Author Topic: Amstrad PCW RTC  (Read 237 times)

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Offline torrind

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Amstrad PCW RTC
« on: 01:19, 25 December 18 »
Hi Folks,


Firstly, Merry Christmas - Hope you all get everything you want.... ;D


What I'd like Father Christmas to bring me is a RTC addon for my PCW8256 - I've found instructions to build one in German, but this isn't much good to me.


Do any of you good people have any ideas / suggestions how easy this is to achieve?


As always, your suggestions are most welcome...


Regards,


Darren

Offline JonB

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Re: Amstrad PCW RTC
« Reply #1 on: 15:18, 25 December 18 »
Hi Darren

Not too tricky. An 8 bit address decode using a comparator chip and a DS1302 RTC, followed by code to read / write the RTC and a small "run and exit" FID to set the system time at bootup. Needs a latch, too, I think. With this you'd have 8 GPIO pins and 3 are needed by the RTC - so the other 5 pins you could use for other purposes.

The main problem will be connecting this to the PCW (use a Z80 shim, maybe) and the cost of the components. The rest of it is straightforward. If you have a uIDE installed it would be even easier, but you need to design / build a PCB.

Let me think a bit. Sounds like a useful project.
« Last Edit: 11:29, 26 December 18 by JonB »

Offline torrind

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Re: Amstrad PCW RTC
« Reply #2 on: 22:11, 26 December 18 »
Thanks Jon -


That would be most appreciated.


I don't have a uIDE, although I'd love one...




Darren

Offline GeoffB17

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Re: Amstrad PCW RTC
« Reply #3 on: 01:16, 27 December 18 »
Hmm, no idea about the how, but I'd find one pretty useful.   I had one, and it was a help.

The one I had was an add-on - or should this be an add-in - for the CPS8256 unit.   You needed to upen up the box, prise out the SIO chip (I think it was that one, add in the extra card which included the battery and the clock chip, and then plug the SIO chip back into the new socket).   All went OK, it worked fine.   I had quite a few disks set up to expand the DIR info for date/times, this was useful when I was programming.   I don't think it's working now, as the battery has gone from lack of use.   Or maybe it DID still work, but did not keep any change for very long?

The problem NOW is that the expansion slot is not available for the CPS box, as it's occupied by Jon's uIDE connector which is much more important.   So how to get around that?   If Jon can get around that??

Just found the little doc for the thing.   It was the SCA Real Time Clock Module.   You needed to remove the 'Z80 DART' chip, not sure if that's the same as the SIO?   No need to refit the removed component, the card must have had a new one fitted.   The package includes a prog, TIME.COM, to obtain or set the time stored, plus GETCLOCK.BAS which allows BASIC to access the system time/date.

I'll keep my fingers crossed.   After all, it IS Christmas!!

Geoff
« Last Edit: 01:28, 27 December 18 by GeoffB17 »

Offline JonB

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Re: Amstrad PCW RTC
« Reply #4 on: 10:22, 27 December 18 »
Hmm, well, I am trying to think of the best / most cost effective way to implement it.

The lazy way would be to use the address decoding mechanism of the uIDE (comparator) and bolt a RTC onto it. I'd have to build it so that the uIDE plugged into it. Either that or you'd need to use something like the Z80 bus card I proposed.

Geoff, you ought to use a Z80 shim if you need access to the expansion port...