Re: 1541 RAM tester?

Hi Ruud,

On Tue, Jan 16, 2018 at 1:10 PM, Baltissen, GJPAA (Ruud)
<ruud.baltissen@apg.nl> wrote:
> Hallo Frank,
>
>
>> is there any utility that checks 1541's internal SRAM?
>
> To be able to check the RAM using a C64 a certain part of it _HAS_ to be OK anyway. IMHO the best option is to create a ROM that only focuses on testing the RAM. And like the original ROM does, use the LED to tell you things are OK or  bad.
>

yes, this is a good suggestion, the case isn't desperate enough
though. The drive behaves correctly on almost all the situations I
could test,
I've upgraded it to the 1541-II firmware revision and checked
alignment and spindle speed.
On rare occasions, but quite reproducible, it seems it fails reading
or executing correctly (since reads happen via a fastloader routine
uploaded to the drive). VIAs and 6502 have been tested and they're
good. The disks are good enough to work on another two drives.
Might be there're some RAM locations that are never used by the
internal firmware and are failing, though that would be a very strange
failure mode for a SRAM (it happened some times, but it's too rare to be true).

> Notes:
> - I only hope you don't have to desolder the original ROM.
> - Use this ROM to test other things as well, like the 6522s.
>
>
> Met vriendelijke groet / With kind regards, Ruud Baltissen
> www.Baltissen.org
>
>
>
>
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