New yerar, new CPC board

[Piotr]

Upss , price is for PCB only, no components no assembled of course. Is not obvious for the price?

[Munchausen]

It seemed clear to me. I wouldn't intend to make 3 boards immediately, but am looking for two spares for future projects I have in mind, as it isn't clear that they would be available into the future. The DIY aspect is fine for me, and should save Piotr some time and effort too

[Joseman]

It's totally clear for the price, i'm fine with that. soldering time!! 

About testing the 464 board without FDC, i don't have any external DDI controller, i think it's nearly useless test this way the board 

The cpc6128 clone is other thing! i think in test this board to the end of time 

but if it is totally necessary i can help then

[fatbob]

I am interested in 1 PCB.

[TotO]

Upss , price is for PCB only, no components no assembled of course. Is not obvious for the price?

May be not enough obvious when an used CPC is sold less than 50€.
So, I prefered that you clarify the situation as most peoples don't have soldering skill. 

[Piotr]

TotO, btw where is my disk interface for CPC?? I'm waiting and waiting?

[TotO]

TotO, btw where is my disk interface for CPC?? I'm waiting and waiting?

You missed it today...

[Munchausen]

@Piotr I had a thought - why don't you use smaller RAM chips with 4 or 8 bits instead of the 1 bit RAM in the 464/6128? You could save a lot of space.

The 6128 plus uses 4 bit RAM so you only need 4 RAM chips instead of 16... you could use the same as the plus (41464) or even 8 bit RAM so you would only need two chips. I think it doesn't require any other changes to the schematic than just wiring the 8 data lines that normally go to 8 separate chips to a single one (or two in the case of 41464)!

[radu14m]

what would be the price for a complete cpc, not only the board ?
I would like also the ideea of a building kit like a DIY

[Piotr]

In next weekend i do some test with SRAM memory replacement . Low power consumption and more space on board.
Complete CPC, no idea to be honest i don't have time to assembly it. I made lot's other extensions

[CraigsBar]

I'd love a board please.

[ralferoo]

Hi Piotr,

I've only just noticed this thread, looks good...

As has been suggested, I'd definitely suggest looking at SRAM - you can even get them in large old style packages, for example a very early prototype of mine: CPC FPGA: SRAM board - the SRAM chip is the big huge thing!

The advantage of the SRAM is that it's relatively big (512KB in this case), cheap (around €5 in single unit quantities in this case) and is 8-bit so you can simplify your design a lot. It'd also allow you to overclock your board as it'll happily run at up to 16MHz (I think it's actually specified at around 18MHz).

This particular one is 3.3V, but you can still get 5V ones but they do cost a little more. Probably easier to source than a bunch of 4164s though...

Anyway, looking good. Even though I prefer FPGAs for their reconfigurability, it's really nice to see an oldschool design with lots of DIP chips placed very compactly. Great work!

Cheers,
    Ralf.

[acf76]

I am interested in 1 PCB.

[Piotr]

MY favourite as6c4008 I monthly use over a 50-70 this chips.
I made Sram for Speccy, small module what replace 8x3264 upper ram.

[Piotr]

But in this board, like in orginal lines Din and Dout from memory is separated so i need do a multiplexer for SRAM  i think ?

[Joseman]

Only one question, yes i know that i'm a little paraonid with that 

Can we ensure a 100% compatibility with the original chips?

and i mean, speed, behavior... the refresh thing on the CRTC and Z80...

Bad memory emulation it's like a bad memory module at all, a lot of sofware will crash or be inestable or be erratic...

[Piotr]

Is any software to test? i watching lots of demos and all looks fine ? But maybe i'm wrong? ALso on board is orginal chips so
zaxoniec - YouTube

[Joseman]

Is any software to test? i watching lots of demos and all looks fine ? But maybe i'm wrong? ALso on board is orginal chips so
zaxoniec - YouTube

I meant with SRAM chips! or 8bit chips!

I really afraid of modifications on the original design...

Even Amstrad screwed up with the plus range 

[Piotr]

This is a one more reason why first i build prototype, i connect it and check it practically

[Joseman]

This is a one more reason why first i build prototype, i connect it and check it practically

I always wonderer why there isn't a memtest type program on cpc?

Memtest86+ - Advanced Memory Diagnostic Tool

[Munchausen]

I always wonderer why there isn't a memtest type program on cpc?

Memtest86+ - Advanced Memory Diagnostic Tool

There is, but I forget where to find it. A good idea!

However I think you shouldn't worry - using a different RAM is not really something that can fail in some intricate way causing some subtle different behaviour, it will basically either work or not!

[Joseman]

@Piotr the FDC connector will be a standard 34 pin PC connector to allow connect directly a 3.5" PC floppy drive?

I don't think that for this board the use of an old 3" disk drive will be reasonable... and even then, you can make a conversor cable (like the same cable that we made for the 3,5" drives  )

[Piotr]

34 pins, i just copy paste DDI clone to project.

[Joseman]

34 pins, i just copy paste DDI clone to project.

How is managed the ready signal? or it relay in enabling the ready signal on the the pc floppy itself?

[The Last Bandit]

Probably interested in one of these as well when they are ready, its not like I don't have enough soldering to be doing..


Tough job avoiding the inevitable feature creep