Unknown ROM. Monitor 1A


Hello. I have an unmarked HP41 ROM. There is a part number "etched" into the bottom that I don't recognize, "ET-14048". I'm not sure if this is a diagnostic type ROM. I received it with an unmarked Diagnostic ROM. The interesting thing is, a CAT2 shows "Monitor 1A". The label listing is a subset of the HP-IL Development ROM including SCOPE and MONITOR. The items that are mostly missing are the boolean, alpha and non-decimal math. There are 2 other functions included that aren't listed in the Devil ROM, IOFSX? and SETBUFX. If you are familiar with these functions let me know because I'm assuming the others that are common with the Devil ROM function the same.

Has anyone had experience with this ROM or heard of it. My guess is that it was a precursor to the Devil ROM used internally for some IL diagnostic. Or, I may be dreaming too much and it is simply an unlabeled standard ROM of some sort. Was there a "Control" ROM ever made?

Thanks for the help!


There is a ROM made to use with the 3421A data acquisition/control unit. Its part number is 44468A. It doesn't have any of the functions you named. Its Cat2 description is -INST 1A-.


It is an 'early' version of the DevIL ROM, one that wasn't generally sold to customers. And yes, most of the functions are the same in the DevIL ROM.
SETBUFX is the same as BSIZEX, and I think the other function you mention has an equivalent too. I believe that the diagnostic programs for HPIL devices were type-in programs for the HP41 using this module, and that if you
translate a couple of functions (SETBUFX -> BSIZEX is the main one) then they'll run on a normal 41 with a standard DevIL ROM.
I believe, also, that the MONITOR 1A rom was released to PPC and distributed by them as PPC EPROM 5A (that's just the name on the hip -- the title that shows up in CAT 2 was MONITOR 1A). Or at least that's what my synthetic quickref implies


Thank you for the information. I'm aware of the Data Acq ROM and hoping to obtain one someday.

Are the HP-IL Diag programs you mentioned Tony in the HP41 Service Manual are somewhere else.

Thanks again for the insight.

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