/monster-fdc

ISA floppy disk controller card that supports up to 8 floppy drives

Monster Floppy Disk Controller (Monster FDC)

ISA floppy disk controller card that supports up to 8 floppy drives

Introduction

Monster FDC is an ISA floppy disk controller card that features two FDCs. Each FDC supports up to four floppy drives. IRQ and DMA channel are configurable for the secondary FDC, and they are hardwired to IRQ6 and DMA2 for the primary FDC. The card also includes a serial port (UART) with configurable I/O address and IRQ.

Monster FDC Assembled Board

User Manuals

  • Refer to Assembly Instructions for the controller board building instructions
  • Refer to User Manual for configuration, installation, and using the controller board in the computer

Hardware Documentation

Schematic and PCB Layout

Schematic - Version 1.0

PCB Layout - Version 1.0

Bill of Materials

Version 1.0

Monster FDC project on Mouser.com - View and order all components except of the PCB and the FDC ICs. Note that this BOM includes multiple alternatives for some parts (for example, for 2x17 pin floppy disk connector). Make sure to refer to the BOM below to order the right number of components.

Monster FDC project on Tindie: Complete Board; Monster FDC PCB.

Component type Reference Description Quantity Possible sources and notes
PCB Monster PCB - Version 1.0 1 Buy from my Tindie store: Monster FDC PCB, or order from a PCB manufacturer of your choice using provided Gerber or KiCad files. It is recommended to use hard gold plating on the card edge connector. ENIG finish might work, but it is not as reliable. Definitely DO NOT use HASL finish on card edge connector.
Integrated Circuit U1, U2 Intel 82077AA FDC, 68 pin PLCC 2 eBay; Possible replacements: National Semiconductor PC8477BV-1 or PC8477AV-1, Intel 82077SL, Intel 82077AA with various suffixes
Integrated Circuit U3 16C550 UART, 44 pin PLCC 1 Mouser 701-ST16C550CJ44-F
Integrated Circuit U4 GD75232N RS-232 Transceivers, 20 pin DIP 1 Mouser 595-GD75232N
Integrated Circuit U5 SST39SF010A - 128 KiB Flash ROM, 32 pin DIP 1* Mouser 804-39SF010A7CPHE; Possible replacements: 128 KiB, 256 KiB, or 512 KiB 5V only Flash ROMs from other vendors. Note: Install either U5 or U6. It is recommended to install U5
Integrated Circuit U6 28C256 32 KiB or 28C64 8 KiB EEPROM, 28 pin DIP 1* Mouser 556-AT28C25615PU, 556-AT28C64B15PU. Note: Install either U5 or U6. It is recommended to install U5
Integrated Circuit U7 CD74HCT688E Magnitude Comparator, 20 pin DIP 1 Mouser 595-CD74HCT688E
Integrated Circuit U8 - U10 SN74AHCT138N 3-to-8 Decoder, 16 pin DIP 3 Mouser 595-SN74AHCT138N
Crystal Oscillator X1 24 MHz, 4 pin DIP, Half Can 1 Mouser 520-TCH2400
Crystal Oscillator X2 1.8432 MHz, 4 pin DIP, Half Can 1 Mouser 520-TCH184-X
Connector J1 - J4 2x17 pin shrouded header, 2.54 mm pitch, vertical 4 Mouser 517-30334-6002
Connector J5 DE-9 D-Sub connector, male, right angle 1 Mouser 806-K22X-E9P-N-99
Pin Header JP1 - JP3 2x6 pin header, 2.54 mm pitch, vertical 3 Mouser 649-67996-112HLF
Pin Header JP4 1x5 pin header, 2.54 mm pitch, vertical 1 Mouser 649-68000-205HLF
Pin Header JP5 2x7 pin header, 2.54 mm pitch, vertical 1 Mouser 649-67996-114HLF
Pin Header JP6 - JP9 2x2 pin header, 2.54 mm pitch, vertical 2* Mouser 649-67996-104HLF. Note: Do not install unless using PS/2 floppy drives that are powered by pin 3
Capacitor C1, C2 4.7 nF, 50V, MLCC, 5 mm pitch 2* Mouser 810-FG28X7R1H472KNT0. Note: Optional, only required when using Intel 82077AA FDC
Capacitor C3 - C17 100 nF, 50V, MLCC, 5 mm pitch 15 Mouser 810-FG28X7R1H104KNT6
Capacitor C18 - C23 10 uF, 63V, Organic Polymer, 6.3 mm diameter, 2.5 mm pitch 5 Mouser 80-A759EA106M1JAAE60
Resistor Array RN1, RN2 1 kohm, bussed, 6 pin SIP 2 Mouser 652-4606X-1LF-1K
Resistor Array RN3, RN4 10 kohm, bussed, 6 pin SIP 2 Mouser 652-4606X-1LF-10K
IC Socket U1, U2 68 pin PLCC, through hole 2 Mouser 517-8468-11B1-RK-TP
IC Socket U3 44 pin PLCC, through hole 1 Mouser 517-8444-11B1-RK-TP
IC Socket U4, U7 20 pin DIP 2 Mouser 649-DILB20P-223TLF
IC Socket U5 32 pin DIP 1* Mouser 649-DILB32P223TLF. Note: Install either U5 or U6. It is recommended to install U5
IC Socket U6 28 pin DIP 1* Mouser 649-DILB28P223TLF. Note: Install either U5 or U6. It is recommended to install U5
IC Socket U8 - U10 16 pin DIP 1 Mouser 649-DILB16P-223TLF
Oscillator Socket X1, X2 4 pin DIP, Half Can 2 Mouser 535-1108800
Jumper JP1 - JP5 Shunt, 2 pin 2.54 mm pitch 13 Mouser 806-SX1100-B
Computer Bracket Keystone Electronics 9200-1 Bracket with DE-9 cut-out 1 Mouser 534-9200-1, or a 3D printed bracket. Note: Use when serial port components are populated
Screw 4-40 Hex screw for D-Sub Connector 2 Mouser 806-JSX-1000. Note: Use when serial port components are populated
Computer Bracket Keystone Electronics 9202 ISA Bracket 1 Mouser 534-9202. Note: Use when serial port components are not populated
Screw 4-40 / 1/4" screw (for attaching ISA Bracket to the board) 2 Mouser 534-9900. Note: Use when serial port components are not populated

