A project to turn a Raspberry Pi into a SPI Connected Second Processor for the Acorn MMC Micro Model B or Master 128.
See:http://stardot.org.uk/forums/viewtopic.php?f=3&t=10421
| Command | Description |
|---|---|
| *HELP ARM | Displays the current version and list of commands |
| *GO | Executes code at the given address in user mode |
| *MEM | Displays memory in hex and ascii |
| *DIS | Disassembles memory |
| *FILL | Fills a block of memory |
| *CRC | Calculates the "Atom" CRC over a block of memory |
| *TEST | Does nothing of significance |
| From | To | Size | Description |
|---|---|---|---|
| 00000000 | 0000003F | 64B | ARM vectors |
| 00008000 | 00008EFF | ~4KB | Basic workspace |
| 00008F00 | 001FFFFF | ~2MB | Basic program storage |
| 00200000 | 01F2FFFF | ~29MB | Unused |
| 01F30000 | 01F3FFFF | 64KB | Undefined Instruction Stack |
| 01F40000 | 01F4FFFF | 64KB | Abort Stack |
| 01F50000 | 01F5FFFF | 64KB | User Stack |
| 01F60000 | 01F6FFFF | 64KB | IRQ Stack |
| 01F70000 | 01F7FFFF | 64KB | Supervisor Stack |
| 01F80000 | 01FFFFFF | 512KB | Tube Client OS |
| 02000000 | 0FFFFFFF | 224MB | Unused |
Notes:
- PAGE = 00008F00
- HIMEM = 00200000
Currently the BASIC 135 executable loads to 0xF000, which is in the middle of the program area, and will cause problems for large programs.
The only reason for this is that MMFS seems to ignore the higher order bits of the address, and we are currently just using *RUN.
In fact, in DFS there are only two higher order bits, so the max load address is not significantly larger anyway.
Eventually BASIC should be a relocateable module. Until then, it might be worth writing a small boot loader.
Note: *LOAD BAS135 00200000 does work.
Putting them at just below 32MB was completely arbitrary.
Again, placing HIMEM at 2MB was completely arbitrary.
- Implement the SWI X flag to have errors returned in a Error Block
- SWI OS_Exit should accept params in R0,R1 and R2
- SWI's OS_IntOn and OS_IntOff currently broken
- Run time debug level settings
- Commands to enable/disable the Caches
- Port JGH's Module Handling: http://mdfs.net/User/JGH/Develop/ARMCoPro/Modules/
- Address possinle IRQ Stack Memory Leak
- Provide an option for soft vs hard reset. Possibly this could be configured on the "boot command line"
- Vectors - currently we don't implement any vectors. Then implement OS_Claim and OS_Release.
- Implement more SWIs, especially
- OS_SynchroniseCodeAreas (SWI &6E) (called by BASIC)
- OS_Mouse
- OS_Byte 82-84 (read memory limits)
- OS_ReadEscapeState
- OS_ExitAndDie
- OS_ReadMemMapInfo
- OS_ValidateAddress
- OS_LeaveOS
- OS_ReadLine32
- The set that Sprow implements is a good target: http://www.sprow.co.uk/bbc/hardware/armcopro/armtubeoscalls.pdf