GVP A500 HD8+ question

GVP A500 HD8+ question

Post by Curtis McC » Fri, 13 Apr 2007 07:01:30

I just picked up one of these for my A500 and it works fine.

I also picked up 4 X 4Mb SIMMs to install, but I have some questions.

I did manage to easter-egg a jumper setting to get 8Mb recognized (J5 &
J9, J12-1 & 2). This wasn't shown in BBOAH. Dumb luck, I guess!

I do seem to remember there being a limit of 8Mb RAM on the A500.

If that is true, is there anyway of getting around that?

So, if I can use the extra memory, what are the jumper settings? Or
should I start easter-egging again?

Anyone know where I can download a copy of the manual? I've got the
software that came with it.

I'm using an A500 with rev. 5 mobo and WB 1.3.


GVP A500 HD8+ question

Post by Clockmeist » Fri, 13 Apr 2007 19:45:19

True. Well, 9mb including 1mb chipRAM.


I found the jumper settings by Googling.


GVP A500 HD8+ question

Post by Clockmeist » Fri, 13 Apr 2007 19:47:46

Less then 20 seconds found this...


GVP A500 HD8+ question

Post by Curtis McC » Fri, 13 Apr 2007 23:34:15

THAT is directly from Big Book of Amiga Hardware and is silkscreened on
the unit! Doesn't work for 4Mb SIMMS, at least not mine.

So, it seems you're saying the only way around the 9Mb RAM limitation is
to use an accelerator?

GVP A500 HD8+ question

Post by Clockmeist » Sat, 14 Apr 2007 03:44:55

Yep. It's not called a HD8 for nothing either ;-)

9Mb is still quite a bit of RAM for an Amiga of that era with a stock 68000.

GVP A500 HD8+ question

Post by Curtis McC » Sat, 14 Apr 2007 06:33:28

Good point. Guess I'll force myself to be happy with 9 Mb. Still wish
I could've used those other 2 4 Mb SIMMs. Seems a bit of a waste to
have those 2 slots empty!

Another question. I noticed there are only 4 RAM chips on the
motherboard. Also saw somewhere a hack to add 4 more chips in the
sockets between the chips for more chip RAM. If I were to upgrade to
the Fat Agnus chip and add the RAM chips to the motherboard, would I be
able to access the additional chip RAM and still have 8 Mb of fast RAM?
Or did I get the chip and fast RAM references bass-ackwards? In a
sense, wouldn't that give me a total of 10 Mb of RAM? Not a whole lot
more, but still a bit more boost.

GVP A500 HD8+ question

Post by zippe » Sat, 14 Apr 2007 23:19:41

To get 2 MB Chip you need a Megachip2 addon board or something similar.

GVP A500 HD8+ question

Post by Clockmeist » Sun, 15 Apr 2007 05:41:10

"Curtis McCain" < XXXX@XXXXX.COM > wrote in message
news:fAxTh.79524$ XXXX@XXXXX.COM ...

Yes, you get an additional 512kb fast or chipRAM that would otherwise occupy
the trapdoor RAM slot assuming you install a 1Mb Agnus as well.

If I were to upgrade to

Up to 1Mb of chipRAM, you can't have 2Mb chipRAM on a stock A500 unless you
use a Megachip or similar that can address 2Mb chipRAM..

It would give you 1Mb chipRAM/8Mb fast or 512KB chipRAM/8.5Mb fast depending
on jumper setting on the motherboard.
Using the additional chips means you can't use the trapdoor memory as
chipRAM because it occupies the same logical address space as the additional
onboard chips.

With a Megachip it is possible that you may get 10Mb total memory (2Mb
chip/8Mb fast) depending on what physical address space the Megachip memory
occupies and if there is overlap with the HD8+ there may be problems.