Classic, Woodstock and Spice Emulators

[PANAMATIK]

(08-03-2016 12:41 PM)PANAMATIK Wrote:  HP-19C Emulator available!

.... I did not yet find the reason, why printing in TRACE mode doesn't show the mnemonics of the last executed function, as described in the manual. Perhaps the microcode of my machine was an early version?

I solved the above problem. There is no doubt any more, that the extracted HP-19C microcode is the original version, it was just interpreting wrong when reading external input pins like the printer mode switch.

After intensively examining the HP-19C hardware and the reconstruction of a full schematic, I discovered that the same signal, which switches between the two upper ROMs, is used also as an input multiplexer for PRGM/RUN switch and the printer mode switch and the printer home switch and motor running input, realized by a tricky transistor circuit. Yes, the single s0 signal has five different functions!

This hardware trick leads to some remarkable consequences: If code in address range 1-6000 to 1-7777 is running, scanning of the PRGM/RUN or printer switch is strictly prohibited, which indeed doesn't occur.

As I understand the circuit better now, I could make some changes and the emulation does work correctly in TRACE mode and shows the mnemonic of the actual calculation . The release of a next HP-19C version will follow in a few days.

If some more experiments will also succeed, I think I can announce that a modified newACT repair kit will finally be available for repairing of defective HP-19C calculators

Bernhard