Is PACK on the HP-71 buggy?

[rprosperi]

(08-06-2014 04:16 AM)Joe Horn Wrote:  Bottom line: Don't use the HP-71's PACK or PACKDIR unless (a) you can see with a hex editor that there is at least one entire free record (256 bytes) between the last directory entry and the beginning of the contents of the first file, and (b) you will NEVER afterwards add anything to the medium using the HP-41 HP-IL module. Otherwise data loss will occur.

One thought here. Which version HP-IL Module were you using? I've never found a definitive list of changes from 1A to 1B, but anecdotal comments here and other fora have stated that PACK/PACKDIR were 'better' in 1B than 1A, though they did not go so far as to claim it was completely fixed.

The bug descriptions on J-F's HP-71 bugs page (here) say for item 1184-1 that the PACK problem using a 9114 is due to a 9114 bug, but it seems your findings show otherwise. It is also feasible, but I think unlikely, the issue is within ILPer.

There is also a bug noted in the HP-IL addendum that came with my HP-IL (1A) manual (also noted on J-F's page) about a Memory Lost when using CAT/CAT$ if the first file is deleted, suggesting using PACK to avoid the issue. Definitely a different issue, but sensitivty of first file's proximity to the directory is noteworthy.