HP97 The journey begins

[teenix]

Hi all,

I have done about 95% of the Spice code, still waiting on processor chips.

One good thing, I received some processors for the 65 and 67 CPU boards, so they can be made again :-)

I am still working on the ROM replacements and the results so far look ok.

The traces in the top part of the attached image shows the Phi1, Phi2 and SYNC signals, followed by the ROM address which is starting at address 0h. These signals are generated by a simplified ACT processor.

The next trace is the output from the ROM replacement IC which is programmed for the HP-92 ROM 0 chip, 1818-0346.

$0000 0D0 display reset twf
$0001 1AE a + 1 -> a[x]
$0001 1AE a + 1 -> a[x]

The lower scope shot shows a close up of the data stream at address $0001 and how it mimics the real data coming from a HP ROM IC. The instruction in the lowest trace can clearly be seen as $1AE, LSB first - a + 1 -> a[x].

The ROM 0 IC also outputs data to the anode driver and this is taken care of as well - not shown.

I'm expecting next gen circuit board in next few days. The first ones didn't work as expected and led to a lot of head scratching to source appropriate parts.

Fingers crossed.

cheers

Tony