21MX proms (per request

Jay West jwest at classiccmp.org
Wed Sep 9 18:46:37 CDT 2015

Sean wrote...
 my bench is all Racal, Tek, HP, Fluke, etc and the 
You must be one of those high net worth folks you mentioned in your previous post, I'm jealous of that kind of bench gear!

I'm not saying the CP-1128 isn't a great value. Of course it's a good solution! I am merely saying the Data I/O 29B currently and has been a good value (in response to your post saying it was "too expensive for 30+ year old gear"). But since it was brought up, here's some things to consider....

The Data I/O 29B is specifically sought out by arcade enthusiasts (and many vintage computer collectors that I know) because it supports an unusually wide array of vintage chips, most that we're likely to come across. Why is that important, if the CP-1128 does - as glen points out - program a subset of the needed (for this specific case) chips?

Answer from past experience.... There may be a dozen chips that will work for the HP 1K loader roms. What I have found over the past many years is that the supply ebbs and flows. Good example - for about a year, MMI 6301's were unobtainium. All the suppliers I could find were all pushing the Harris 7611's, because they couldn't get the 6301's either. Then a year later, apparently a batch of fuji 7114's were found and those were available, because suppliers couldn't find any more 7611's (at the time). Now I'm finding the MMI 6301's again. Yes, these chips are all compatible once programmed, but some programmers will do one and not the other. This "ebb and flow" in supply may occur right at the least convenient time, like when your 2000/Access IOP firmware chips die (me, about two months ago). If your programmer supports the widest possible selection of chips, even post-programmed compatibles, you're in a better spot. If not, a post-programmed compatible chip may well be available, but your programmer doesn't support it. Not a great spot.

My 29B will also do a lot more different types of devices than usual, thanks to the plethora of other adapters (not just unipak 2B) that came with mine. 

Another good example - the CP-1128 appears to require a usb attached computer to function. While I usually connect my 29B to a computer to program (via serial), there are a few occasions when I've been exceedingly glad that it can be fully operated from the built in control panel without having to have a computer to run it.

Another example - Some manufacturers, over time, drop support for very early devices. That can't happen with the 29B ;) It sure can and does happen with current devices being manufactured.

There's a downside of course... just try finding replacement parts for a 29b ;) Fortunately, schematics exist.

Long story short, as I said before, there's a reason that programmer still holds a high value. For some people, those reasons are worth it. For others, they are not. Is the 29B "the best" programmer? Probably not, as "best" is both situational and subjective. I'm willing to allocate portions of my precious small bench gear budget for the above reasons. But several folks asked at the same time for advice on 21MX M/E/F proms and programmers, and that post was my advice. There are certainly other great programmers out there.



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