Dynamic Engineering Portable PDS RAM Card

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campbellashe

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Sep 8, 2025
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trag

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Oct 25, 2021
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campbellashe said:
This is the next gen board:

github.com

GitHub - 2tf2294x4g-maker/MacintoshPortable8MB_RAM: Mac Portable Variable 4 or 8MB RAM expansion card — all-5V, AS6C8008 SRAM, ATF1502ASL CPLD. Expands to 9MB total (system max).

Mac Portable Variable 4 or 8MB RAM expansion card — all-5V, AS6C8008 SRAM, ATF1502ASL CPLD. Expands to 9MB total (system max). - 2tf2294x4g-maker/MacintoshPortable8MB_RAM
github.com github.com
Click to expand...

I have not been following in detail. Have you looked at addressing/solving the loss of performance when the address strobe signal is used for RAM greater than 5 MB (4 MB?)? Apologies if I'm mistaken about that. I think I saw it in one of @JDW 's videos.
 
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campbellashe

New Tinkerer
Sep 8, 2025
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Asheville, NC
I don't have an elegant way yet.... I was thinking of jumping on the software side of things with the previously proposed use of an INIT to create a sleep hook to poke $FC0200 on wake. My understanding is just with wake from sleep this occurs? and is related to the logic board side...

My goals was to validate the board and then see if I could work on the INIT once I get it working.

This is the idea: @David Cook

I'm not sure if others have played with the software side to fix this problem.
 
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trag

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Oct 25, 2021
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campbellashe said:
I don't have an elegant way yet.... I was thinking of jumping on the software side of things with the previously proposed use of an INIT to create a sleep hook to poke $FC0200 on wake. My understanding is just with wake from sleep this occurs? and is related to the logic board side...

My goals was to validate the board and then see if I could work on the INIT once I get it working.

This is the idea: @David Cook

I'm not sure if others have played with the software side to fix this problem.
Click to expand...
Thank you. I don't know the cause of the issue. Hearing that it existed was the extent of my knowledge. I appreciate the extra detail you provided.
 
David Cook

David Cook

Active Tinkerer
Jul 20, 2023
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campbellashe said:
I don't have an elegant way yet.... I was thinking of jumping on the software side of things with the previously proposed use of an INIT to create a sleep hook to poke $FC0200 on wake. My understanding is just with wake from sleep this occurs? and is related to the logic board side...

My goals was to validate the board and then see if I could work on the INIT once I get it working.

This is the idea: @David Cook

I'm not sure if others have played with the software side to fix this problem.
Click to expand...

I added that to an unreleased version of my Quiet Portable init. JDW tested it and said it made no difference. If you build a spare memory board for me (which I will pay for), I'd be happy to experiment further with getting it working.
 
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campbellashe

New Tinkerer
Sep 8, 2025
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Asheville, NC
David,

I've got my 8 MB card working. Seeing slow down a boot with the 8MB setup. Do you understand the reason for the slow down. I 'm writing an INIT to poke the GLU; but I was expecting the slow down only to be post sleep; but now realize is is always there and am concerned that the INIT would not have any benefit?
 
David Cook

David Cook

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Jul 20, 2023
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campbellashe said:
Seeing slow down a boot with the 8MB setup
Click to expand...

@SuperSVGA is the expert on this. He stated "Any access at all is sufficient, such as a simple tst.w $FC0200 instruction or running DM FC0200 from the debugger."

Can you try using Macsbug and testing the DM FC0200 instruction to see if that speeds up your card?

- David
 
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