HP-19C Repair Odysee

[PANAMATIK]

(03-08-2021 09:32 AM)teenix Wrote:  Hi all,

I looked into a PIK chip replacement circuit just at an ad-hoc level and just parts including PCB should be around the $15 mark give or take. It is a bit of a hassle because most of the PIK signals are 0-6V and require level shifting to suit a modern processor.

The main thing is getting it going. One problem is the time involved and how this relates to demand which doesn't seem great from what I've seen so justification becomes an issue too.

The other problem is that this is a controller for hardware which is pretty much irreplaceable. There is a real chance of causing damage during development. Burnt print heads, motor drivers, stripped gears or a damaged printer mechanism are examples if the software crashed for some unforeseeable reason at a critical point. This is much more relevant than interfacing to the card reader or display.

Unfortunately, all of the printer hardware is totally reliant on software for correct operation, (assuming the driver circuits are ok) so it is quite a risk to take, a problem which I am still grappling with for the 97 CPU board replacement.

cheers

Tony

The HP-19C printer module is more suited for development than HP-97, because its mechanic cannot get blocked. Also I would take my partially damaged printhead, which has still 2 pixel lines left for developing. I see two different ways to go:

1.) Development of a new HP-19C processor board with integrated keyboard scan and printer pixel output in one chip, could be a PIC processor. This would spare the complicated communication through ISA and DATA line between ACT and PIK. This solution is not suited for HP-97
2.) Replacement of the PIK chip as exact as possible, suitable for HP-19C and HP-97. I assume it would need a FPGA solution for correct timing and it is more difficult to develop (not to mention alle the level shifting problems).

I'm not sure which way to go at the moment.

Bernhard