HP-71 Diagnostics

[KimH]

It's raining......

I am one of three who recently got a Diagnostics Module from TAS.

I got it mid week and today I have spent some time going through my stack of 71's.

That was the last ROM-module - made by HP - missing in my little Wooden Tea-Box, I simply had to own it.

One of the interesting parts of the module is not documented well - but has been mentioned here in the past.

When SELECT TEST is flashing after startup, you have the option to pres QQ and you get into something VERY similar to the Debugger LEX for the 82478A.

Many of the functions work exactly as described in the 82478-90001 documentation.

Except:

No Direct Access - Keys 1-9
No Options Stack
No Disassembler

It has been fun to single step through the first several steps starting at #00000 and see how Registers and Return Stack changes, trying to follow.

Because it is hardcoded and hence can't be "configured", it won't work in other ports that #1. I decided to try anyway, just for fun. To no avail... - suspect that the HALT has something to do with that.

BUT

Is that it.....?

Does anyone have a suggestion - or even better, knowledge - as to why this functionality was included in the Diagnostics ROM? It seems to be pointless or at best a curio.

I have seen, but not yet tried, that the image of this ROM can be made to work in the EMU71, that would be next unless someone in this community tells me "Don't bother"

KimH