Author Topic: Who is able to produce a cheap ROM expansion for the CPC6128  (Read 4158 times)

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Offline TFM

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Question to all hardware freaks,
 
Who is able (and has the time) to produce a ROM expansion for the CPC.
 
Here are the specifications:
 
- 20 to 50 pieces
 
- 80 KB ROM (5 * 16 KB), if more, than great!
 
- Compatible to the CPC 6128
 
Compatibilty to 464 and 664 doesn't matter in this case. Further it doesn't matter if you use EPROM, buffered S-RAM, Flash or what ever... Further the ROM select of one ROM should be between 8 and 15, the others don't matter.
 
Please contact me (TFM) by PM to talk about anything else, if you are able and willing to build a batch of them.
 
TFM of FutureSoft
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Offline steve

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Do you mean a simple ROM board for 16kb roms or a rom simulator?
There is a 512kb battery backed ram chip with real time clock that could be used either as ram or rom.

Offline TFM

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Do you mean a simple ROM board for 16kb roms or a rom simulator?
There is a 512kb battery backed ram chip with real time clock that could be used either as ram or rom.

It doesn't matter if it is ROM or a ROM simulator. The only thing is, that is must be able to simulate at least 5 ROMs on the CPC.
 
This chip sounds really great, but my hardware skills are far from being good enought to make a small expansion out of this chip. You like to do it?
 
TFM of FutureSoft
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Offline Bryce

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I can design the circuit diagram and even do the PCB layout if you want, but I definitely don't have the time to produce them.

Bryce.

Offline MacDeath

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Can't we just use Flash Memory as Rom ?

they exist as 512K chps...and are probably the easiest to write...
But not to be used as Ram because it is said they can be written only 1 million time...

Offline steve

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@TFM/FS unfortunately I do not have the skills to design or produce this board.

@Macdeath, the advantage of the ram chip is that it is a ram chip, it does not have the limitations of flash memory, yet with battery backup built-in, it will retain it's contents for ten years without power, it also has a real time clock, so you get a 512kb memory expansion which can also work as writeable rom and a RTC.

Do the old RTC's calender still give the right days/dates, Y2K and all that? or is that a function of the software?

Offline Bryce

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The problem with the 512K RAM with battery backup RTC etc may occur when you try to address it as standard ROM. The way the CPC uses to activate or select a particular ROM is that it tries to write to an address while address-bit A13 is low, so the hardware waits for A13 and the WR signal to be low at the same time, then it reads the data bus and depending on the value there (usually 0 - 7 for most standard ROM Boards), then that particular ROM gets activated (CE pin on ROM chip gets enabled). If all of the "ROMs" are packed inside a single device, you would have to assign different areas of RAM to be the virtual ROMs and come up with hardware that would switch the addresses accordingly. I haven't seen the datasheet of this particular RAM device (anyone have a part No. available?), so I don't know how difficult this might be.

Bryce.

Offline steve

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I had a brief search for a part number and found this instead, it is a 3v part, would that be much of a problem?

AM41DL3208G offers 4MB x 8 flash rom and 1MB x8 static ram. in a 73 ball FBGA package, but if this is to be professionally manufactured we won't have to worry about soldering it ourselves  ;) , considering you get 5MB memory, the extra cost of 5v/3v interfacing should be acceptable.

EDIT: found the 512kb/RTC part number, M48T512YorV.
« Last Edit: 17:01, 23 July 10 by steve »

Offline Pentagon

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I am interested in that board too. TFM you are thinking same like me and i know what you like to do with that ;-)))

Well i am using it in the same way - just with Bdos. I need a RomBoard with 4 sockets but 5 would be fine too. And it should be intern not at exp. port.

Is that possible to do? I would sponsor the first batch with some money.

Regards
Tom

Offline TFM

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I am interested in that board too. TFM you are thinking same like me and i know what you like to do with that ;-)))

Well i am using it in the same way. I need a RomBoard with 4 sockets but 5 would be fine too.
 
And it should be intern not at exp. port. Is that possible to do?
 
I would sponsor the first batch with some money.

Hi Tompentagon,
 
Well, seems you can already imagine a lot :-)
But I don't want to take the surprise away. Keep it confidental for the moment.
First we need somebody to make the hardware.
 
If you're also interrested in a batch of such cheap ROM cards, wonderful! The more we take, the cheaper they will be.
 
If you're fine with a minimum capacity of 80 KB, then great (you can put maxam in the other 16 KB if you like).
 
However, what I need is a card for the expansion port. Becaue people shouldn't be forced to open their CPC, a lot of them just don't want. I respect this point of view.
 
