The Museum of HP Calculators
HP Forum Archive 04
[ Return to Index | Top of Index ]
|Overwriting a WriteProtected Card (HP-67)|
Message #1 Posted by Mike on 18 Nov 2000, 7:22 p.m.
Is it possible to overwrite a write protected card on the HP-67? I have two Standard Pacs for the HP-67/97 but one has a couple of cards that give errors.
I thought I could just load the programs and then overwrite the card that would not read properly but I don't see anything in the manual about doing this.
Is this possible?
Second option: Can the 41 load such a program and write it back to the card using 67 instructions?
|Re: Overwriting a WriteProtected Card (HP-67)|
Message #2 Posted by Erik Wahlin on 18 Nov 2000, 8:24 p.m.,
in response to message #1 by Mike
I wrote an article about this in the articles section. Someone also pointed out an easier way to do this is to insert a unclipped card through the card exit. Then run the write protected card through the machine (with write program switch set to the left so you see the program). The unclipped card needs to be inserted far enough in from the left that it depresses the write circuitry switch. I think this is far enough in that it engages the rubber wheel. When you insert the clipped card you are writing to, the other card will get pushed out. Hope this makes sense.
|Re: hmmmm... doesn't work for me|
Message #3 Posted by Mike on 19 Nov 2000, 12:29 a.m.,
in response to message #2 by Erik Wahlin
I guess I might have to try and build up the cut corner per your article. I tried putting a card in from the other side and I can
never get the card to read correctly, once I have tried to write to the card.
If I don't put the 2nd card in from the left, I get the write error as you would expect.
If I do put the 2nd card in from the left, I don't get the write error. But, when I try to read the card back, I get an error.
I have tried this dozens of times and never get it to read back. I have also tried putting the card in from the left side at various
depths and nothing seems to work. The card I am trying to write to does push the card out of the way ok and does appear to
write (at least no errors) but it just won't read back. I have tried other cards with same results.
|Re: hmmmm... doesn't work for me|
Message #4 Posted by Erik Wahlin on 19 Nov 2000, 12:49 a.m.,
in response to message #3 by Mike
I was going from memory (which fails from time to time). The original post from the July HP museum forum was:
Posted by Bruce Cohen on 25 July 2000, 10:38 p.m.
There is a much safer and simpler way to re-record on protected magnetic cards. The technique was published in HP Keynotes long ago. All it required was to cut a waste magnetic card with a projecting tab which filled in the notched corner of the card which was to be rewritten. The cut on the waste card is made vertically with a tab projecting to the top left in such a manner that there is no appreciable gap when the two cards are butted together. To use the “re-write” card, simply push the tabbed end into the discharge of the card slot until the card makes contact with pinch roller. Then feed the protected card into the inlet slot normally to overwrite it. The newly written card will push the “re-write” card out of the slot as it is written.
HP published this to allow users to correct errors in some of the application packs.
I have used this on both the HP 67 and HP 97. I think HP said that it would also work on the HP 65 but I’m not certain. The article was published about 23 years ago and my memory may have faded due to the gradual loss of my natural cranial sun screen fibers over the years.
|It works but...|
Message #5 Posted by Erik Wahlin on 19 Nov 2000, 1:15 a.m.,
in response to message #4 by Erik Wahlin
I tried it and it works but you have to insert the waste card properly. There are basically three switches activated by nylon balls as the card passes through the reader. The first switch/ball is the motor switch. It turns the motor on. The next two switches are the file protect and head switch. These switches are located at the same (horizontal) position along the card path except the file protect switch is above the head switch. Above meaning at the top part of the card. When you insert the waste card with the protruding angled end, insert it ONLY until you feel a small resistance. If you insert it too far, you will activate the head switch and it turns the head on too early. You only want to activate the file protect switch with the waste card.
Return to Index | Top of Index ]
Go back to the main exhibit hall