add 1 MB onboard ram to A500 Revision 6A MB

[klx300r]

I had an old mod article that basically said you just had to add 4 more 256 dram chips to the board but I'm not sure if I have to modify any jumpers/ cut traces etc? also I understand that this onboard ram will interfere with the additional 512K on the trapdoor A501 and possible the clock??

anyone done this mod or knows where I can find some info on it?? I found the dram chips and hope to get the ol soldering iron going again soon
 ;-)

[Chain]

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

[Tenacious]

There is a hack floating around (I can't find it yet) to replace your 1 Meg Agnus with a 2 Meg Super Agnus (the one used in the A3000).  IIRC, the 4 existing ram chips are pulled and 8 new 1Meg chips are installed.  With just a few trace mods you get 2 Megs of chip on the motherboard.  You must then disable the memory on the A501 but you can still use the clock.  I did this modification almost 15 years ago and that machine is still running strong.

BTW: I thought I saw 2 meg Agnus for sell on AmigaKit.

If you have 1 Meg of chip (512K on the mb and 512K on the A501), whats the advantage of moving it all to the mb?  You still need the RTC.  If you add another 512K (1.5 meg total) with some kind of glue logic, that 512K wont be true chip nor true fast memory.

You probably know this, but Supra's 500 RX fast ram expansion is one of the best first moves you can make (if you're not going for a HD/ram combo).   I wish I had had one of these back in 1989!

[Jeff]

This hack was in Amazing Computing Amiga magazine in '93 I think. I did it to my rev 6a A500 at the time and it worked great! I still have the article somewhere, but I bet the 1Megx4 drams are hard to find these days:-)

It would probably be better to find a used Megachip.

Jeff

[Tenacious]

I think I remember getting the plans from a magazine as well.  I did find a file on my HD that details a similar hack for the A2000. The URL was still in the file note.   I never tried this one since acquiring A2000s only a few years ago.

I didn't test this link: http://main.aminet.net/hard/hack/A2K_agnus_hack.lha

[AeroMan]

klx300r wrote:
I had an old mod article that basically said you just had to add 4 more 256 dram chips to the board but I'm not sure if I have to modify any jumpers/ cut traces etc? also I understand that this onboard ram will interfere with the additional 512K on the trapdoor A501 and possible the clock??

anyone done this mod or knows where I can find some info on it?? I found the dram chips and hope to get the ol soldering iron going again soon
 ;-)

I´ve did this to a friend´s A500 a long time ago. As far as I remember, there is a jumper to set, and nothing more than this. I´ll try to find the magazine that had this article.

[rkauer]

http://www.savel.org/old/amiga/upgrade.html ...

[klx300r]

hey thanks im gonna try this out & keep my fingers crossed ;-)

[klx300r]

ok please let me know when/if you find that old article as my soldering hand is getting itchy :-)

[klx300r]

thanks for the reply but the link is dead :-?

[klx300r]

Tenacious wrote:

If you have 1 Meg of chip (512K on the mb and 512K on the A501), whats the advantage of moving it all to the mb?  You still need the RTC.  If you add another 512K (1.5 meg total) with some kind of glue logic, that 512K wont be true chip nor true fast memory.

You probably know this, but Supra's 500 RX fast ram expansion is one of the best first moves you can make (if you're not going for a HD/ram combo).   I wish I had had one of these back in 1989!

I basically need the extra chip ram to help my create my own music samples and also when using sequencer and tracker programs...and of course a few games require at least 1 mb chip too ;-)  I already got a Supra 500 RX with 2MB fast ram installed along with a A590 with 2MB as welland a 2GB scsi drive....serves me just fine for my retro gaming and making music :-D

[klx300r]

Tenacious wrote:
I think I remember getting the plans from a magazine as well.  I did find a file on my HD that details a similar hack for the A2000. The URL was still in the file note.   I never tried this one since acquiring A2000s only a few years ago.

I didn't test this link: http://main.aminet.net/hard/hack/A2K_agnus_hack.lha

thanks for the reply but the link is dead :-?

[klx300r]

rkauer wrote:
http://www.savel.org/old/amiga/upgrade.html ...

 hey thanks im gonna try this out & keep my fingers crossed

[Tenacious]

It would be interesting if rkauer's link will convert a NTSC A500 into a defacto A500+ (I came away from the link a little in doubt).  If it works, (and you have 2-Meg Agnus) then all you need is a European (1 meg) A501 mapped to the chip memory address space.

The mod I mentioned above puts all 2 megs on the motherboard, the A501 is retained for the RTC only and its memory is disabled.

The Aminet links are broken because the directory structure was consolidated.  The hardware hacks were moved under the docs.  aminet.net/docs/hard/A2K_agnus_hack.lha

Good Luck

[Tenacious]

@klx300r

You have 1 Meg of chip ram, right? Not 512K of chip and 512k of fast when the sidecars are all pulled off, right?