Upgrade Ram to 1 MB Amiga 500?

[Tenacious]

ECS was simply a the next revision of some of the custom chips (Agnus can address 1 or 2 megs of chip ram instead of 512K, there was a productivity video mode added, etc).

The jumper pad mod mentioned above consolidates the trap door ram into true chip ram memory space (all the custom chips have access to it after the mod).  It's easy to do and worthwile.  Before the mod is done, trapdoor memory is neither  true fast ram nor true chip ram (it doesn't run as fast as the CPU, nor is it usable by the custom chips).

IIRC, some rev 5s shipped with 1 meg Agnus chips.

[Tenacious]

There are several DIY instruction files on Aminet for the mod.  Start there if you want to do this.

I am not aware of any software that chokes on this modification.

[Tenacious]

I'm hard pressed to remember any software specifying ECS chips.  Your machine is probably fine as is for games and early productivity stuff.

I first heard about the consolidated chip ram mod when the A570 came out.  This mod is usually done by ppl who want to push the A500 to it's limits.

[Tenacious]

OTOH, I suppose ECS is used to differentiate software that does not require the more advanced AGA chips.  When said like this, I believe most, if not all, software spec'd for ECS (with or without the mod) would also run on OCS (original chip set).

EDIT: Oops, Fanscale got there first.

[Tenacious]

Also note that the Fat Agnus socket on the A500 and A1500/A2000/A2500 does not have enough physical address lines wired to it to support 2M of Chip, regardless of how much memory is on the Chipmem bus. If you drop a 2M Fat Agnus into this socket, it will work, but it will only ever be able to address 1M.

 =D

This contradicts my memory of a modification I did 15 years ago to my rev 6a A500.   I installed the 2 Meg Agnus (8372B) directly into the socket.  I removed the 4 motherboard ram chips and installed 4 new ram chips.  There is now 2 megs on the motherboard.  The trap door board was retained for RTC only, its memory disabled.

This A500 is still alive and well and obviously my favorite.  IIRC, this mod came to me out of one of the old magazines, but I believe it is now available on Aminet as well.

[Tenacious]

I enjoyed the depth of detail of your ECS timeline.  I only stumbled over the following.

Also note that the Fat Agnus socket on the A500 and A1500/A2000/A2500 does not have enough physical address lines wired to it to support 2M of Chip, regardless of how much memory is on the Chipmem bus. If you drop a 2M Fat Agnus into this socket, it will work, but it will only ever be able to address 1M.

 =D

This contradicts my memory of a modification I did 15 years ago to my rev 6a A500.   I installed the 2 Meg Agnus (8372B) directly into the socket.  I removed the 4 motherboard ram chips and installed 4 new ram chips.  There is now 2 megs on the motherboard.  The trap door board was retained for RTC only, its memory disabled.

This A500 is still alive and well and obviously my favorite.  IIRC, this mod came to me out of one of the old magazines, but I believe it is now available on Aminet as well.

[Tenacious]

@ rkauer

Your signature grabbed my eye.  Is everything OK?