The CPC Modular

[Bread80]

This is a new design of CPC I'm working on called the CPC Modular. My aim here is to update the CPC design for modern times and with some modern parts (e.g. SRAM in place of DRAM).

It's currently using an RC2014 Pro backplane but I'll be updating it to a custom backplane. A few notes on the design (although not everything is tested yet):
* Uses 40007 or 40010 gate array.
* 512Kb SRAM (using standard PAL/HAL for > 64k, untested).
* 512Kb NORFLASH for 31 ROMs plus firmware. Flash can be programmed in circuit (untested)
* Tape I/O jacks, keyboard and joystick connector.
* Sound uses an AY-3-8910 because they're easier to get hold of and cheaper. The extra I/O port on the 8910 is exposed via a header.
* Audio out jack. Options to send audio via the backplane either mixed or as separate channels.

I'll be open sourcing this lot shortly, but the current boards have a couple of issues to fix. And the backplane requires a few traces to be cut to fit all the signals onto it. It suggest holding off on actually building one until I've done the redesign but if you want to you're welcome.

[HAL6128]

Looks promising! Would be cool to have a modern board with original or emulated parts connected to modern HID (and should act originally)...

[d_kef]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

[abalore]

In fact it could be a very cool modular 8 bit computer, not only Amstrad, with modules for Spectrum ULA, MSX TMS9918, etc

[Prodatron]

On the C64 they have the "Tube64" project, which is very similiar:

You cannot view this attachment.

Every PCB is one component of the whole computer system (CPU, SID, VIC2, Ram etc.).

https://www.forum64.de/index.php?thread/108496-tube64/&pageNo=9

[Bread80]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

[Bread80]

In fact it could be a very cool modular 8 bit computer, not only Amstrad, with modules for Spectrum ULA, MSX TMS9918, etc

I'm not sure how much would be reusable for other machines as they're all pretty unique in their architectures. Maybe the CPU, ROM and backplane though.

And there's already a couple of modular MSX projects. This one is from Sheila Dixon: https://hackaday.io/project/190408-msx-on-rc2014
I think this is the other one: https://github.com/vipoo/yellow-msx-series-for-rc2014

Sheila has also made a replacement for the MSX display chip using an RP2040.

[Bread80]

On the C64 they have the "Tube64" project, which is very similiar:

Ooh. That's lovely. I've not come across that one before.

[Bread80]

If anyone is interested I've now open-sourced the project. As noted above the project currently has bugs will be undergoing a major format change. The keyboard is a separate project and I'll work to release that shortly.

https://github.com/Bread80/CPCModular

[GUNHED]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

Would be nice to have this ASIC expanded from 15 to 255 sprite colors (the space is there. only 4 bits are used of each 8 bit for every dot in the sprite data area). Well, of course it would need to double the internal RAM of the ASIC. Just an idea.

[andycadley]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

Would be nice to have this ASIC expanded from 15 to 255 sprite colors (the space is there. only 4 bits are used of each 8 bit for every dot in the sprite data area). Well, of course it would need to double the internal RAM of the ASIC. Just an idea.

Well you'd also have to find space for another 239 palette registers. 

I'm not sure that's how I'd use those bits if I were enhancing the Plus models though. Better options might be alpha transparency or the ability to mark pixels as appearing "behind" screen colours somehow. 

[genesis8]

If anyone is interested I've now open-sourced the project. As noted above the project currently has bugs will be undergoing a major format change. The keyboard is a separate project and I'll work to release that shortly.

https://github.com/Bread80/CPCModular

Hi,

put at least a photo at the top of readme.md, more sexy !

[GUNHED]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

Would be nice to have this ASIC expanded from 15 to 255 sprite colors (the space is there. only 4 bits are used of each 8 bit for every dot in the sprite data area). Well, of course it would need to double the internal RAM of the ASIC. Just an idea.

Well you'd also have to find space for another 239 palette registers.

I'm not sure that's how I'd use those bits if I were enhancing the Plus models though. Better options might be alpha transparency or the ability to mark pixels as appearing "behind" screen colours somehow.

That would mean a completely new chip instead of a couple of RAM bytes more.

[abalore]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

Would be nice to have this ASIC expanded from 15 to 255 sprite colors (the space is there. only 4 bits are used of each 8 bit for every dot in the sprite data area). Well, of course it would need to double the internal RAM of the ASIC. Just an idea.

I find also interesting to expand the CPC palette to 32 colors, the bit provision for it already exists in the GA. 

[zhulien]

That's a really great idea! Thanks for open sourcing it.
Are there also plans for an ASIC module?

d_kef

Do you mean ASIC as in the Plus models or the gate array? If it's the latter I have a prototype working replacement using a pair of RP2040 (RPi Pico) which needs miniaturising and finishing off.

Would be nice to have this ASIC expanded from 15 to 255 sprite colors (the space is there. only 4 bits are used of each 8 bit for every dot in the sprite data area). Well, of course it would need to double the internal RAM of the ASIC. Just an idea.

I find also interesting to expand the CPC palette to 32 colors, the bit provision for it already exists in the GA.

If there are additional bits in the GA are they actually working bits or dormat?

If you were to use the additional bits of asic as e.g. transparency, then you may be able to have an internal genlkke capability of other functional ability to have additional optional screens behind without breaking backward compatibility as long as the behind screens are purely cosmetic.

[andycadley]

If there are additional bits in the GA are they actually working bits or dormat?

There aren't any actual "bits", it's just gaps in the address space or decoding where, if you were designing a more advanced chip, you could theoretically put additional functionality without altering existing behaviour. 

[Bread80]

put at least a photo at the top of readme.md, more sexy !

Done. Thanks for the nudge. I've also done a bit more tidying up of the readme.

[Bread80]

If you were to use the additional bits of asic as e.g. transparency, then you may be able to have an internal genlkke capability of other functional ability to have additional optional screens behind without breaking backward compatibility as long as the behind screens are purely cosmetic.

The limitation on the pallette is the output pins of the gate array. Three pins (R,G,B) each of which can have three levels. 3^3 = 27. Use a different form of output and, yes, you could have a few more colours.

[GUNHED]

Exactly! 

[zhulien]

On the C64 they have the "Tube64" project, which is very similiar:

You cannot view this attachment.

Every PCB is one component of the whole computer system (CPU, SID, VIC2, Ram etc.).

https://www.forum64.de/index.php?thread/108496-tube64/&pageNo=9

That's something that could end up like an Apple Trash Can if they aren't careful