SIMM 32 MB :-(

From: Petr Stehlik <>
Date: Wed, 25 Feb 1998 09:28:33 +0100

Hi All,

you surely remember me asking if 32 MB EDO SIMM will work in AB40. Since I
got six positive responses, I went and bought the SIMM. I installed it and
turned on my computer. Doug's TK 5.07 found both SIMMs, performed mem test
and announced 48 MB of FastRAM to the TOS.

So I started TTRAMTST 1.2, just to be sure. Soon it found an error - it
wrote $ff but read $fb from about 100 addresses (with 4 bytes offset at
about $28b8xxx). I couldn't believe it so I tried Speichertest 1.0 and
later also RAM.XFS and TreeCheck. Still there were the errors!

Interesting is that Linux bootstrap finds 48 MB in bank 1! That's strange,
since banks are 32 MB max.

So I tried to exchange the two SIMMs, so 16 MB was in bank 1 and 32 MB in
bank 2. Results under TOS were the same. However Linux bootstrap found 16
MB in bank 1 but only 28 MB in bank 2!!

So I guess that:

1) my AB40 is broken and can't handle 32 MB SIMMs properly - instead it
mirrors last 1/4 somewhere else, or the last 1/4 loses data


2) the SIMM is broken and loses data

What do you think? Can anybody come with an advice?

BTW, I don't understand the SIMM - it's doublesided (16 chips), no
manufacturer (just some strange logo with circle and square). The chips are
V53C17405AK50. What's that - 50 ns? I doubt it.

As for my AB40 - there are JP1, JP2, but they're free. Do you think a
jumper could help me?

Anyway, I'm tired and sad it doesn't work.

E-mail:                        PARCP developer
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mirror:                 Atari 800XL emulation
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Received on on. feb. 25 1998 - 10:19:00 CET

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