We use mostly 57's and a few 65's.  A typical test setup for our radio
loops involves 1-2 65's and 5-10 57's.  We erase for one hour for 57's, 1-2
for 65's.  We write a number on each chip and have a dated log sheet: one
row for each chip, one column per day.  We put an X in the box if a chip
does not program properly and just rewipe the chip  If a chip does not
program several times, we put it aside.  When we have a few set aside, we
put them through several 1 hour erase cycles.  Any that do not program
after that are junked.  We also refrigerate chips before cleaning.

COM ports: we use 1 to control a radio loop, one for a loop monitor (though
we also have a parallel port version) and one for a logic probe monitor we
designed, 8 logic probes controlled by a 57.  I also use a modem.  We
configured two COM ports with standard IRQ's and the third with
non-standard IRQ, as discussed earlier.  The modem is an internal US
Robotics WinModem, the latest X2 technology, 33.6, soon to be upgraded to
33.6 upload, 56 download.  It is plug and play, finds its own address/IRQ.