21MX proms (per request

Sean Caron scaron at umich.edu
Tue Sep 8 15:19:06 CDT 2015

The median listing price for them on eBay for a 29B with pack seems to be
around $3-400 which IMO is a little steep for a 30+ year old PROM
programmer. Hopefully your best offer successfully accepted was much lower!
I think the part cost on the PROMs pales in comparison. For the cost of the
29B, you could design a replacement for the original PROM, have some boards
fabricated, stuff them and you'd still be ahead a few hundred bucks ...
starts to make sense at those kind of prices, imo.



On Tue, Sep 8, 2015 at 3:14 PM, Marc Verdiell <marc.verdiell at gmail.com>

> >From: dwight <dkelvey at hotmail.com>
> >If I were doing it.
> >First you need to find out if it needs OC output.
> >There are many flash parts in surface mount that can have the higher
> speeds.
> >Add some 74LVC245 to give bus drive needed, also surface mount.
> >All on a little PC board. There would be a lot of wasted space in the
> flash
> but what the heck.
> >Put an edge connector on the board to deal with programming.
> >All will fit in a smaller space than the original part.
> >Dwight
> That would be great engineering fun! But at less than $4 for the blanks,
> using the old PROMs and the vintage programmer seems pretty
> straightforward,
> vintage correct, and low risk solution. Miraculously, my best offer got
> accepted on ebay, so semi-affordable vintage clunky Data I/O 29B Programmer
> and plenty of blanks are being shipped to me :-). I count collecting
> vintage
> tools for servicing your vintage machine as part of the fun too...
> Marc

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