[time-nuts] Rom Expansion for HP5370B

John Miles jmiles at pop.net
Mon Feb 21 05:11:38 UTC 2011


> I've been looking at this a bit recently.
> Pictures here: http://jks.com

Cool as heck!

> The next step is to move everything to a microcontroller (e.g.
> SAM7X) on a card that replaces the processor board completely.
> As has been mentioned you can do all sorts of crazy, and perhaps
> useful, stuff at this point.

Have you tried going through the various checkout procedures in the manual
to make sure they all still work?  If the 5370 firmware authors *didn't*
bake some timing dependencies into that 6800 code, they were the exception.
Of course, if your emulator is cycle-for-cycle faithful to the 6800 it's all
good.

> I have a question about the dead time of the 5370.
> Can it be eliminated with a fast enough processor, buffering,
> interface, etc. or is it intrinsic to the measurement hardware itself?

Short answer: when fidelity matters, use it in TI mode, not frequency or
period mode.  There will be no dead time in TI mode, and you'll get better
precision as well.  You can still get frequency readings if you want, by
using host software to differentiate the phase values (TimeLab makes this
relatively easy).

I don't know if it would be possible to make zero-dead-time frequency
measurements with firmware mods only.  I doubt it could be done without a
lot of effort that could better be applied elsewhere.

-- john, KE5FX




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