Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
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dietert1:
They are offering two categories of equipment, one is alltest_instruments the other one alltest_surplus. If you buy from the first category, you can expect to get an instrument in perfect calibration. In the past i bought from them directly four times and was satisfied. Don't know if that 8506A is a good deal.

Regards, Dieter
SilverSolder:

--- Quote from: joeqsmith on February 20, 2021, 08:00:02 pm ---What's the plan now?  Do you have a goal in mind for the old meter?

I checked eBay and there are a several with what I would consider some very crazy asking prices.   Maybe they are collectibles.   :-DD   

I like this one for about $900.00 with tax and shipping.  "Works",  I know what that means.  :-DD   
https://www.ebay.com/itm/Fluke-8505A-Digital-Multimeter/143819409807?epid=1400599409&hash=item217c4e098f:g:CC4AAOSwuklfoEsj

--- End quote ---

It certainly looks like there aren't currently as many cheap ones available on eBay as there used to be.  Covid?  Getting an instrument of this level of spec for <$100 like you did is a pretty good bargain, if you look at the alternatives...    (there is not much in that category).

I got the GPIB bus up and running again here.  I'm going to have a crack at the high speed reading mode next.  I'm thinking of using it to digitize a swept spectrum analyzer.



joeqsmith:
I was wondering more about trying to make sense of the firmware.   If you wanted to add a feature or fix something. 
SilverSolder:

--- Quote from: joeqsmith on February 20, 2021, 11:59:10 pm ---I was wondering more about trying to make sense of the firmware.   If you wanted to add a feature or fix something.

--- End quote ---

Getting everything on the same version is a huge win, they all behaved slightly differently before which makes it harder to automate calibration, for example.

As long as we can get the high speed reading working, it doesn't really matter what the firmware does any longer...  we will have 100% control from outside.

m k:

--- Quote from: joeqsmith on February 20, 2021, 11:59:10 pm ---I was wondering more about trying to make sense of the firmware.   If you wanted to add a feature or fix something. 

--- End quote ---


i8080 is a notorious hardware partner.

If you check those I/O example sections of manuals of the era you'll get the idea.
Since the processor is really just that it's doings are expensive and bulky pretty fast.
Means that what ever you do is suppose to be a "custom" chip from Intel, so a rich man poor man game benefiting Intel in every corner.

This Fluke is most complicated I've tried to figure out and it has only one of those support chips, that clock maker.
That, I understand, is also a norm among these things, other hardware makers thought they really don't like that benefiting Intel part.

Outcome was what is seen here, shortage of address and data lines made people inventing all kind of custom chip alternatives.
Lack of speed wasn't a good thing eighter, though pipelining got a head start.

Few examples, 0x4000 is start of RAM and 0x8000 is start of hardware I/O where only upper half of address is inuse.


--- Code: ---        ram:0585 21 0f 40        LXI        HL,0x400f
        ram:0588 86              ADD        (HL)
                             LAB_ram_0589                                    XREF[1]:     ram:058a(j) 
        ram:0589 be              CMP        (HL)
        ram:058a c2 89 05        JNZ        LAB_ram_0589
        ram:058d c9              RET

--- End code ---

0x8e ohms converter
0xa2 display numbers
0xaa parallel control out
0xac parallel D7 -> ?

0xa3 display extras and 0xa2/1 enabler
0xa1 display/keyboard address


--- Code: ---        ram:176a e5              PUSH       HL
        ram:176b 26 ae           MVI        H,0xae
                             LAB_ram_176d                                    XREF[1]:     ram:1770(j) 
        ram:176d 7e              MOV        A,(HL)
        ram:176e e6 04           ANI        0x4
        ram:1770 ca 6d 17        JZ         LAB_ram_176d
        ram:1773 26 a7           MVI        H,0xa7
        ram:1775 71              MOV        (HL),C
        ram:1776 e1              POP        HL
        ram:1777 c9              RET

--- End code ---

I've recently wasted time with google.
Everyting seems to be plently first and then finally just junk.
I tried to find an i8080 emulator that would suite for hardware testing but found nothing.
Memory says that Altavista was better.

Obviously I had to start doing my own emulator, it's still just a shell but I'll upload it if it becomes usefull.
For a moment I thought maybe Ghidra addon can do it but then later there will be an avoidable obstacle anyway.
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