[time-nuts] Rom Expansion for HP5370B

Bob Bownes bownes at gmail.com
Sun Feb 20 20:52:08 UTC 2011


Start with replacing the existing board with something new.

Step 2, add a USB interface.

Step 3, world domination!

Ok, maybe not so much with the last one...


On Sun, Feb 20, 2011 at 3:21 PM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> In message <AANLkTi=Z8oX4dQWY_nRQDcnkMDHZRRc3QhsaB0=7_gZ+ at mail.gmail.com>, paul
>  swed writes:
>
>>Though only 8K of eprom I suspect its cleverly coded.
>
> It's not really that bad.  There has clearly been somebody there to pound
> structure into the result, and there is very little evidence of code-bumming.
>
>>So its quite speedy and does also have interrupt capability. At a cost of
>>$3-4 each its nothing to use several for different apps like the front panel
>>display and keys, control for actual counting and finally a third for
>>ethernet or GPIB. (Maybe I will get to that one day)
>
> Well, all the existing I/O shares the same 16A8D databus, and there
> is hardly anything gained from having multiple processors fight for
> that bus.
>
> The I/O is also very much built to reduce CPU work, the display/leds
> are self refreshing, the GPIB has its own ROM based state-machine etc.
>
>>But really the key to any of this would be the accurate decoding of the
>>existing software.
>
> I have 303 bytes undecoded right now, 256 of these is a table which
> I suspect is related to floating point squareroots, and a fair
> number of the rest are padding.  As I said it is quite structured.
>
> It is a total no-brainer if you executed it by emulating a
> M6800, and only intercepted a few places to add features.
>
>>Though HP service docs are somewhat useful in this approach for the 5370
>>vintage. At least you tend to be able to understand what IO does what.
>
> The HP5370B is actually very good in that respect, I have been able to
> figure out all the I/O that way.
>
>>For me since the 3 5370s are working, I won't be hacking them anytime soon.
>>Like'em the way they are.
>
> Now, that's the other part:  It is a very good instrument.
>
> The only feature I have been able to dream up yet is a digital
> clock, and only because that is sort of the default for anything
> with a display.
>
> But it could be interesting to see what the hardware can do with
> sufficient CPU resouces, because right now it is clearly CPU-limited.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
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