HP85 I/O Rom "repair?"

[Michael O. Tjebben]

Hello-
I bought a 2nd I/O ROM recently for a second HP-85 that I have, but it doesn't seem to work. For example, it reports "syntax error" when I type output and return.

On the I/O ROM that does work, I get "invalid parameter" when I type just output and return (because I haven't given it a parameter). This is okay and expected.

My questions are:
1. The ROM that works is not marked with any "revision" information. The one that does NOT work is marked "revA".
Is there some difference in syntax for the output command that I'm unaware of?

2. If, by chance, this I/O ROM is bad, is there a way that I can replace it with a copy of a good one? (EPROM?) Has anyone disassembled one of the modules to look?

-Mike

[Vassilis Prevelakis]

Maybe its not an HP-85 ROM, the HP 86/87 ROMS look the same
but they are not compatible with HP-85 ROMs. What is the
colour of the lettering on the top of the ROM? (I think
white is 85, yellow is 86/87, but I could be wrong).

**vp

[Michael O. Tjebben]

Ah hah!
Vassilis-
I didn't realize that there was a difference! Should have known...
The I/O ROM that works for me is WHITE. The one that doesn't is YELLOW. You must be onto something here!

Maybe I'll have to see if someone will trade an HP85 I/O ROM for the HP86. I really thought they both had the same part number, but I'll take a closer look tonight.

Thanks for the information...

-Mike

[michael Tjebben]

Oh man! What a dummy! I looked at the numbers on the ROMs and they ARE 87's! I'll post an add to see if someone wants to trade. Thanks Vassilis! -Mike