
Fatal disk errors on an Amiga 4000 unless the clock app is just so - doener
https://www.theregister.co.uk/2020/04/10/on_call/
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robocat
This answer seems to have some likely leads for the cause:

[https://forums.theregister.co.uk/forum/all/2020/04/10/on_cal...](https://forums.theregister.co.uk/forum/all/2020/04/10/on_call/#c_4012741)

which refers to:
[http://www.jeacle.ie/pub/articles/4008/](http://www.jeacle.ie/pub/articles/4008/)

There were various revisions of Amigas and various different SCSI cards and
software workarounds - without more info little can be concluded.

“models of the A4000 were shipped with a broken Buster chip which prevented
many Zorro-III boards from working correctly.”

“The Fastlane card, on the other hand, was smart. It knew about the broken
Busters and had a work-around to compensate. Performance wouldn't be quite as
good as with a fully functional Buster, but the card would still work well.”

“The problem with old Zorro-II cards [snip] is that the Amiga 4000's 32-bit
RAM is outside of the 24-bit DMA-able address space which these controller
cards can see, so data can't be transferred directly from the SCSI device into
main memory. This means the CPU ends up dealing with requests and individually
copying a few bytes at a time to and from 32-bit memory.“

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Zenst
Interesting problem and one of those quirky solutions that start of as a
temporary fix and yet become ingrained as standard working practice. May even
be few related quirky solutions across systems that all add up to the real
issue and that may very well of been network timing and without digging deeper
and other tests, be hard to eliminate.

Was this unique to this system, could it be plugged into a different network
port and have same issue, could another system have the same issue. Was the
system bios/os levels the same. So many things that without knowing, won't
narrow this down. May even be settings of a dip switch on an HS causing timing
issues and as these early systems did much in software upon the CPU over
dedicated chips and corners saved. System clocks and timing circuits can
become one of those things that spring up with the quickest and most
intermittent and apparently unrelated forms of fun in IT.

Hence the usual process of elimination to narrow it down lacking in this
problem and solution outlined and with that, could be many factors at play,
even a dying capacitor or a bent ribbon cable/poor connection. SO many
possible reasons for it to cause this kinda quirk. But certainly a good
example of one of those mysteries you get and real issues that are fun to
investigate albeit time/pressure to get things working can and often do see
the temporary solution become part of working practice.

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doener
Via
[https://old.reddit.com/r/amiga/comments/fz7qh6/amiga_4000_my...](https://old.reddit.com/r/amiga/comments/fz7qh6/amiga_4000_mystery_in_the_news/)

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renox
And that's why I'll never use an OS without memory protection..

