Re: Help with SX64 User Port?

From: smf <*smf_at_null.net*> Date: Wed, 28 Jun 2017 14:42:00 +0100 Message-ID: <545dc6ea-6ceb-bf27-1643-81de064fc086@null.net> · smf_at_null.net

On 28/06/2017 14:16, silverdr@wfmh.org.pl wrote:

> IFIRC everybody thought the 6522 worked correctly so redesigning a 
> well working stuff would be a pure waste of money. Rumour has it that 
> the hardware bug was discovered too late for the redesign.. at least 
> that's more or less what I seem to recall..

The issues with the 6522 appear to have been widely known at the time, 
as was the hardware workround.

The people working on the drive might not have known, or they may have 
thought they could work round it in software.

I don't believe there was a long time between the IEEE interface being 
removed from the 2031 to discovering it wasn't going to work & then the 
decision to bitbang with the CPU, rather than using a 6526 or adding the 
logic gates to prevent the lockup.

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