A5000 Memory Upgrade

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daveejhitchins
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A5000 Memory Upgrade

Postby daveejhitchins » Wed Sep 27, 2017 11:08 am

Would there be anyone interested in A5000 Memory upgrades to 4MB?

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
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danielj
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Re: A5000 Memory Upgrade

Postby danielj » Wed Sep 27, 2017 11:09 am

Would this be a 4-8MB one?

d.

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daveejhitchins
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Re: A5000 Memory Upgrade

Postby daveejhitchins » Wed Sep 27, 2017 12:36 pm

Sorry, I should have said: 2-4MB

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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danielj
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Re: A5000 Memory Upgrade

Postby danielj » Wed Sep 27, 2017 12:40 pm

*shakes fist at sky* -
Assuming a source of MEMC1As, would a 4-8MB be particularly hard to work out?

d.

RobC
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Re: A5000 Memory Upgrade

Postby RobC » Wed Sep 27, 2017 1:02 pm

danielj wrote:Assuming a source of MEMC1As, would a 4-8MB be particularly hard to work out?

I think the details for the A540s multiple MEMCs are online somewhere. However, I've often struggled to get otherwise functional cards to work together in my A540 and R260.

A better option might be to try to recreate multiple MEMCs + glue logic in an FPGA...

philb
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Re: A5000 Memory Upgrade

Postby philb » Wed Sep 27, 2017 2:09 pm

danielj wrote:*shakes fist at sky* -
Assuming a source of MEMC1As, would a 4-8MB be particularly hard to work out?


As Rob says, I think nowadays you'd be better off reimplementing MEMC1a in an FPGA/CPLD rather than using up scarce stocks of the genuine article. I think the main difficulty with this would be that the A5000 memory expansion connector doesn't expose enough of the address and control signals so you'd have to pick them up from somewhere else, which would mean it wouldn't be a straightforward plugin card. But in terms of the actual electronics I don't think it'd be particularly difficult.

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danielj
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Re: A5000 Memory Upgrade

Postby danielj » Wed Sep 27, 2017 2:21 pm

Didn't the originals pick things up from the MEMC socket?

d.

philb
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Re: A5000 Memory Upgrade

Postby philb » Wed Sep 27, 2017 2:36 pm

danielj wrote:Didn't the originals pick things up from the MEMC socket?


I think so, yeah, but the MEMC isn't socketed as standard on an A5000 so some soldering would be required.

RobC
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Re: A5000 Memory Upgrade

Postby RobC » Wed Sep 27, 2017 3:06 pm

philb wrote:danielj wrote:Didn't the originals pick things up from the MEMC socket?I think so, yeah, but the MEMC isn't socketed as standard on an A5000 so some soldering would be required.

Yes - this is correct. Hence the MEMC being socketed on the Alpha.

I'd love to try to get 16MB on my A5000 - need to find some time and get hold of a 68-pin PLCC adapter!

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daveejhitchins
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Re: A5000 Memory Upgrade

Postby daveejhitchins » Wed Sep 27, 2017 9:54 pm

danielj wrote:*shakes fist at sky* -
Assuming a source of MEMC1As, would a 4-8MB be particularly hard to work out?
Ah! The point here is that no work, other than to find the memory, would be needed e.g. stock of PCBs available!

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com


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