Re: Looking for a Micro SCI disk controller

[mjmahon@aol.com (Michael J. Mahon)]

Eric Smith wrote:

<lucid explanation (that I hadn't seen when I posted) snipped>

>Back in 1980 I programmed a double-size PROM (512x8) with the contents
>of both the P5 and P5A PROMs, and wired the extra address line to a
>switch on the side of my Apple ][+.  IIRC, the PROM was a Texas
>Instruments TBP28S42, though the 82S147, 6349, 7649, 74S472, or 74LS472
>should also work.  I had to write a little program to reformat the data
>because of the way the address lines are arranged on the larger chip.

There was a company that offered this mod as a product, too.

(You reminded me how Woz permuted the address (and data?) lines
to save some vias.  He really knew how to exploit "don't cares"!  ;-)

-michael

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