HP-41 question(s)

[Monte Dalrymple]

The 41 service manual mentions a "flag-wired memory module." Does anyone know
what this is?

I know that the Time Module uses input flag 12 and the service request (input flag
13). Is there a list somewhere of what (if anything) uses the other input flags? I
vaguely remember that a couple of the other input flags are used, perhaps by
printers, hp-il or the wand, but I can't find a list anywhere.

Monte

[hth]

(05-01-2018 12:00 AM)Monte Dalrymple Wrote:  The 41 service manual mentions a "flag-wired memory module." Does anyone know
what this is?

I know that the Time Module uses input flag 12 and the service request (input flag
13). Is there a list somewhere of what (if anything) uses the other input flags? I
vaguely remember that a couple of the other input flags are used, perhaps by
printers, hp-il or the wand, but I can't find a list anywhere.

Monte

I do not know how the flag-wired module works, it is supposed to be used by the diagnostic ROM to test I/O lines. It should need some hardware for this. I have not seen any description of it. Unless someone can come up with something, I suppose it may be possible to figure something out by deciphering the diagnostic ROM, but I have never felt inclined to do that...

Looking at my assembler it seems that the printer uses flag 0, card reader flag 1, wand flag 2, 3-5 are unused, 6-10 are used by HP-IL, 11-12 are used by Time. 13 is supposed to be used as a signal that any (other) flag is pulled. I think that hardware may pull its private only flag(s) when selected, but I am not sure that was always the case for early peripherals.

I do not know if there are other peripherals (perhaps non-HP) that uses flags. If one obeys the convention of only pulling flags when peripheral is selected (apart from flag 13), it should be possible to share flags.

Take all it with a small grain of salt.

What are you up to?

Håkan

[Monte Dalrymple]

Ahh... I knew I had seen it somewhere. Thank you Mike and Håkan.

I'm confused about the "clock access failure" one. The Time Module chip
documentation doesn't say anything about this. Is it perhaps generated
by some other module, when the Time Module isn't present?

As far as what I'm working on, it's a new 41C peripheral. ;-)
I don't want to say more until I actually have it working. Right now it
doesn't use the Flag Input, but that may change in the future.

Monte