1:1 PRINTOUT OR MAKE A 3D PRINT BEFORE HAVING ANYTHING MANUFACTURED.
TheLittleEngineers/TS2068-CARTRIDGE-READER-2012
TS2068-CARTRIDGE-READER-2012 is intended to allow a Timex Sinclair TS2068 (TS-2068) TCC (Timex Command Cartridge) to be plugged into an EPROM Socket allowing the contents to be read (such as by an EPROM Programmer). This first version was developed June 15, 2012 at 4:33 A.M. C.S.T.
TheLittleEngineers/TS2068-CARTRIDGE-READER-2012-Version-2
TS2068-CARTRIDGE-READER-2012-Version-2 is intended to allow a Timex Sinclair TS2068 (TS-2068) TCC (Timex Command Cartridge) to be plugged into an EPROM Socket allowing the contents to be read (such as by an EPROM Programmer). This first version was developed June 15, 2012 at 4:33 A.M. C.S.T. - This version adds some "blinkenlights" (L.E.D.s)
TheLittleEngineers/2732-tofrom-2532
(Deprecated - See below for link to the new version). This product is intended to allow a 2732 EPROM to be placed into a 2532 EPROM socket or a 2532 EPROM to be placed into a 2732 EPROM socket. The original product seems to have been placed on GitHub at this url: https://github.com/ricardoquesada/2732-to-2532. Being somewhat involved in the original creation of the product, I decided not to fork that repository for this new, slightly improved version, but rather chose to create a new repository. The product is now licensed under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License IN MEMORY OF MY FATHER, ROBERT EMBRY TURNER.
TheLittleEngineers/Baby-AT-Motherboard-Tray
Baby-AT Motherboard Tray - 3D Printable and CNC Machinable. Intended to be the basis of something bigger and better. Developed by "The R.A.T." Customizations MAY be available upon request. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) License: https://creativecommons.org/licenses/by-sa/4.0/ The design allows for the insertion of M3 bolts from the bottom allowing M3 nuts to be "stacked" to act as the standoffs. The larger holes are the standard Baby-AT holes and are 0.156" (3.9624mm) in diameter. The smaller holes are not part of the Baby-AT Standard and are 0.0940" (2.3876mm) in diameter. They fit a #6 Self-Tapping Screw but should probably NOT be used as they were included for my own experimental purposes. Finding information proved somewhat difficult with the included "jpeg/png" being the best that I could do. Anyone having a genuine pdf of the standard and emailing it to me would be greatly appreciated. Any information regarding errors also appreciated.
TheLittleEngineers/CC2-64K-EPROM-CARTRIDGE-2012-Version-1-Revision-A-06.28.2012
CC2-64K-EPROM-CARTRIDGE-2012-Version-1-Revision-A-06.28.2012
TheLittleEngineers/CC3-512KSRAM-V1R03
This is a 512K RAM Upgrade for the Tandy Radio Shack TRS-80 Color Computer 3 that features battery backup.
TheLittleEngineers/CC3-MPI-26-3124-Satellite-Board
The “CC3-MPI-26-3124-Satellite-Board-CoCo-3-Upgrade-2009-V1RA” is a clone of the “Part # AXX-7119 Satellite Board for 26-3124” Multi-Pak Interface CoCo 3 upgrade with the additional feature of being switchable between CoCo 1,2 or 3 mode.
TheLittleEngineers/CC3-SpeedBump-V1R1
This product, TheLittleEngineers.org-CC3-SpeedBump-V1R1-30-MARCH-1987, is intended to add the old TRS80 Color Computer 1 and 2 High-Speed POKE back to the Tandy Color Computer 3, in hardware.
TheLittleEngineers/CoCo-Dragon-Multi-Pak-Interface
TheLittleEngineers/CoCo_Dragon_Multipak_CAD_Library
This is intended to be a library of components specifically geared to the creation of buss expansion devices for the CoCo, Dragon, Clones and Compatibles. There are Eagle (BIN and XML) and KiCAD Libraries Currently.
TheLittleEngineers/CoCoDragon-CC2-32KEC-V1RA1
CC2-32K-EPROM-CARTRIDGE-Version-1-Revision-A1-01.06.2013 is a 32K EPROM Cartridge for the Tandy Radio Shack TRS-80 Color Computer 1, 2, 3 and Dragon Data Dragon computers. Notes: The CoCo 1, 2 and Dragon can only access the first 16K. The CoCo 3 can access the entire 32K, minus the 0xFFnn I/O and Vector page. Many other similar (but much improved) cartridges are forthcoming. There are much better designs in my possession and I intend to post them all, in no particular order. There is a GitHub Page here: https://github.com/TheLittleEngineers/CoCoDragon-CC2-32KEC-V1RA1 - PLEASE NOTE: THIS VERSION HAS NOT YET BEEN TESTED. Please note: This is derived from an original design by “Little” John Eric and/or his father “Big” John Robert (J.R.) by “Uncle” Robert Allen. It should be thoroughly scrutinized and verified prior to actual use of any kind. DISCLAIMER: The following article is provided for informational purposes only. Any attempt to modify your computer without the proper skills to do so may void your computer. Any attempt to modify your computer without unplugging it first may void you. This Information is provided “as-is” with no guarantee of fitness for any purpose, either explicit or implied. We disclaim any and all responsibility for losses incurred through the use of this information. By using this information, you are deemed to have accepted these conditions of use, and you agree NOT to sue us. CLARIFICATION: The above disclaimer states as plainly as possible that if you decide to make use of any of the information contained within this document that you do so at your own risk. Designing hardware for the CoCo (ColorComputer) and other vintage hardware is a hobby of ours and is not motivated by any desire of profits. As this is a not for profit venture, obviously we can’t afford not to disclaim the use of this information.
TheLittleEngineers/CoCoDragonBufferPak-V1R0
A simple buffer pack for the CoCo/Dragon/Clones. All signals are buffered except for the 5V and 12V Supplies, SND and SLENB*. Designed by: "The R.A.T." May 21, 2019. LICENSE: CC BY-SA 4.0. I decided that, if I was going to be plugging untested prototypes into my CoCo, I needed to provide at least some protection against frying the poor thing. This is the result of that "protection effort".
TheLittleEngineers/JavaScript_DropDown_URL_Selection
Simple JavaScript for creating a DropDown URL selection box.