bbz - Acorn MOS for 6502 adaptation layer

Used to run 6502 programs using the Acorn MOS on a modern operating system as a console application. It runs BBC Micro language ROMs.

What is this

This is a MOS for 6502 execution environment. It's a 6502 emulator that intercepts the calls to the Acorm Machine Operating System (MOS) and services them as a native console application on the host.

This is not a BBC Micro emulator. It does not emulate the BBC Micro hardware, just the 6502 processor.

BBZ is a console program, it tries to look and feel as a modern console application not as a BBC Micro. There is command history accesible with the up arrow and control-R. Control-C behaves as the BBC Micro Escape key to interrupt long running programs. Control-C twice will exic BBZ back to the host.

This program is heavily inspired on Applecorn, "a ProDOS application for the Apple //e Enhanced which provides an environment for Acorn BBC Microcomputer language ROMs to run."

References:

BBC Microcomputer System User Guide
The Advanced User Guide for the BBC Microcomputer
BeebWiki - 8-bit Acorn Computer Wiki
Applecorn source code
The MOS Reassembly for the BBC Micro and raybellis's mos120
beeb-fstest test suite

Features

Can run BBC BASIC and most of the language ROMs.
Saves and loads files from the host filesystem.
Readline like input with persistent history.
Can load up to 16 sideways ROMs, the unused slots are filled with sideways RAM 16K expansions.
Most of the MOS entrypoints and VDU control codes are defined.
Does some of the mode 7 text coloring using ANSI escape codes on the terminal. Try VDU 65,129,66,130,67,132,68,135,69,13,10 on BBC BASIC.
OSCLI comands suported:
- *| */ *FX *BASIC *DELETE *DIR *EX *HELP *INFO *LOAD *RUN *SAVE *SPOOL *TYPE
- *CAT filename: dumps the file contents using the BBC Micro character set and VDU conversions
- *HOST cmd: execute a command on the host OS. Example: *HOST ls -la
- **BYE or *QUIT: exit to host
- *ROMS: List the loaded ROMs
6502 emulation provided by iz6502

Usage

bbz [flags] [filename]

filename is the filename of the ROM to run (the same as -rom0). By default, it uses the BBC Basic ROM in BASIC.ROM.

AvaIlable flags (to put before the ROM filename if present):

  -M	dump to the console the MOS calls including console I/O calls
  -c	dump to the console the CPU execution operations
  -m	dump to the console the MOS calls excluding console I/O calls
  -p	panic on not implemented MOS calls
  -r	disable readline like input with history
  -s	dump to the console the accesses to Fred, Jim or Sheila
  -rom0 string
    	filename for rom 0 (slot 0xf)
  -rom1 string
    	filename for rom 1 (slot 0xe)
  -rom2 string
    	filename for rom 2 (slot 0xd)
  -rom3 string
    	filename for rom 3 (slot 0xc)
  -rom4 string
    	filename for rom 4 (slot 0xb)
  -rom5 string
    	filename for rom 5 (slot 0xa)
  -rom6 string
    	filename for rom 6 (slot 0x9)
  -rom7 string
    	filename for rom 7 (slot 0x8)
  -rom8 string
    	filename for rom 8 (slot 0x7)
  -rom9 string
    	filename for rom 9 (slot 0x6)
  -rom10 string
    	filename for rom 10 (slot 0x5)
  -rom11 string
    	filename for rom 11 (slot 0x4)
  -rom12 string
    	filename for rom 12 (slot 0x3)
  -rom13 string
    	filename for rom 13 (slot 0x2)
  -rom14 string
    	filename for rom 14 (slot 0x1)
  -rom15 string
    	filename for rom 15 (slot 0x0)

Install

From binary

Get the latest version from the releases page in Github

From source

bbz is a standard go project, build with go build .

From the Snap store

bbz is named mosbbz in the Snap store:

$ sudo snap install mosbbz

You will need to download a ROM, for exmaple BASIC.ROM, and invoke as mosbbz':

$ mosbbz BASIC.ROM

Usage examples

Running BBC Basic:

$ ./bbz
bbz - Acorn MOS for 6502 adaptation layer, https://github.com/ivanizag/bbz

BASIC

>PRINT "HELLO"
HELLO
>10 PRINT "HEY"
>RUN
HEY
>SAVE "TEST"
>NEW
>LOAD "TEST"
>LIST
   10 PRINT "HEY"
>X

Mistake
>*HOST ls -l TEST
-rw-r--r-- 1 casa casa 14 jul 30 20:04 TEST

>^Csignal: interrupt

Log of the MOS calls (excluding the most verbose output API calls):

$ ./bbz -m ROMs/Forth_103.rom
bbz - Acorn MOS for 6502 adaptation layer, https://github.com/ivanizag/bbz

FORTH

COLD or WARM start (C/W)? C
[[[OSRDCH()=0x43]]]
[[[OSARGS('Get filing system',A=00,Y=00) => 105]]]
[[[OSBYTE82('Read machine high order address',X=0x58,Y=0x00) => (X=0xff,Y=0xff)]]]
[[[OSBYTE84('Read top of user mem',X=0x58,Y=0x00) => (X=0x00,Y=0x80)]]]
[[[OSBYTE83('Read bottom of user mem',X=0x58,Y=0x00) => (X=0x00,Y=0x0e)]]]


FORTH
OK
2 1 + .
[[[OSWORD00('read line',BUF=0x0542,range=20-ff, maxlen=80)='2 1 + .']]]
3 OK

Using mode 7 colors:

Using several ROMs at once:

$ ./bbz -rom0 BASIC.ROM -rom1 ROMs/Forth_103.rom -rom2 ROMs/LISP501.ROM -rom3 ROMs/COMAL.rom -rom4 ROMs/MPROLOG310.rom -rom5 ROMs/Pascal-1.10-Compiler.rom -rom6 ROMs/Pascal-1.10-Interpreter.rom
bbz - Acorn MOS for 6502 adaptation layer, https://github.com/ivanizag/bbz
(tip: uppercase is usually needed)

BASIC
>*ROMS
ROM F BASIC 01 (L)
ROM E FORTH 01 (SL)
ROM D LISP 05 (SL)
ROM C COMAL 16 (SL)
ROM B micro PROLOG  80 (SL)
ROM A Pascal 10 (SL)
ROM 9 Pascal 10 (SL)
RAM 8 16K
RAM 7 16K
RAM 6 16K
RAM 5 16K
RAM 4 16K
RAM 3 16K
RAM 2 16K
RAM 1 16K
RAM 0 16K
>*HELP

BBZ 0.0

FORTH 1.03

LISP 5.01

COMAL

micro PROLOG 3.1

PASCAL 1.10
>*LISP
LISP



Evaluate : (* '*FORTH)
FORTH


COLD or WARM start (C/W)? C


FORTH
OK
OS' *COMAL'
COMAL

→*PASCAL
Pascal

%*PROLOGUE
micro PROLOG 

29184 bytes free
&.