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lfantoniosi / tn_vdp

Tang Nano 9K TMS 9118A VDP
BSD 3-Clause "New" or "Revised" License
120 stars 23 forks source link

Switching between 80 and 40 column mode? #18

Open alitel opened 9 months ago

alitel commented 9 months ago

This is more a question than an issue -- I'm wondering if the code used to switch text mode columns under cpm on the nabu is available? (eg whatever is used in the nabu cpm images provided in this repo which set the vdp to 80 columns on boot). I'd like to write (or hey, acquire!) a utility to switch text modes in cpm on the nabu between 40 and 80 columns similar to how the color.com utility switches colors. I'm working with the z88dk f18a extension, but I'm not sure if this project is 100% compatible. Even information on how the VDP control register bits should be set would be very helpful!

Cheers and thank you!

lfantoniosi commented 9 months ago

Did you check the readme ? I put cp/m 80 column images there but no, it does not switch between 40/80 because it had to patch the existing windowing system.

https://github.com/lfantoniosi/tn_vdp?tab=readme-ov-file

On Thu, Feb 29, 2024 at 9:05 PM alitel @.***> wrote:

This is more a question than an issue -- I'm wondering if the code used to switch text mode columns under cpm on the nabu is available? (eg whatever is used in the nabu cpm images provided in this repo which set the vdp to 80 columns on boot). I'd like to write (or hey, acquire!) a utility to switch text modes in cpm on the nabu between 40 and 80 columns similar to how the color.com utility switches colors. I'm working with the z88dk f18a extension, but I'm not sure if this project is 100% compatible. Even information on how the VDP control register bits should be set would be very helpful!

Cheers and thank you!

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alitel commented 9 months ago

Yes, it's that patching that I'm interested in -- is the source (e.g. the .asm or .z80 files) code implementing the patch available anywhere? I'd like to re-create the ability to switch modes for a different cpm build, so I am just looking for information on how the mode switch is done in code (disassembllng the binaries and hunting through that code is, I find, brutal lol)