Maximum RAM in an A500

[Cyberus]

I was just wondering what actually limits the RAM in an A500. I recently picked up a Midget Racer accelerator for my trusty old (almost 14 years!) A500, and it has an 8MB add on card, but what's to stop me populating my GVP Impact II card with even more RAM? I see everywhere that it can have a maximum of 9MB, but why? Is it just that this is all that was envisaged as being possible at the time?

Cheers

[zipper]

On my towerized+zorroed A500 with Blizzard 2060:
128 MB on Blizzard, max 8 MB on Oktagon 2008 and 2 MB on Megachip2, so total max of 138 MB.

[Kees]

@ zipper

Thats one loaded a500 !

[zipper]

So the zorroII area takes just max 8 MB. You need an accelerator that uses 32bit area for addressing memory.

[Cyberus]

Whoa, overkill!

But why not buy an A2000, or is it because
a) like me you have a bit of an A500 fetish?
b) A500 mobos are ten a penny?

Cheers

[zipper]

a)
and a shopkeeper who sold me the tower instead of just a Slingshot - and then I just decided to get the best. I was very sorry that Blizzard 2604 PPC board never got to the shelves. :-?  :-?  :-?

[Steady]

@Cyberus

The RAM in an A500 is limited by the fact that the 68000 can only address a maximum of 16 Meg RAM. Once you take away bits that are reserved and used for hardware etc, you are left with 8Meg FAST RAM, 1 MEG CHIP RAM (although 2 megs can be addressed, the custom chips in A500 can only address that much max), and 512k (or 1 meg, can't remember) of RANGER RAM, which is known as the slow RAM. If you add a board with a full 68020 or better, you will be able to have more RAM because they use 32 bit addresses.

[Cyberus]

So with an 030 accelerator, I should in theory be able to add more than 8MB....

[Damion]

So with an 030 accelerator, I should in theory be able to add more than 8MB....

Correct. Most boards should allow at least 64mb
(although the 32 bit '030 can in theory address
far more).

[zipper]

Almost all 030 accelerators map their memory outside ZII area, so 99% yes.

[KnightStalkerBob]

Unfortunately, the GVP A530 only allows 8MB, through a proprietary SIMM layout :-(

[Steady]

Bummer, there's always a catch...

I guess you just need to check each product to be sure before you buy.

[Cyberus]

I'm hoping to combine the RAM on the accelerator - 8MB, with the RAM from the machine and KCS Powerboard - 1MB, with another 4MB I have in GVP 50-pin SIMMS in my 'sidecar' SCSI controller, giving a total of 12 MB...

[ksk]

zipper wrote:
On my towerized+zorroed A500 with Blizzard 2060:
128 MB on Blizzard, max 8 MB on Oktagon 2008 and 2 MB on Megachip2, so total max of 138 MB.

:-o  WOW! :-o

That I would call a Atari520ST killer.  :-P  

[redrumloa]

zipper wrote:
On my towerized+zorroed A500 with Blizzard 2060:
128 MB on Blizzard, max 8 MB on Oktagon 2008 and 2 MB on Megachip2, so total max of 138 MB.

That must be an infintive (sp?) busboard?