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Re: DIY RAM EXPANSION
Posted: Thu Jul 28, 2022 6:40 pm
by Chr$
tofro wrote:Chr$ wrote:RalfR wrote:Not possible to make a Fastram (like SQB or Miracle) there? (I do not know, sorry)
I'm a noob of course, but I'm sure that only external RAM can be fast. I suppose there must be other things/signals needed that are only available on the expansion port and it's probably tricky or at least inconvenient to pick them up internally?
Well, "fast" memory (rather "non-contended memory") needs a separate data path between the ULA and memory and CPU and memory. As the QL bus is decoupled by the 2 multiplexers, and your memory sits "outside" of the decoupled area, (on the CPU socket), it should actually be "fast" (depending how "DTACK" is generated).
Most internal "slow" expansions were actually piggy-packed onto the internal RAM chips and thus lived in the "shared" access area between CPU and ULA.
Thanks tofro, that makes sense.
Re: DIY RAM EXPANSION
Posted: Thu Jul 28, 2022 7:43 pm
by RalfR
Well... it was clear...as usual.
Re: DIY RAM EXPANSION
Posted: Thu Jul 28, 2022 8:01 pm
by bwinkel67
Chr$ wrote:
I can sell some boards for £1 plus postage. I will probably make up a few for eBay - they take a little time to make due mainly to the fiddly aspect of having to extract the turned pins and place them individually.
That's a nice looking board. I'll definitely grab one of the made-up ones from you (directly to save you eBay fees).
Re: DIY RAM EXPANSION
Posted: Thu Aug 04, 2022 4:32 pm
by Chr$
I have a spare one already made up, in fact it's been made up for a week but then I had to disappear and live downstairs for that time due to getting Covid from a git on the plane from London to Dresden who was sat next to me coughing and spluttering for the duration of the flight. I hoped he had an allergy, but no, 2 days later I had a bad throat and was positive for Covid.
Re: DIY RAM EXPANSION
Posted: Sat Aug 13, 2022 3:23 pm
by Derek_Stewart
Hi Chr$,
I saw you advert on Ebay the board looks really good.
Maybe you coumd integrate the 8301 replacement on the same board...
Re: DIY RAM EXPANSION
Posted: Sat Aug 13, 2022 5:14 pm
by Chr$
Derek_Stewart wrote:Hi Chr$,
I saw you advert on Ebay the board looks really good.
Maybe you coumd integrate the 8301 replacement on the same board...
That might be beyond my ability, but yes, I think something along those lines will be called for in the future, certainly when most of the original 8301's have failed.