Problem with HP25C.
Calculating is o.k. Prgramming not o.k.
I can try to programm the HP25C.
Every step, done by sst, in programming gives the following:
step #1 f prgm 00
step #2 01 13 00
step #3 02 13 00
...
step # 49 13 00
It does not matter what keystrokes I give.
Who has the solution for this problem ????
You RAM chip is bad. Only source is another machine. You may be able to use a RAM chip from a 29C. Also some 25C machines use two RAM chips. You have to add a resistor to use a single chip device in a two chip machine.
I have found 6 Chips ( IC ) in my HP 25C.
Is there someone who can sum up the functionality of every independent chip ?? Where can I find that kind of information ??
The smaller chip under the display module is the ROM0/anode driver chip. The larger one is the cathode driver. The big, wide chip at the bottom of the circuit board is the ACT chip (the CPU). The one to the left of it is a ROM chip. The other two (the ones above and to the right of the ACT) are RAM chips.