ACT available

[Dieter]

(01-29-2015 09:24 PM)PANAMATIK Wrote:  I agree very much to your statement. But I don't have the choice to drop the H and P for b and c. The few segment combinations that can be displayed are hard coded in the HP chip on the other side of the printed circuit board!

I admit I do not have the slightest idea how electronics and hardware like this work (I'm more interested in software and algorithms), but even with this zero-knowledge I understand that the best software cannot change what's fixed in hardware. ;-)

(01-29-2015 09:24 PM)PANAMATIK Wrote:  Perhaps I didn't write clearly enough, ...

Well, in this case it's obviously me as the recipient of the message, I assume... #-)

(01-29-2015 09:24 PM)PANAMATIK Wrote:  There are only four electrical serial communication signals between the ACT chip and the display chips, called PHI1, PHI2, ISA and RCD. If you see 000000000000 in the display it is a sign that the ACT is producing the clock signals PHI1,PHI2 and RDC correctly, but the data signal ISA remains 0V. The display driver interprets 4-serial bits at low level as number zero and displays the six segments abcdef, which is number 0 for all digits. Perhaps only the ISA signal line is disconnected or the ACT is defective, I don't know.

If you don't now I don't either. ;-) But...

(01-29-2015 09:24 PM)PANAMATIK Wrote:  Anyway it can be repaired soon by he new ACT for HP-29C which I'm working on.

Great. This could mean a new life for this beauty after four years in the drawer *sniff*.

Dieter