HP-71 Diagnostics

[KimH]

Thanks Dave

I have contacted the seller as i left feedback, no response yet...

Based on your suggestion I looked at the FRAM Chapter 9.. maybe there will be some inspiration, but it does look like the "Module" has to be in PORT 1...

I was almost sure that it was the OD short on pin 11, which took care of that little detail. That pin is marked HALT in all other ports, including the IL one

I have an "exploded" 71 for experiments (and to Control the World) which I could use to "cut" that OD track on the PCB for one of the ports and determine if:

1) the 71 will turn on at all - i honestly suspect it wont, there will likely not be any D-In to configure where the ROM would reside in the memory stack

2) if it does, then poke around (and share what I find here)

In the BRILLIANT 71B Compendium from Sylvain there is a link to a ROM-dump made by J-F, so one is available. Playing with that will have to wait to next time it rains

The journey continues

(06-06-2020 01:28 PM)Dave Frederickson Wrote:  One feature of the Diag ROM and Port 1 is that they be capable of disabling the system ROM. They do this by shorting the Output Disable signal, OD, to VDD.

This is all discussed in detail in the FRAM71 Manual Chapter 11, Using the SYSRAM feature.

The Diag ROM module has the OD pin shorted to VDD and when plugged into Port 1 it disables the system ROM and allows the Diag ROM to take-over.

If you have any further questions regarding the Diag ROM I suggest you contact the seller as he was on the development team for the 71B and probably knows a thing or two more than we do.

Dave