The M4 Board is a 2016 expansion card which enables WIFI access to and from CPC, Romboard and using SD-Card as mass storage.
You can read more about it at http://www.spinpoint.org/cpc/m4info.txt.
M4 Front View
M4 Back View
Firmware
Updating (or downgrading) a firmware is done by unpacking the update zip file to the root directory of the microSD card (from a PC). Then insert to the M4 and powercycle the CPC/M4 board, after about 20 seconds it should be updated. Verify with |version command. Latest firmware version can always be obtained via |upgrade command (no need to use PC, as long as CPC is setup to the internet).
| Version | Changes | File |
|---|---|---|
| 1.00 | Initial Version | M4FIRM_v100.zip |
| 1.01 | M4 rom defaults to Rom 6, Fix for GA 40007 | M4FIRM_v101.zip |
| 1.02 | |CD command now accepts no paramters and will prompt with cursor, so Basic 1.0 users can use SHIFT+CURSORKEYS+COPY. |
M4FIRM_v102.zip |
| 1.03 | Allow to remap entire romboard for compatiblity with XMEM. Now supporting 32 romslots. | M4FIRM_v103.zip |
| 1.04 | Ability to replace lowerrom. | M4FIRM_v104.zip |
| 1.05 | FTELL, FSIZE commands implemented and new RSX commands |ROMUP, |ROMSET, |ROMUPD |
M4FIRM_v105.zip |
| 1.06 | Fix WEB UI instability issue. Fix romupload for roms with or without AMSDOS header, and related bugs. |
M4FIRM_v106.zip |
| 1.07 | Fixes and buffering for cas_in_char, fix |ROMUP to work from .dsk files, fix cat/dir loop, fix httpget to work with IP addresses aswell as hostnames. |
M4FIRM_v107.zip |
| 1.08 | FIX IP addresses for httpget (again). Fix |dir bug. Fix hardreset. Added C_GETPATH command (requested). Added ability to load your own build of M4ROM from root of microSD, should be named M4ROM.BIN |
M4FIRM_v108.zip |
| 1.09 | Added nonblocking host & client NETAPI. Added ESC check to cat/|dir. M4 board now looks for autoexec.bas at bootup, similar to old dos machines, autoexec.bat. Make your own startup script in basic. Direct SD card sector access. Various minor fixes |
M4FIRM_v109.zip |
Various files
6128 lower rom : Modified lower rom for CPC6128 users, who cannot override amsdos (rom 7) with M4 rom, using this patched lower rom, M4 rom must be in rom slot 6. It will be initialized instead of rom 7 and provide better compatiblity with games. French version by dxs : 6128 lower rom fr
xfer (v1.0.1) : Command-line tool that allow to send files and receive from an M4 Board. Possibility to add an AMSDOS header too.
M4 Board relay rom : When moving M4rom out of position 1-7 / 1-16 it will no longer be initialized, therefore this rom should be placed at rom7 or lower. This is if you want to use 32 roms of XMEM and map M4 romboard after it. You should program the XMEM or other romboard with M4 bootrom in pos 1-7, it will look for M4 rom from 1-127 and initialize it + pass commands through to it
Technical information
Structure for romslots.bin & romconfig.bin under m4 directory are:
romslots.bin
Contains 32x raw rom data (no headers). To locate a rom in the file, use:
offset = slot * &4000
romconfig.bin
Header:
int totalRoms; // 32 (early versions of the firmware had only 16)
int m4RomNum; // M4 rom to map rom number 0-255
int m4RomEnable; // M4 rom enabled
int romRangeStart; // start mapping roms from
int lowerEnable; // lower rom replacement enabled
int lowerSlot; // which slot maps lowerrom (0-31)
unsigned int reserved[2]; // set to zero for now
Then for each rom (repeated 32 times):
char updateflag; // 0 = no rom present (or disabled), 1 = rom present (enabled), 2 = New rom will be flashed into M4 internal flash, 3 = remove rom
char name[32]; // name of rom to be displayed in webinterface
Links
Make your own M4 ROM or add additions to the existing, source code can be found here:
https://github.com/M4Duke/m4rom
It's compiled (assembled) with sdasz80 (part of SDCC package).
Various source code examples for M4 board
https://github.com/M4Duke/M4examples
CPC xfer, pc commandline tool to transfer files back and forth to M4 board:
Source code here: https://github.com/M4Duke/cpcxfer
Command documention and other infos:
http://www.spinpoint.org/cpc/m4info.txt