help - 11/34 console problem - first measurement results
ajp166 at bellatlantic.net
Mon Nov 7 06:31:30 CST 2005
>Subject: RE: help - 11/34 console problem - first measurement results
> From: "Gooijen, Henk" <henk.gooijen at oce.com>
> Date: Sun, 06 Nov 2005 18:06:41 +0100
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
> Cc: "Gooijen, Henk" <henk.gooijen at oce.com>
>> I'd consider that the 8008 is getting bad input data from a bad scan line=
>> which it will output or that it's outputing correctly and the data is
>> corrupted after output due to bad latch or other hardware.
>> One likely possibility is not ram as a prblem but a I/O port that has a
>> stuck bit. Or the control for that port is stuck. This is most likely
>> if the basic fuctions are there (8008 program runs) but some parts of
>> the data used to control the 11/34 or display it's status is not correct.=
>> FYI the 8008 can be single stepped if you pull the "READY" line each
>> cycle and just look at the bus with a simple logic probe or clip.
>Thanks for the good input Allison!
>I hooked a logic analyzer to the address lines A0-A7 on one of the program
>ROMs, and simply sampled the data without any trigger. With the display in
>octal mode, I can see the executed address sequence. The 8008 executes the
>main loop and calls SHFT1 *and* returns to the correct PC. That means that
>the ROM, RAM (to store the return address) and associated circuits must be =
Ok rom for sure and may be on the ram. The 8008 has an internal push
down stack that is 8 deep for call/return.
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