Sponsoring not needed in that way. But I really appreciate.
 
Think, the more we order, the cheaper they will be. So one first and final batch will be there, if it all works well.
 
I think about 50 units for me. If you add your desired number, the price per unit will be cheaper. Let's look for the best offer.
TFM of FutureSoft
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Offline MacDeath

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Quote
yet with battery backup built-in,
Then this means additionnal components, so not that cheap card... :o

Better then to get a RAM/ROM card with both a flash ROM and a RAM...512K each, so we put the CPC to the normal limit...
 

Offline steve

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Since the amstrad can have 4MB ROM and 4MB ram, I would like a memory expansion using the new chip I found or similar.

The ram/rtc chip I suggested first probably only costs a few pounds and the battery backup is built in, so adds nothing to the final price.
« Last Edit: 21:46, 23 July 10 by steve »

Offline TFM

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Since the amstrad can have 4MB ROM and 4MB ram, I would like a memory expansion using the new chip I found or similar.

Something like this already exists. Jarek upgraded one of my CPCs to 4 MB RAM and 2.5 MB ROM (simulated by Flash).
 
Here you get all you need (ROM and FlashROM links):
 
http://8bit.yarek.pl/upgrade/cpc.cpc4mb/index.html
 
http://8bit.yarek.pl/upgrade/cpc.flash/
 
Both expansions work quite well, both are internal. Take a look.
 
 
TFM of FutureSoft
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Offline steve

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I would have to think long and hard before I started soldering wires all over my cpc6128, I would prefer something to plug into the expansion port.
Perhaps yarek might sell such a thing in the future.

Offline TFM

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I would have to think long and hard before I started soldering wires all over my cpc6128, I would prefer something to plug into the expansion port.
Perhaps yarek might sell such a thing in the future.

When I bought my intenal expansion (about 3 years ago) he was talking about an external version.
 
About soldering, I can solder nerly everything, but Jarek did that all for me. I just sended him the mother-board and got it back with a huge memory and perfectly working.
 
I can't tell the exact price I payed, because I also ordered the 8255IDE interface, but it was very, very cheap.
 
btw: The 8255IDE is the fastest ever been built for the CPC. Sorrowly I had no time to create routines for it up to now.
TFM of FutureSoft
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Offline Cholo

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I totally support (aka want to buy) any kinda Rom/ram expansion that may be produced. Taking advantage of newer technology would be preferred to getting a "large" rom/ram expansion with easy useage (perhaps SD/micro or similar accessibility?).

But has anyone ever attempted remaking or clone a Rombo Rombox? First time i opened a rombo rombox i was really surpriced by how small the thing is. Basicly its just a thin board with a few chips (making 95% of the box empty air). Its got space for 8x 16k roms and if that isnt enough then add another rombox on top and you have 16x 16k roms available. What makes the box look "large" is the eprom sockets  :)

Always had this idea in the back of my head that someone might one day release som cheap rombo-board copys at a really low price (as ive seen the c64 people selling cheap carts boards) and it dosnt even have to be as "advanced" as the rombo. When even a dummy like me can teach myslef to burn compatible £0.5 eproms using a £10 willem burner and £15 eraser .. then so can others.

Anyway, great idea.

Offline steve

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There is talk about making a 512KB cartridge for the plus machines, would it be possible to make a cartridge which had 512KB flash and 512KB ram? I know there would have to be a few extra wires coming from the computer to the cartridge, but is it possible?

Offline fano

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As we already talked, problem is there are no signals for RAM on + cartrige slot :/
"NOP" is the perfect program : short , fast and (known) bug free

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Offline steve

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Yes, that's why I mentioned "a few extra wires" which could go to a socket on the side of the cartridge, these wires might come from the expansion port.

Offline OCT

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There is talk about making a 512KB cartridge for the plus machines, would it be possible to make a cartridge which had 512KB flash and 512KB ram?
This looks like a perfect time for Prodatron to offer a batch of Symbiface II (especially now that BDOS and XDDOS have been rediscovered), for each of us who couldn't get one yet.
Or will Symbiface 3 (with Ethernet, MP3 and USB) actually ever see the light of day?
« Last Edit: 23:09, 24 July 10 by OCT »

Offline Octoate

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If you just need a ROM-Box, then why not have a look into the Wiki? There is an article about the Amstrad ROM Expander, which includes schematics.
--

Offline OCT

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I for one wouldn't mind getting a Symbiface 2, 3 all the better.
Some info and availability might help. ;D