HP97 The journey begins

[teenix]

Hi all,

Having a bit of fun ironing out a few quirks with the Constant Memory 67 CPU board, but it seems fine at the moment. To minimize manual handling of the 67 while testing, it has an external power supply, and I gave it a remote keyboard which operates from PC mouse clicks. It also has an isolated serial interface which means the 67 can be powered up or down with no chance of unwanted external voltages appearing on the circuitry and also allows re-programming. The re-programming cycles can be repetitious during testing so only changes in code are actually reprogrammed instead of the whole chip. All this was a bit fiddly setting up, but in use it saves a lot of time.

I tried a read/write from a card and from internal storage and all good. Turn the power off, turn it back on and all data is still there. I loaded and ran the HP-67 diagnostic cards and it all worked ok. Turn the power off then on and press [A] and it works again.

[f] [P<>S] works as expected even after a power cycle, so I think all memory actions are working. The display also shows the last contents of the C register, and the display is formatted the same as prior to power down.

The 67 Microcode is still original and the new PIC code is still compatible with the earlier CPU board. The Constant Memory will be detected automatically and can be switched on, off or reset as desired from the internal menu system.

Still a few more tests to go, but encouraging :-)

cheers

Tony