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From: Robert on 4 May 2008 13:50
In article <67t568F2qmjicU1(a)mid.individual.net>, welte_spam(a)freenet.de
says...
> Hi Robert,
>
> Robert wrote:
> > I finally got round to replacing the fuse holder in the chicklet-key PET
> > 2001 I was given about ten years ago.
> > And lo and behold it came up right away showing a massive amount of 512
> > BYTES of free memory.
>
> 512 bytes isn't much. Also it's in the middle of a RAM chip, so I don't
> think your problem is a contact or solder problem, or broken other logic.
>
> In the old static memory 2001 PET with 6550 or 2114 type SRAM (which one do
> you have) memory is organized as 8 pairs of 4bit chips, each pair
> incrementing memory by exactly 1kB or 1024 bytes. As the BASIC memory
> starts at address $401 or 1025, the displayed bytes free is always 1 byte
> less than the full amount of memory installed. The first kilobyte is never
> counted, it is used by the system. So you can have 1023, 2047, up to 7167
> bytes free as valid bytes free displayed.
>
> If your memory is socketed, try to swap some chips. As in your case, the
> second chip pair seems to be bad, swap the second row from the right with
> the second row from the left and see if it makes a difference.
>
> The problem is, the second bank in 2114 computers is on the left side, but
> in 6550 computers it's on the right side. Or vice versa, I forgot :) But
> swapping them this way, you can't make a mistake :)
>
> If you have a 6550 machine and find some broken chips, have a look at my
> site www.x1541.de! You can find some instructions and hardware there to
> replace them with better components.
>
> > The same machine has the plastic bars that allow the keyboard to be
> > screwed against the metal case broken in the areas where the screw holes
> > used to be. What material can be used to fix this (some resin/epoxy
> > maybe??)
>
> Maybe. I think I would glue a whole strip of fresh plastic on top of the
> broken part, so the force from the screws won't break the repaired areas
> again. Just use longer screws then :)
>
> Nicolas
>
Thanks for the input, everybody across this thread. I'll try and tackle
this when I get home at the end of the week.

I'll need to find some 2114 memory chips, as I don't want to go into a
swap routine that might damage my mainboard, as the chips are not
socketed.

Front row is labelled J, No. 1-8 from left to right, second row is I.

Robert
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