Devices and Functionality

The card can be built with some or all of the following devices and functionality:

  • Primary FDC controller
  • Secondary FDC controller
  • Serial port / UART
  • BIOS extension ROM (aka boot ROM)

The table below provides the list of components that are required for each one of the devices

Device/Functionality Components
Primary FDC Controller U1, U8, U9, X1, J1, J2, JP1, JP6**, JP7**, C1*, C3, C5, C11, C12, C14, C19, RN1, RN4
Secondary FDC Controller U2, U8, U10, X1, J3, J4, JP1, JP2, JP3, JP8**, JP9**, C2*, C4, C6, C11, C13, C14, C20, RN2, RN4
Serial port / UART U3, U4, U8, U9, X2, J5, JP1, JP2, JP4, C7, C8, C11, C12, C15, C16, C17, C22, C23, RN4
BIOS extension ROM U5***, U6***, U7, JP5, RN3, C9, C10
Shared components C18

Notes:

  • * - only required for Intel 82077AA FDCs
  • ** - only required when using IBM PS/2 floppy drives that are powered by 5V on pin 3
  • *** - install either U5 (recommended) or U6
  • Use Keystone Electronics 9200-1 Bracket when populating serial port components. This bracket attaches to the serial port DE-9 connector
  • Use Keystone Electronics 9202 ISA Bracket when not populating serial port components. This bracket attaches to the board with a couple of 4-40 screws

Possible Component Replacements

  • U1, U2 - Intel 82077AA FDC
    • National Semiconductor PC8477BV-1 - recommended
    • Intel N82077SL - recommended
    • Intel N82077AA - recommended, no tape support
    • Intel N82077AA-1 - tape support, FM broken
    • Intel N82077AA-5 - doesn't support 1 Mbps rate / ED disks
    • National Semiconductor PC8477AV-1 - an older version of PC8277BV-1
  • U3 - 16C550 UART
    • Most 16450/16550A type UARTs in PLCC-44 package supporting 5V operation
    • 16C550 and 16550A type UARTs from other vendors - Texas Instruments, National Semiconductor, MaxLinear, NXP Semiconductors
    • 16C650, 16C750, 16C850 type UARTs (longer FIFO)
    • 16C450, 16450, 16550 type UARTs without FIFO
  • U4 - GD75232N RS-232 Transceivers
    • Texas Instruments SN75185N, SN75C185
  • U5 - 128 KiB Flash ROM
    • Most 128 KiB Flash ROM ICs in DIP-32 package supporting 5V-only operation
    • Microchip/SST SST39SF010A, SST39SF020, SST39SF040
    • AMD Am29F010, Am29F020
    • Winbond W29EE011
    • Atmel AT29C010A
    • Greenliant/SST SST29EE010/GLS29EE010
    • 256 KiB, and 512 KiB Flash ROM ICs in DIP-32 package supporting 5V-only operation can be used as well, but are not currently supported by the built-in configuration utility and xiflash utility
    • Note that only first 32 KiB will be used regardless of the ROM capacity
  • U6 - 32 KiB or 8 KiB EEPROM
    • Atmel AT28C256, AT28C64B
  • U7 - CD74HCT688E Magnitude Comparator
    • 74HCT688
    • 74LS668, 74F521
  • U8 - U10 - SN74AHCT138N 3-to-8 Decoder
    • 74AHCT138
    • 74HCT138
    • 74ALS138, 74F138, 74LS138
  • X1
    • Any 24 MHz half can 5V oscillators
  • X2
    • Any 1.8432 MHz half can 5V oscillators

Release Notes

Changes

  • Version 1.0
    • Initial version

Known Issues

None, so far

Red Tape

Licensing

Monster FDC is an open source hardware project certified by Open Source Hardware Association, certification UID is US002072. The hardware design itself, including schematic and PCB layout design files are licensed under the strongly-reciprocal variant of CERN Open Hardware Licence version 2. The Multi-Flopppy BIOS code is licensed under GNU General Public License v3. Documentation, including this file, is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License.

CERN-OHL-2.0-S, GPL-3.0, CC-BY-SA-4.0