HP82161 tape drive problem



I just bought my second 82161A tape drive on EBay.

I received it, cleaned the head and I tried to test it. But the behavior of the unit is strange.

I have one tape which was written by someone else and I can read from that tape without any problem.
But when I am trying to format a new tape (NEWM 064 for example) I am getting "MEDM ERR" message.
When I am trying to write something on the tape, where already are some programs, the WRTP is without any error message and the written file name can be seen in the DIRecory listing. But when I am trying to VERIFY it or read it with READP, I am getting "MEDM ERR".
But I can delete the file with PURGE without any problem.

Also, sometimes when I am trying DIR, I get the "MEDM ERR" message, but when I try the DIR once more, I get the listing without a problem.

Anyone have some idea what can be wrong ? I tried several tapes.
Also, when I bought my first unit almost two years ago, I had (and still have) the similar problem with the first unit. Tapes can be read, but not written.

Is it possible that something is wrong with my HP-IL module ? Or maybe the head of the new unit is magnetised ? Or some mechanical problem ?


Do you retension your tapes? Advancing the tape to the end and then rewinding to the beginning? If you don't, this might be the problem, considering that it is intermittent and occurs with both units. The 82161A manual doesn't address this (maybe these tapes are less prone to the problem) but manuals for machines like the 9825 do. I know the 82161 tapes work completely differently (the 9825 type tapes are driven by an internal belt) but just from my experience with audio cassette tapes, I think there is a tendency for wound tape that has been unused for a while to stick at the edges, layer to layer - especially since these tapes are getting old! Formatting (NEWM) moves the tape through the whole range (but of course overwrites the data). Also, if the tape is sticking, the format put down by NEWM might be marginal due to momentary variations in the tape speed while the format was being written. This could cause marginal operation until the tape is re-formatted. If this was the case, executing NEWM twice might help, allowing the first pass to retension the tape. I wrote a program to move the tape to the end and then rewind it when I was learning how to use the HPIL Devel. ROM. The tape needs to be formatted for the Seek operation to succeed:

02 1
03 LAD ;I had only the tape drive connected
04 4
05 DDL ;DDL4 = Seek
06 0 ;track (doesn't matter which you use)
08 255 ;last record
10 LBL 01
12 X=0? ;not busy, no error (seek finished)
13 GTO 02
14 GTO 01
15 LBL 02
16 STOP ;pause between seek and rewind, just press R/S
17 1
18 LAD ;again, I had only tape drive connected
19 7
20 DDL ;DDL7 = Rewind
21 LBL 03
23 X=0? ;wait till rewind finished
24 GTO 04
25 GTO 03
26 LBL 04
27 '*** DONE ***
29 END

I guess I didn't know about "X(not equal)0"! The Extended I/O ROM has LAD and DDL and I think you can use OUTXB in place of OUTBIN. INSTAT is in the HPIL Module ROM.


How are you powering the unit? I used to power mine with a bench power supply that didn't have enough amperage and it caused strange behavior.



Hello Andy,

I am using the adapter which have the same parameters as the original one. Except that my adapter is for 230V.

The original is 110V -> 8V/3W mine is 230V -> 9V/300 mA

But thank you for the idea. I will test the unit with my benchtop power supply. It is regulated from 0-30V and from 0-5 A and I also will try to measure the current.


Hello Ellis,

thank you very much, but the retension of tapes did not help. The behavior of the tape unit is the same.


Remember that these machines need a good battery pack installed for proper operation... even when connected to the AC.


1) after long storage, it could be a "magnetizing problem" of the tape-head. may be, demagnetizing of the head will do the trick (there are special demagnetizers for tape decks and alike available. maybe, you can borrow one from your local radio store?)

2) tapes wear out after time. i.e., the glue that holds the magnetizable powder on the tape will start to decay (i think, normal lifetime is just about 5 years or so) --> loss of magnetic particels -->loss of information on the tape surface. (hmmm, but where to get a "fresh" tape from?? --> i dont know)


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