Datron 1271 firmware bug

[Mickle T.]

I have an old Datron 1271 DMM in excellent condition. But one day I found a strange bug in the DMM's firmware: the full scale (display range) is limited to 199 990 000, but not the standard 199 999 999. DMM is 1992 year of manufacture and have no any sign of repair. Full selftest is passed. S/W ISS 02.10.
Can anyone help with a more fresh ROM dump?

[TiN]

Ain't firmwares from 1271 and 1281 compatible? I'd try flashing 1281 just to see if that's true.

[Mickle T.]

They are totally incompatible 

[dacman]

The Fluke 8508A does the same thing.  It's in the specifications (although not in the extended specifications).  I would assume it is not really a bug on the 1271.

[Mickle T.]

Well, it's time to dig in the 1271 f/w code 

[dacman]

Datron may have done that so that it does not need to check how many digits are selected for display.

[quarks]

unfortunately I missed this, but I think it is as designed and not a bug.
I can check my 1271 and 8508, when I am back in my lab.

edit: as expected both (1271 and 8508) show the same 199.990.000 digits and then switch the range
       exactly what is in the 8508A user manual (see att. screenshot)
       and makes perfect sense for 5digit resolution