HP97 The journey begins

[teenix]

Hi all,

Some progress :-)

There is a minor timing issue with the display refresh, but the processor seems to be working and is decoding the ROM code properly.

I'll tweak the display timing and then on to the keyboard decoding next.

Once this is complete, the code I imported from the 67 replacement board should work for the 97 card read/write so I will move on to the printer which involves emulating the original PIK chip, which also has a key press buffer. The new CPU board has hardware to drive the print heads and motor and this will require some effort to get going. The new PIC processor has a lot to do during the print process like character decoding and timing for the print heads, battery voltage monitoring for constant print intensity and motor speed, print head position, braking and direction control etc. All this while still checking key input and running the HP microcode as it is this that controls everything.

cheers

Tony