I saw this RC2014 bus card for Sam Coupe on ebay.
https://www.ebay.co.uk/itm/113959744930?hash=item1a8887b5a2:g:NtgAAOSw8Uddx~Lv
Is it easily possible to do this on CPC also?
What would you connect through it?
PS Quazar does really nice things for the SAM...
It's just a plane breakout board. We already have one. It's called an MX4 and you can buy them from @TotO (https://www.cpcwiki.eu/forum/index.php?action=profile;u=290) (I already have one :) ).
Bryce.
Or the LambdaBoard with 3 slots : https://github.com/lambdamikel/LambdaBoard (https://github.com/lambdamikel/LambdaBoard)
Or the CPCConnector with 1 slot : https://github.com/lambdamikel/CPCConnector (https://github.com/lambdamikel/CPCConnector)
Quote from: zhulien on 12:05, 14 September 21
I saw this RC2014 bus card for Sam Coupe on ebay.
https://www.ebay.co.uk/itm/113959744930?hash=item1a8887b5a2:g:NtgAAOSw8Uddx~Lv
Is it easily possible to do this on CPC also?
Yes, is the short answer. None of the MX4 backplanes mentioned above let you plug RC2014 cards directly into a CPC which was surely the original question.
Building a backplane with the RC2014 bus pin out for the CPC would be easy but needs a little additional decoding logic. Looking at the kicad schematics for a couple of the IO modules it looks like they only decode the low address byte of IO addresses. So, for the CPC you'd need to pick a 'safe' high byte in the memory map and decode that too, to enable the IOREQ* signal to the bus.
And then port any drivers to the CPC of course. But that would be part of the fun of it, right ?
There are lots of modules, all available as kits, on the main RC2014 site (https://rc2014.co.uk/modules/) and other third party ones too like this TMS9918 VDP (https://hackaday.com/2018/06/22/theres-rc2014-life-in-the-tms9918a-display-chip-yet/).
Were you interested in any in particular for the CPC?
Given the number of cards available, it could be a cool addition - especially if it can be daisy changed with or without a Mx4
Quote from: zhulien on 15:57, 15 September 21
Given the number of cards available, it could be a cool addition - especially if it can be daisy changed with or without a Mx4
which of the cards is of any interest and doesn't already exist in some way for the CPC?
and, if I understand that right, none of the cards will be usable without a bit of modification due to how the CPC addresses extensions compared to a normal Z80 computer.
Quote from: eto on 16:28, 15 September 21
which of the cards is of any interest and doesn't already exist in some way for the CPC?
and, if I understand that right, none of the cards will be usable without a bit of modification due to how the CPC addresses extensions compared to a normal Z80 computer.
- the already mentioned gfx card, surely cheaper than a v9990 but still an interesting option and more cards here too https://www.tindie.com/stores/mfkamprath/
- another sounds card not as good as playcity, but cheaper https://www.tindie.com/products/semachthemonkey/ym2149-sound-card-for-rc2014-retro-computer/
- there are already backplanes too so perhaps just a small adapter could be used between cpc and rc2014 backplane or between mx4 and rc2014 backplane. https://rc2014.co.uk/backplanes/
- another PI as a coprocessor board or even use it as it was supposed to be, a terminal for text output https://rc2014.co.uk/modules/pi-zero-serial-terminal/
- blinkenlights https://rc2014.co.uk/modules/other-modules/blinkenlights/
- another wifi option? https://rc2014.co.uk/modules/esp8266-wifi-module/
my thoughts are... mostly the CPC-specific hardware is really good because it takes advantage of aspects of the CPC - but... the RC2014 as an option can sometimes be a cheaper option or just makes some things available that aren't yet created on the CPC - seems a fairly popular z80 platform, perhaps the most popular of recent years? Perhaps spectrum is more popular? but i don't see a lot of new cool hardware coming out for spectrum.
https://www.tindie.com/products/mfkamprath/tms9918a-video-card-kit-for-rc2014/ that is a LOT cheaper than a v9990
https://www.youtube.com/watch?time_continue=9&v=x5GBww5yQh8&feature=emb_logo
https://en.wikipedia.org/wiki/Texas_Instruments_TMS9918
(no-where near as powerful though)
"Texas Instruments' TMS9918A was succeeded by Yamaha's V9938, which added additional bitmap modes, more colorful sprites, a vertical full-screen scroll register, vertical and horizontal offset registers, a hardware blitter and a customizable palette. The V9938 was designed for the MSX2 standard of computers, and later used in a third-party upgrade to the TI-99/4A — the Geneve 9640 'computer-on-a-card'. The V9938, in turn, was succeeded by the V9958, which added some additional high-colour modes and a horizontal two-page scroll register. These chips were used in the MSX2+/turboR systems, as well as on the "TIM" upgrade card for the TI-99/4A, although rumor has it that the V9958 was also used in a generation of the Photo Play arcades. Yamaha also produced a V9990, which is considered the follow-up of the V9958 by some,[who?] but it is not backwards compatible."
Anything we don't already have as add-on for the CPC?
(Pricing shall not be the problem for CPC expansions. Just remember what you pay for your PC cards :-\ ).
As others have said, easy to do, but the I/O port addressing is the challenge. RC2014 modules only (usually) use address line A7 to A0, whereas CPC stuff seems to partially decodes lines A15-A8 as device enable and A7-A0 as register select.
My suggestion would be fully decode A15-A8 on the expansion board and then gate (probably just) /IORQ to the RC2014 slots so the boards will only receive the /IORQ signal when the correct high-byte is used.
In which case, does anyone have any suggestions as to what port address to use?
Quote from: zhulien on 16:47, 15 September 21that is a LOT cheaper than a v9990
Sure, and fully compatible with many existing systems like SG-1000, Coleco, MSX, MSX2, ...
I have done a V9958 video board prototype for the CPC around 5/6 years ago, and it cost me 15€ to done it.
i think such an msx gfx card is a good justification - one could be made custom - but if using the existing commercial one then whatever their efforts or alternatives might be in future potentially we would be able to use. I think it would make quite a few MSX and Sega SC3000 games easier to port, because unless you are doing shoddy spectrum -> CPC ports where you effectively try write a spectrum attribute emulator (ignore them all and make it monocrhome), the porting of games in general is quite involved - you would need to change the games hopefully optimised data structures from tiles and sprites to memory mapped bitmaps and lose all the speed in the process. Sega SC3000 alone has over 100 titles (on cart and card) - i am unsure what the crossover is between the two formats - but even if there are 75 new titles that could be ported - that would be pretty awesome.
Is this what anyone was thinking of?
I've added:
3x MX4 slots
3x RC2014 slots
address decoding for A15..A8 with solder links so the address can be modified
optional power in via USB type B socket
power LED (for the USB power)
reset button (for the whole CPC)
that's pretty awesome. add me down for 4 of them when you have it working... (prefer not in kit form)
Quote from: zhulien on 15:17, 08 October 21that's pretty awesome. add me down for 4 of them when you have it working... (prefer not in kit form)
Will do.
I'll probably get the prototype printed up in the next month or so (I tend to batch up my PCB orders to save on postage).