HP-41 <> USB-41 bidirectional comms.

[Diego Diaz]

Hi again,

And thanks for your kind words and your contributions.

I'm affraid my notes were not much clear regarding some of the limitations of this communication SW.

The main one, (which I think is the cause it has failed on the CL attempts to Receive a page) is somehow "hidden" in the comment regarding the source/destination page numbers: since the page sent form PC to HP-41 *must" use page #7 as the source; page #7 must be empty! Otherwise random data is to be transmitted and therefore chances to crash due to polling points erratic behaviour.

Since most CLs make use of page #7 it won't work as expected.

The same incompatibility applies to the HP-IL module.

The printers (either IR or 82143A) will cause same problem too. Although printer code itself goes to page #6, it forces HEPAX code to be placed into page #7 with similar results.

I'm working in the mods to allow usage of page #F instead, which I hope to be far less conflictive.

My apologies for not making this point clearer on first instance.

Not as serious as the above one but still a bug, it seems that in some occasions, the last word (namely the last byte of the checksum) of a page is not transmitted to the PC, rendering a 8,191 bytes .ROM file.

Although I haven't yet found the origin of such bug, it can be easily overcome and next version of the SW will prevent this from happening.

Thanks again for your support and contributions and best wishes.

Diego.