New V9958 based RC2014/RCBus module

[Dean Netherton]

Happy new year everyone.

I have been doing my best to 'ignore' the world's madness - by designing some new modules.

I started to wonder if I could redesign my Yellow MSX modules, to instead of using PCBs of around 8 cm height -- see if I could fit them in a more conventional height of around the 5cm.

I started with the V9958 module - its a bit extreme as the V9958 chip with its 64 PINS takes up about half of a conventional module's height - so with RAM and other support stuff - its be a bit of a challenge.

I solved this, by only having 64K RAM on the PCB, and designing an expansion board to allow for more memory.  The advantage of the expansion board, is that I can then extend the vram size to the V9958's maximum of 192K of VRAM.

So I kind of traded length for width!  Oh matron indeed!

And here it is in all its 'glory'.

do you like?

https://www.dinoboards.com.au/stegosaur/v9958/

Dean

[Wayne Warthen]

This is very nice Dean.  I really like the form factor that now conforms to a normal RCBus card.

I assume that typical use in RomWBW would not require the expansion board, right?

If I can find some time, I will build one of these, but likely to be a while based on the current priority list.

Thanks, Wayne

[Dean Netherton]

Thanks Wayne,

> I assume that typical use in RomWBW would not require the expansion board, right?

Certainly.  As RomWBW only needs text modes (compatible with the TMS9918), very little memory is needed.

Having said that, I think a regression with RomWBW's support for the chip might have been introduced recently.  I was testing the module last night, and when I pull the latest code, I noticed a problem where it appears memory (font and screen) is not initialised (earlier code was working just fine)

I will look at it today - I plan to try and find the specific commit/commits - and hopefully send through a PR.

Dean.

[Wayne Warthen]

Hi Dean,

On Monday, January 5, 2026 at 1:14:19 PM UTC-8 dean.ne...@gmail.com wrote:

Having said that, I think a regression with RomWBW's support for the chip might have been introduced recently.  I was testing the module last night, and when I pull the latest code, I noticed a problem where it appears memory (font and screen) is not initialised (earlier code was working just fine)

I will look at it today - I plan to try and find the specific commit/commits - and hopefully send through a PR.

Odd.  I will also try to look at this, but it will be tomorrow at the earliest.

Thanks, Wayne