add 1 MB onboard ram to A500 Revision 6A MB

[klx300r]

EXCELLENT :-D  Just finished the mod and it worked great !!! got a bit of a scare when I first booted it up & got greeted by a green screen but I troubleshooted the problem as being some extra flux on the board sooo after a good cleaning all was fine and peace was restored back in my Amiga land :lol:

thanks very much for your help :pint:

Woaaa... what is this thread exactly about?

Did you want MORE than 1MB chipRAM or did you simply want to add 512k onboard and go from a 512k total ram Amiga 500 to one with 1MB chip?

I have an Amiga 500 here with 512k and the same MoBo revision. I also have piles of 256kx4 DRAM chips that are exactly the same type and I was asking myself exactly what I should do to expand the 500 to 1MB and make sure its all chip ram.

BTW, the Agnus chip in there is 8372A which does support 1MB chip.

If it really does require special logic chips to do that then it really sucks. The A2000 can go from 512k chip to 1MB chip just by flipping 2 jumpers and having the right Agnus and this board even has all the sockets...

[TjLaZer]

I also have a rev 6a A500 with 1MB chip soldered on the board. How can I add some fast mem to the expansion slot? An A500+ mem expansion card maybe???

[Zac67]

A500+ cards only fit an A500+.
You'll need a sidecar expansion or something that goes to the CPU socket for real fast RAM.

[Chain]

klx300r wrote:

Chain wrote:
http://eab.abime.net/showthread.php?t=31816

followed this thread and I'm more confused now then when I started out :-?  so did you ever get this mod to work to get 1MB chip soldered on board, 512k fast with RTC working fine on trap door on the Rev6A motherboard :-?

im also confused, dont worry

im posting updates to eab
cant maintain two threads sorry

[Chain]

TjLaZer wrote:
I also have a rev 6a A500 with 1MB chip soldered on the board. How can I add some fast mem to the expansion slot? An A500+ mem expansion card maybe???

 you need those three chips inbetweeen RAS lines

[klx300r]

eslapion wrote:
Woaaa... what is this thread exactly about?

Did you want MORE than 1MB chipRAM or did you simply want to add 512k onboard and go from a 512k total ram Amiga 500 to one with 1MB chip?

I have an Amiga 500 here with 512k and the same MoBo revision. I also have piles of 256kx4 DRAM chips that are exactly the same type and I was asking myself exactly what I should do to expand the 500 to 1MB and make sure its all chip ram.

BTW, the Agnus chip in there is 8372A which does support 1MB chip.

eslapion! dude yur everywhere man :-D  anyhow to make a very long story short YES you are able to get 1 mb chip ram with a 8372A agnus by basically cutting 2 jumpers and soldering 1 i.e see JP7a and JP2 & see link above...this mod allocates the trapdoor 512 k to chip memory rather than fast...