Re: 2445A calibration

Chuck Harris

Harvey White wrote:
The state of LA disassembler probes never reached a point where useful
work could be done, and are in fact a tantalizing way of wasting money.
It seems like it should be possible, was sold as the software engineers
panacea, but it never is.
There are some situations where the LA can be of use, but mostly for
tracking specific events under specific conditions, IMHO.
Indeed, but I find that the LA disassemblers are problematic. It is difficult
to tell with a piplined processor whether the memory reads you are processing
are reading data, or reading instructions. Without a probe specific to the
processor that can make those determinations, you are just looking at
data translated to assembler mnemonics... not useful. The 8086 was the first
commonly used microprocessor to suffer this problem... and solution. Intel
included extra pads that brought out pipeline tracking information for emulators
and logic analyzers.

Tracking specific events under specific conditions is where a LA shines.

The largest problem is that the disassembler probes for given microprocessors
always lags the deployment of those microprocessors, and the fast evolution of
new processors means that the art is always running away from your investment
in probes.
Now for the 6800 and such, you could find the most up-to-date probe,
so that becomes less of a factor for that generation of processors,
I'd think.
Possibly, most of the older processor's pods have been long since scrapped,
but some are certain to still exist.

I just ditched some 6502, Z80, and 8085 emulators... They probably are still
available from the recycler if anyone is interested.

A far better way of understanding an assembly program is to use a
good disassembler, that allows you to use your own labels for data and
jump addresses, and it is generally free. Plus, the software interface to
the hardware processors is surprisingly slow to change, and simple and
cheap to adapt.
Hmmm, got one for the 6800 series? I have core images...
A couple, actually. Sourceforge, and github are littered with them,
particularly the 6809, which is an upfeatured 6802 used in the automotive

PHK, Poul-Henning Kamp wrote a nice one that actually analyzes the code
by executing it. He used it to disassemble the code in some HP counters.


IIRC, the 6802 did more integration of the RAM into the processor. I
think that the DM5010 uses one as well
Tek tended to use the 68B02, which is a 6802 without the internal RAM.

-Chuck Harris

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