A500/2000 mikronic chipram expansion help

[alexh]

I am pretty sure that the only thing that 2MB of ChipRAM will let you do is run more WHDload titles while you've got wallpaper in Workbench

(Because you don't run out of chip RAM)

[rkauer]

@DoogUK: Chip RAM is not cache for the CPU. And I don't know any Amiga accelerator who have a cache memory outside the built-in on the CPU.

[DoogUK]

I'm aware of that

[DoogUK]

Ram in any kind of computer does not act as cache for any cpu, but any cpu with a small amount of ram would run exceptionaly better if said amount of ram doubled.

[DoogUK]

the message i got from the seller:

good, let me know whether you are able to fix it.
I tested it with a 8375 2MB Agnus from a A500+, and connected the 2 wires to pin 35-36 (if I remember correctly) of Gary chip.
It didn't work.
Anyway I am 99% sure it needs the 8375 and not the 8372AB, that of A3000, because I have checked all the schematics of both A500, A500+, A2000 and A3000 and took note of all the pin differences among the Agnuses. You can see the cross list on my site, www.oldfab.tk
And, checking the board with tester, all the pins are correct for the 8375 Agnus.

[alexh]

Originally Posted by DoogUK

And, checking the board with tester, all the pins are correct for the 8375 Agnus.

Which one? They differ between A500+ 8375 and A600 8375

[Zetr0]

@alexh

I believe that the 8372AB (common on A3000's) is 2MB pin compatible to the 8375 318xxx series of Agni.

the only black sheep is the A500+ 2MB agnus that has the pin shifts that make it non-pin compatible.

@Doogie

going by what was said, I would be inclined to test the 318xx series Agni you have in it. remember the key facts here... first test it without the gary wires connectd, if it fires up we are on to a winner. if not turn it off FAST!

now connect the signal lines to the gary chip, if you need a socket I might have a 40pin floating around here, you may need to swap wires over if it doenst work the first time.

Originally Posted by alexh

As you can see from my links above, he paid €30 off ebay!


What makes you say that?

well, it's somewhat late, but I have to say that I didn't pay it €30 from ebay.
I had it in a bundle of 4 not working Amiga ram expasions that a friend swapped for some other hardware I had(don't remember what). The 8375 Agnus for the test, I took it from a working A500+. I am pretty sure this is the right Agnus for that board because I did extensive research on Amiga schematic diagrams and a lot of tester measurements and magnifying glass inspection.
regards