Post Reply 
Eprom Modules for the HP 75
08-02-2016, 01:21 PM
Post: #12
RE: Eprom Modules for the HP 75
Meanwhile Dominique went on to produce a modern version of the ROM simulator, in order to better understand all the intricacies of the ROM addressing and bank switching schemes, and before attempting to pack the logic into the small housing of an EPROM module, which is the final goal, of course.
He has got the NoMas listings of the HP 75 operating system, but they are huge, of course, and he is not (yet) familiar with them.
Can someone (Paul?) help him to locate the part (subroutine) where the bank switching (ROM addressing) is managed; literally Dominique says:

"My objective is to locate in the source file the sub's managing the paging process depending of the number of 8k pages used by external modules. The explanation in the Simulator Manual explains only the management of one (A + B double x 8ko" banks)."

Please help us; I am convinced that, with some help, Dominique finally will succeed in producing extension modules for the HP 75, and this would be a great achievement and would lift the usefulness of this calculator to a new level, wouldn't it?

By the way: Yes, Dominique has found a solution to the connector problem, but he hasn't revealed it yet. :-)
Find all posts by this user
Quote this message in a reply
Post Reply 

Messages In This Thread
RE: Eprom Modules for the HP 75 - Michael Fehlhammer - 08-02-2016 01:21 PM

User(s) browsing this thread: 1 Guest(s)