21MX proms (per request

[Brent Hilpert]

On 2015-Sep-08, at 2:39 PM, Jay West wrote:
> Sean wrote....
> ------
> 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. 
> ------
> Nope. There is a very good reason why they still command such a price. Worth every penny.
> 
> I can't belittle a 30 year old piece of test equipment no more than I could a similarly aged computer :)

Alternatively, for the rare instance of need, burning fusible PROMs generally or often isn't very complex.

When I needed to burn a replacement 74S387 (256*4) for a repair awhile ago, I hacked up a programmer on a breadboard, controlled by a program running on an RPi. The hardware was an LM317, 7805, 3 TTL ICs, 5 transistors, and a few R/C/D. Add 4 more transistors for 8-bits.