Author Topic: RC2014 bus card for Sam Coupe - possible on CPC also?  (Read 1104 times)

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Offline zhulien

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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?

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Offline Gryzor

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #1 on: 14:28, 14 September 21 »
What would you connect through it?

PS Quazar does really nice things for the SAM...
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Offline Bryce

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #2 on: 16:51, 14 September 21 »
It's just a plane breakout board. We already have one. It's called an MX4 and you can buy them from @TotO (I already have one :) ).

Bryce.
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Offline genesis8

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #3 on: 22:13, 14 September 21 »
Or the LambdaBoard with 3 slots : https://github.com/lambdamikel/LambdaBoard
Or the CPCConnector with 1 slot : https://github.com/lambdamikel/CPCConnector
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Offline revaldinho

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #4 on: 00:03, 15 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 and other third party ones too like this TMS9918 VDP.
Were you interested in any in particular for the CPC?



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Offline zhulien

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #5 on: 17:57, 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
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Offline eto

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #6 on: 18:28, 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.
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Offline zhulien

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #7 on: 18:40, 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.


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.
« Last Edit: 18:54, 15 September 21 by zhulien »
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Offline zhulien

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #8 on: 18:47, 15 September 21 »
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."
« Last Edit: 18:51, 15 September 21 by zhulien »
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Offline GUNHED

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #9 on: 19:48, 15 September 21 »
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  :-\ ).
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Offline Bread80

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #10 on: 12:20, 22 September 21 »
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?
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Offline TotO

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #11 on: 12:27, 22 September 21 »
that 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.
« Last Edit: 12:57, 22 September 21 by TotO »
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Offline zhulien

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #12 on: 11:50, 28 September 21 »
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.
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Offline Bread80

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #13 on: 19:20, 05 October 21 »
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)

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Offline zhulien

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #14 on: 17:17, 08 October 21 »
that's pretty awesome.  add me down for 4 of them when you have it working... (prefer not in kit form)
« Last Edit: 17:21, 08 October 21 by zhulien »
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Offline Bread80

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Re: RC2014 bus card for Sam Coupe - possible on CPC also?
« Reply #15 on: 20:10, 11 October 21 »
that'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).
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