3 Feb
2004
3 Feb
'04
10:24 a.m.
Hi Chris
The answer is absolutely maybe. It really depends
on the original cause. Try running some test with
a known good drive.
You didn't state what you were running on? Things
like Nortons disk doctor have good serface test.
Dwight
From: chris <cb(a)mythtech.net>
Will a magnetic bulk eraser restore a floppy to good status?
I have some floppies that are reporting bad sectors when formatted. I've
tried bulk erasing them, and a format afterwards reports no bad sectors.
Is this actually working, or am I just getting lucky, and those bad
sectors will return shortly.
These are DSDD 3.5's which are getting a little harder to come by. So if
bulk erasing works, then I'll do that and salvage them.
-chris
<http://www.mythtech.net>
3 Feb
3 Feb
4:04 p.m.
New subject: Help needed: AS33 understanding Reader Run Control
Hi,
in the process of restoring one of my teletypes I decided
to connect it to a PC. Send and receive work fine, but the
tape reader does NOT work in line mode (local is no problem).
It is an ASR33 relabeled by HP and has a HP Reader Run Control Card.
I have put a schematic of this card online
http://pdp8.de/download/HPtty.pdf
(Couldn't figure out the types of T1 and D1 - so these can be a pnp or
a zener diode also. Polarities of reader run signals (RDR+/RDR-) can
also be wrong.)
But I am too dump to understand how to connect the reader run signals.
I'm not even sure what levels they should have.
I just thought that a circuit identical to TX (on PC side aka RX on
teletype) should do.
If you need additional infos to help please let me know.
TIA
Gerold (pdp8.de)
4 Feb
4 Feb
1:58 a.m.
New subject: Help needed: AS33 understanding Reader Run Control
Hi,
it must have been far too late this morning.
After a little sleep,
I found out what went wrong.
Both sides HP in the Reader Run Control an I in the
RSR232 -> 20 mA converter made assumptions on how
the other end handles the signals.
HP thinks TX+ (positiv wire of transmit) is permanently
tied to Vcc and TX- is floating (on signal).
And RX- (negativ wire of receive) is permanently tied to
GND with TX+ floating.
I did it the other way - tying TX- to GND and RX+ to Vcc.
So the reader run control could not work.
I now will rework my converter box and show the result
(if wanted).
Thanks to all who answered
Gerold
Gerold Pauler schrieb:
Hi,
in the process of restoring one of my teletypes I decided
to connect it to a PC. Send and receive work fine, but the
tape reader does NOT work in line mode (local is no problem).
It is an ASR33 relabeled by HP and has a HP Reader Run Control Card.
I have put a schematic of this card online
http://pdp8.de/download/HPtty.pdf
(Couldn't figure out the types of T1 and D1 - so these can be a pnp or
a zener diode also. Polarities of reader run signals (RDR+/RDR-) can
also be wrong.)
But I am too dump to understand how to connect the reader run signals.
I'm not even sure what levels they should have.
I just thought that a circuit identical to TX (on PC side aka RX on
teletype) should do.
If you need additional infos to help please let me know.
TIA
Gerold (pdp8.de)
9:22 a.m.
There are also chemical/mechanical problems with magnetic media; the
binder that holds the iron oxides to the mylar substrate fail over time.
eg. the bits physically flake off. I would guess it's highly
brand-dependent, and secndarily by handling, flexing, temp, envionment,
as Dwight sez, an absolute maybe!
On Tue, 2004-02-03 at 13:24, Dwight K. Elvey wrote:
Hi Chris
The answer is absolutely maybe. It really depends
on the original cause. Try running some test with
a known good drive.
You didn't state what you were running on? Things
like Nortons disk doctor have good serface test.
Dwight
From: chris <cb(a)mythtech.net>
Will a magnetic bulk eraser restore a floppy to good status?
I have some floppies that are reporting bad sectors when formatted. I've
tried bulk erasing them, and a format afterwards reports no bad sectors.
Is this actually working, or am I just getting lucky, and those bad
sectors will return shortly.
These are DSDD 3.5's which are getting a little harder to come by. So if
bulk erasing works, then I'll do that and salvage them.
-chris
<http://www.mythtech.net>
7474
days inactive
7475
days old
3 comments
3 participants
participants (3)
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dwight.elvey＠amd.com -
gerold.pauler＠gmx.net -
tomj＠wps.com