HP75C I/O Rom Essential for HP-IL?

[rprosperi]

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.