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HP75C I/O Rom Essential for HP-IL?
09-09-2020, 12:09 PM (This post was last modified: 09-09-2020 12:10 PM by pamphonica.)
Post: #1
HP75C I/O Rom Essential for HP-IL?
I've finally got my HP71B working well through an HP82169A HP-IL/HPIB interface to some testgear. Thank you Martin Hepperle for the 3D-printable connector designs so I now have enough cables!

I was wondering about doing the same on an HP75C, which does have HP-IL hardware built-in. But can I do anything with HP-IL without the I/O Rom? If not, that may make the project rather pricy! HP75Cs without ROMs are quite cheap. But I/O ROMs are rare.

(BTW if anyone in UK/Europe does have a suitable HP75C with I/O ROM for sale at a reasonable price, please contact me.)

Thanks
Jeremy

Jeremy. HP restorer/collector/user. HP85/86/87 and HP41/71/75. HPIB and HP-IL testgear and peripherals.
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09-09-2020, 12:31 PM
Post: #2
RE: HP75C I/O Rom Essential for HP-IL?
The I/O ROM is not required to do basic HP-IL operations, the 75C has core capabilities built-in, however the I/O ROM basically is required to do most non-trivial things. Also, even with the I/O ROM, HP-IL capabilities of the 71B are still better and can't be matched, though you probably can accomplish most everything you need to do.

Also, the I/O ROM adds many capabilities to the 75C beyond pure I/O features, it's really more of an I/O & Advanced Programming ROM, and you should get one if you plan to do much with the 75C; everything is easier with this great ROM.

You can explore all this using JFG's emu75 with the I/O ROM, utilizing virtual I/O with IL-Per or pyILPer to better understand how much this ROM adds. It won't let you talk to HP-IB devices, but it will let you learn more about using the 75C, which is fairly different from the 71B, despite their initially obvious similarities, while waiting to get an I/O ROM, which are relatively rare, and hardly ever cheap.

--Bob Prosperi
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09-09-2020, 01:09 PM (This post was last modified: 09-09-2020 01:12 PM by Sylvain Cote.)
Post: #3
RE: HP75C I/O Rom Essential for HP-IL?
Before the I/O ROM there was the 00075-13013 I/O Utilities Solutions Book who contains the HPILCMDS lex file which added the SENDIO and ENTIO$ words allowing you to send and receive raw HP-IL commands on the loop.
Sylvain
PS: you must register (free) on groups.io site and be member of the HP75 group to have access to the above link.
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09-15-2020, 06:41 PM
Post: #4
RE: HP75C I/O Rom Essential for HP-IL?
(09-09-2020 12:09 PM)pamphonica Wrote:  I was wondering about doing the same on an HP75C, which does have HP-IL hardware built-in. But can I do anything with HP-IL without the I/O Rom? If not, that may make the project rather pricy! HP75Cs without ROMs are quite cheap. But I/O ROMs are rare.

Hi Jeremy,

The HPILCPMDS lex file that Sylvain mentioned allows you to do most tasks you'd want to do with HP-IL. It is lower level than the I/O ROM and hence writing code for it is more of a pain.

Even though I don't have an I/O ROM I still managed to use my 75C with HP-IL controlling the 82186A modem, HP 82164A RS/232 etc.

Specifically I used the 82164A to drive a serial plotter (HP-7220C).
You can see the video and find out more about this in my youtube video at: https://www.youtube.com/watch?v=r0sL62EWkhY

Vassilis
http://www.series80.org
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09-20-2020, 05:02 AM
Post: #5
RE: HP75C I/O Rom Essential for HP-IL?
One of the things I truly regret selling some years back.
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10-30-2020, 07:36 PM
Post: #6
RE: HP75C I/O Rom Essential for HP-IL?
Thank you all for the information. I'm currently trying to get a 75C and this reassures me that I can get some of it working at least!

Jeremy. HP restorer/collector/user. HP85/86/87 and HP41/71/75. HPIB and HP-IL testgear and peripherals.
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10-31-2020, 05:15 PM
Post: #7
RE: HP75C I/O Rom Essential for HP-IL?
There is an HP-75c auction on eBay with an I/O Rom starting at $125.

I have no affiliation to the auction.
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