HP-71B MultiMod ROM Emulator User Manual

[mfleming]

Hi Sylvain,

To quote Chico Marx, "Who you gonna believe, me or your own eyes?" The configuration string shown works in real hardware. One of the interesting things I've learned during this project is that the available documentation on the 71B is not just incomplete but in some cases wrong, or at least ambivalent and open to interpretation. The EOM flag in nib 5 marks the end of all resources, right? Wrong. It marks the end of a module, but who would think of more than one module per port, right? FRAM71. The 71 actually sends out an ID command following an EOM as a check to see if anything else is out there - consider it a hardware sanity check. I've also seen it send an Unconfigure command after setting an invalid DP address just to see if the hardware target doesn't respond to a read afterwards. Very clever, those developers.

My early misunderstanding of the discovery process resulted in an infinite ID/CONFIGURE loop. Big fun!

Yes, the remaining fields in a table entry are used as markers as well as holding precomputed values to speed command processing (the Addr field is populated during boot).