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Trying to recover 67's prerecorded magnetic cards
08-22-2021, 02:31 AM
Post: #21
RE: Trying to recover 67's prerecorded magnetic cards
(08-16-2021 05:34 PM)aurelio Wrote:  
(08-16-2021 05:18 PM)teenix Wrote:  Maybe the magnetic strip has deteriorated over time and data can't be stored reliably anymore. I don't know if these can be refreshed by deguassing or not.
cheers
Tony
I don't think so, if it works as for the HD I read that "a degaussed drive is inoperable in any system. The magnetic erasure rearranges the magnetic field to such an extent that standard read heads are unable to find a magnetic reference point for tracking.", so that "a degaussed disk cannot be used after degaussing".
HDs have a servo platter/surface with timing and sector information magnetically written on them so degaussing destroys that and the disk is useless. These carts are more like a normal mag tape (or cassette tape) test has no pre-recorded info on them that can;t be put on by the normal device used to read/write from the medium. The servo info can’t be accessed by the normal disk heads.-kby
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08-22-2021, 02:40 AM
Post: #22
RE: Trying to recover 67's prerecorded magnetic cards
(08-17-2021 02:45 PM)aurelio Wrote:  
(08-17-2021 12:59 PM)Sylvain Cote Wrote:  Aurelio,
I have almost all the HP-65 & HP-67 application pac in my collection.
Several cards, about a dozen, are not working anymore and nothing can revive them.
Sylvain
Thank-you Sylvain (sob....)
Aaaarg..... so the only way is to write onto a new card, entering manually each line of the program, step by step and using the original card merely as overlay for the A, B,C, D,E keyes Smile

Or find someone with a readable version of the card. Maybe list which ones you need…you might at least get some. I have several 67/97 pacs although nothing unusual.

Generally I have found magnetic fields to be the biggest culprits these days as so many devices have magnets in them. They’re not very strong ones but at close range, the cards seem to erase easily. The real bummers are the cards that can’t be keyed in snd require some special techniques to write (which abuse the card reader). I also tend to keep copies in a metal can. However, this won’t destroy the card permanently.

Magna-see (iron filings in trichloroethylene) might give you an idea if it’s a bad spot on the card or something.

Is it bad on both sides?
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08-22-2021, 11:48 AM (This post was last modified: 08-22-2021 04:25 PM by aurelio.)
Post: #23
RE: Trying to recover 67's prerecorded magnetic cards
(08-22-2021 02:40 AM)[kby] Wrote:  Or find someone with a readable version of the card. Maybe list which ones you need…you might at least get some. I have several 67/97 pacs although nothing unusual.

Generally I have found magnetic fields to be the biggest culprits these days as so many devices have magnets in them. They’re not very strong ones but at close range, the cards seem to erase easily. The real bummers are the cards that can’t be keyed in snd require some special techniques to write (which abuse the card reader). I also tend to keep copies in a metal can. However, this won’t destroy the card permanently.

Magna-see (iron filings in trichloroethylene) might give you an idea if it’s a bad spot on the card or something.

Is it bad on both sides?
Actually never I cared too much about the letal presence of magnetic fields due to common electrical devices used daily at home,I've not permenent magnets in my home, and I always kept calculators and related stuff, safely and not near even to speakers, as I can remember but I will follow right now, the advice to keep them into a metal box...it's surely better this way
I'm not the first owner of this pack, it came years ago with a 67 wich I bought in the US and tried to repair (card reader issue) and I got definitively succes with the help of a friend of mine really skilled in repairing this and other machines like the HP97.
meanwhile I had tested the pack with the help of 41's, 97 or another 67, finding that part of the cards was defective.
Maybe not the entire package but a few cards (the ones in the first holder maybe), could been left exposed to a magnetic field, by the previous owner, I don't know it actually I thought it could be just a problem of oxidation.

These cards are bad on both sides, I think , 'cause I get "Error" reading on both the sides...

Edit: typos
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08-22-2021, 01:59 PM
Post: #24
RE: Trying to recover 67's prerecorded magnetic cards
Actually there are many more permanent magnets around nowadays then in the 70s and 80s. Take, for example, the cover of my tablet, which is magnetically attached to the tablet. I frequently see paper-clicks attached to the cover. Even the power plug of my Mac is magnetic.

So if you have magnetic cards lying around, you have to be aware of all these magnetic traps and keep your cards safely tucked away. Keeping them in a box (even non-metal) sounds like the best advice. You keep them there and only take them out when you need them and then put them back.

Vassilis

http://www.series80.org
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08-23-2021, 03:09 AM (This post was last modified: 08-23-2021 03:11 AM by [kby].)
Post: #25
RE: Trying to recover 67's prerecorded magnetic cards
Yes, these are the things I’m thinking of. Apple laptops (maybe others) generally sleep when the lid is closed with the laptop on. This is accomplished with a Hall effect sensor in the keyboard/trackpad area and a magnet in the lid. The same is true for iPad covers that put the tablet to sleep. It’s very hard to be always aware of this. The “smart connector on iPad Pros has magnets. In recent model iPad pros the attachment of the Apple Pencil stylus to the tablet for inductive charging is uses a magnet. I had previous cards erased by having them close to a case that used magnets. Placing the tablet on top of the Kangaroo case of a -65 with cards in the front pocket can be enough yo render them unreadable. Remember, you don’t have to totally erase the card to make it unreadable; just done of it.

That still doesn’t address why the cards can’t be rewritten. That’s more likely mechanical wear or something else that caused oxide to flake off. Again, doesn’t have to be everywhere.-kby

(08-22-2021 01:59 PM)vassilisprevelakis Wrote:  Actually there are many more permanent magnets around nowadays then in the 70s and 80s. Take, for example, the cover of my tablet, which is magnetically attached to the tablet. I frequently see paper-clicks attached to the cover. Even the power plug of my Mac is magnetic.

So if you have magnetic cards lying around, you have to be aware of all these magnetic traps and keep your cards safely tucked away. Keeping them in a box (even non-metal) sounds like the best advice. You keep them there and only take them out when you need them and then put them back.

Vassilis

http://www.series80.org
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