From: William Levak (wlevak_at_grex.cyberspace.org)
Date: 2006-05-29 06:42:57
On Sat, 13 May 2006, Spiro Trikaliotis wrote:
> I think, I found the true originating source to Garth Wilson's
> explanations. It is the 6522 datasheet from Synertek, who knew
> in 1982 (!!!) from _several_ 6522 shift register bugs and
> corrected one of them. Unfortunately they did not correct _the_
> bug.
>
>
> Read more in:
> http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
>
> page 7 (8 in the PDF), section 5.1, "Shift Register Warnings".
>
> Wow, it _only_ needed 20 years to find out, why _really_ the
> 1540/41 disk drive is/was so damn slow ;-) Commodore really had
> some bad luck with the 1540 design. They could have easily fixed
> the bug, if they knew Synerteks datasheet <sigh>.
This is dated March, 1982. I assume Synertek 6522 chips after that date
are OK.
I have a 1984 Rockwell data book. They do not mention anything about
this, so I assume they never fixed the problem.
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