PHC-25 : BASIC ROM informations

[VFD]

I did a brief analysis of the PHC-25's BASIC ROM. This should help with documenting the ROM's source code.
Each character on the PHC-25 is encoded using 12 bytes.

Here’s how the character data is organized:

• Control ASCII: &H00 to &H1F → stored from &H4FEC to &H516B
• Standard ASCII: &H20 to &H7F → stored from &H516C to &H55EB
• Extended ASCII: &H80 to &HFF → stored from &H55EC to &H5BEB

From &H5BEC to &H5FFF, all bytes should be replaced with &H00.
I made some modifications, and it works.

You can find more on my GitHub about the PHC-25.

https://github.com/VFD/SanyoPHC25/

[suborb]

Thanks, I did find a more complete ROM disassembly when adding support for the PHC-25. I seem to have mislaid the link though.

However, in the end it was just easier to cut out the firmware - the im1 routine uses the alternate register set to avoid saving the primary set which causes all sorts of trouble with longs and floats.

Our journey to supporting can be found here: z88dk/z88dk#836 and on a forum post.

[VFD]

I've rewrite the end of the ROM.
All ASCII charset.

From 5BEC to 5FFF, all to 00.
This part is a mistake from SANYO (no code just dust), I'm hacking the ROM to put some code here.
I'm building an alternate rom.

Some other DB to put in the code later.

I've just upload on my repo the new ASM i've just modified.