Amiga 500 - 1MB CHIP RAM RESOLVED.
First I checked the fast and chip on an
unexpanded Amiga 500.
With WB loaded I get 0 fast and 312K RAM.
On the A500 with the card I am getting
900+ chip and fast which can't be right.
Something is reporting wrong figures.
2MB combined without a card is bonkers.
And there is no card in the computer.
So I fit the card to the unexpanded 500
And all I got was a yellow screen.
The check wasn't getting past the RAM.
Just to be sure I checked the slot
on the unexpanded Amiga 500.
This gave 440K chip and 395K fast.
A total of 842K so the connector was working.
So what capacity were all these chips
on the A500 with the strange card.
I set up the Black Label A500 and
powered up with no card.
And with no card I am getting 900 fast and chip.
Just to prove there was no card fitted.
I then loaded WB and fired up DOpus.
At around 500K used the computer locked up,
And I am greeted with the GURU.
Each time at around 1.5MB the computer halted.
I tried again with the card fitted this time.
I got exactly the same result. DOpus
got so far and then kicked out.
One issue I was aware of is that with
the switch at the back of the computer
down it locked the floppy drive on and
made it unusable.
It was at this point that I removed the
GARY and discovered a piece of sticky backed
tape on the back that was causing the GARY
to rock. It was neither in left or right
tightly. I even tried removing completely
and just having the GARY and no card. That
did not work.
I then reseated the GARY and it clicked a lot
further into the slot. It even gave out a
very healthy click as it located itself.
And this time I got a green screen.
Then I got a grey screen. Which was a
very good sign to me.
And then it showed the WB requester.
I tried to boot DOpus but failed again.
ONLY ONE THING FOR IT...Put back the
card and see if the reseated GARY works.
INCREDIBLE.. INCREDIBLE. Just 1.4MB free.
That was way more believable.
And DOpus fires up. Even more INCREDIBLE.
And just 828K free. That makes sense.
SLOW RAM Public 500K. CORRECT.
Chip memory 1.0MB and that is correct.
THE COMPUTER IS NOW WORKING PROPERLY.
The expansion card is configured by
the GARY to fool the Amiga into thinking
the RAM on the card is CHIP RAM so the
512K onboard + the 512K on the CARD gives
the combined total of 1MB and only 1MB
as the AGNUS is a 1MB chip.
The filled in slots on the motherboard
give another 512K slow fast as this is
on the same bus, but is not accessed by
AGNUS as CHIP.
Clear as mud.
And if I had read the back of the trapdoor
cover I would have seen that I needed to
have the switch up for it to work. I had
assumed the switch had nothing to do with
the card. But it did.
Interesting that the only chip he didn't
glue down was the one that wasn't seated
properly. The sticky pad was actually
preventing it from sitting correctly. It does
now and best of all the computer is working.
I like happy endings.
