Re: HP 9825 A & HP 9872 B

Paul Berger

On 2020-04-29 10:28 a.m., davidstokes@... wrote:
On Tue, Apr 28, 2020 at 02:58 PM, Craig Ruff wrote:
Do you have another HP-IB peripheral with which to test using the Gen I/O or Extended I/O commands?

Another option might be to acquire a cheap IEEE-488 USB interface and try to drive the plotter directly from a PC to see if it responds to the HP-IB port.
Hello Craig,

Thanks for your swift reply. 

My collection of HP gear is limited to the 9825, 9815 and 9872, so unfortunately I don't have anything else to test the HP-IB 98034.

The vendor now assures me the previous owner used the plotter without anything in that module drawer, so I now plan to lift the platen, and activate the 9872 self test which ( according to the 9872 C service manual ) will check out the HP-IB circuit within the plotter.  I get the feeling from the service manual that the Confidence Test does not check the HP-IB, but of course I may be wrong.

If the plotter is proved to be faultless, then I will have to find another 98034, and /or a 9872A ROM.

Best regards,



I am afraid that the self test on the plotter will not be able to fully test the HPIB interface, at best it can read some registers and see that the signal lines on the interface are as expected.  The same is true of the test you used on the 98034 it is just reading some registers in the interface.  The problem is there is no convenient way to test the electronics that drive the bus and since the data bus is a bi-directional bus you cannot even do a simple wrap test.   The only way you can really be sure the 98034 is functioning is connect a known good HPIB device to it and try to talk to it, if you have a logic analyzer available to you, you could use it to observe the activity on the bus when you try to send commands to the plotter.


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