>From: "Bill Sudbrink" <wh.sudbrink at verizon.net>
>
>Well, unexpected by me anyway. I've built a data sep circuit
>from that schematic I asked for advice on earlier. Works like
>a champ. I tied the circuit into a piece of ribbon cable so
>that I could pretty much attach any drive I wanted to try with
>it plus still be able to keep my OSI more-or-less unmodified
>and use the original drive. The drives I am using are a pair
>of Toshiba FDD 5451s. After testing each drive individually,
>I attached another IDC card edge connector to my setup and
>tried again. Nothing worked! Not only did it not work, it
>trashed the diskette I was testing with. Went back to one
>at a time and everything worked again. After a good bit of
>trying to figure out what was wrong, I discovered that the
>+5 volt pin in the power connector I was using for the #2 (B)
>drive had pushed out of the nylon plug so that the drive was
>unpowered. Having either of the drives unpowered on the cable
>caused the other drive to screw up. The two drives cooperate
>just fine when both have power. I don't remember ever seeing
>this kind of problem before... I seem to remember having unpowered
>drives hanging off of cables with no ill effects. I guess that
>some of the signals (write gate for instance) must be getting
>pulled low by the unpowered unit. Is this normal floppy
>behavior and I'm just remembering wrong?
>
>Thanks,
>Bill
>
Hi Bill
Remember, things are active low. If the terminator was
unpowered, it will pull the write gate to active ( trashing
the disk ). If the drive that is unpowered is not the one
with the terminator, it may not have been able to pull
the lines high enough. Still, an unpowered drive should
load the lines some. This is not a good thing.
Dwight
I have been looking for this information for a long time. I have
an XT that had never been initialized, now I can proceed. Up to
this point I had no success. Thank you!
Bill Degnan
>
>>
>> I just ran across this and thought it might be of interest for anyone
>> doing a low level format on a PC (not AT) type controllers. It was
>> taken from a February 13, 1989 issue of Tech Times that appears to be
>> a ComputerLand Confidential publication (this is a copy.) My usual
>> procedure was to unassemble C800:5 or C800:6 and G=????:? the address
>> that was a jmp instruction. I've never used the :800 or tried to
>> format a Xebec controller.
>>
>> *******************
>>
>> Company Debug Command
>> Adaptec -G=C800:CCC
>> DTC -G=C800:5
>> Omti -G=C800:6
>> Western Digital -G=C800:5 or
>> -G=c800:800
>> Xebec Series of commands
>> -l322
>> -l321
>> -o322 0
>> -l321
>> -o320 04
>> -0320 00
>> -o320 00
>> -0320 00
>> -0320 05
>> -0320 07 (use 17 if embedded servo dr)
>> At this point, the LED on the drive should come on to indicate that
>> the drive is formatting. When the light goes off, coninue:
>> -l321
>> -l320
>> The last entry should get 00 status back, indicating a successful
>> format.
>
>I remember that old Xebec routine. It was always a little
>nerve-wracking as you got no feedback until deep into the procedure. I
>have a file folder full of old hard drive/controller lore that one
day I
>should scan and make available.
>
>If I am remembering correctly, the Xebec controller was the one
>originally used in the IBM-XT machines.
>
>------------------------------
-- E N D --
>Just a few random comments:
>
> - 'Rare' Mac128..
Twas not my intention to bring about a argument on the value of Macs - I simply
happned upon one while looking for the B&H AppleII and used it as an example - I
can site many examples of Ebay items which have gone fairly well over what I
consider to be a reasonable value for the item.
> - While eBay prices are to be taken as a general mix of legtimacy, ignorance,
>greed, stupidity and outright scamming, Goodwill prices aren't that much more
>'helpful' either. Unless they have a good 'picker' doing the pricing, Goodwill
>and their ilk have a mission to sell old junk for the cheap. We've all had
>impossibly lucky finds at these places..
With anything as old and varied as the items we collect, price/value is really
in the eye of the beholder, and can vary all over the map. I happened to mention
Goodwill because it was the last place I picked up a Mac 128 (and it was a true
128) - Saw three of them go in a local newsgroup last year for under $20 each,
and could have used that example ... Also seen them go for much higher on Ebay ...
Very rarely do I see an item sell in local market for higher than Ebay, but very
often the other way around - I still assert that Ebay prices should be viewed
either with skepticism, or at least as a marker for the high end of the scale.
The sad truth is that much of the material that we value and collect is
considered worthless by the majority of people - many of the items in my
collection were donations, including some that I would place a decent $$$
value on - Ebay manages to reach enough people that somebody somewhere wants
it, and by virtue of the way it works, it sells at the highest price that
they are willing to pay (or at least just above the highest price that the
next bidder would have paid) - that doesn't mean that these prices are
indicitave of a reasonable average value for an item.
By the same token, Goodwill represents the lowest end of the scale (after all,
someone GAVE it to them) - the true average value for an item will probably
lie somewhere in between Goodwill and Ebay.
> - My favorite eBay canard re: Macs is the "I opened it up to have a look, and
>it's SIGNED on the back cover!!!!". Of course, they are all signed up until the
>Classic era (I think the sigs went away with the new case, but I could be wrong).
IIRC, the sigs were in the Original, Fat and the Plus, which are all essentially
the same plastics (with vents on top) - with the SE and forced air cooling, the
plastics changed and the sigs were dropped - Classics are the third style of small
mac plastics (also without sigs).
Regards,
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
Hi,
I used a PERQ 1 some time ago, and it would be
great to get one of these old machines up and
running again. Does anyone have one of these
for sale/trade/etc?
I'm based in CA but can also collect
>from the UK (I visit quite frequently).
Cheers
Ian.
__________________________________
Do you Yahoo!?
Yahoo! Small Business - Try our new resources site!
http://smallbusiness.yahoo.com/resources/
> Does anyone know of a program I can use (preferably under Linux, but DOS
> would probably work as well) to read a flux-transition level image off a
> disk using a catweasel card? I'm trying to read some 2.4MB (5.25")
> floppies from an IBM 3174 controller (using an 2.4MB floppy drive), and
> am able to read in 1.2MB floppies using cw2dmk just fine, but it doesn't
> do so well at processing the (aparently) mixed-density floppy I've been
> screwing with since yesterday. Using the "testhist" program included
> with cw2dmk, I can get information about the "unreadable" tracks, but
> cw2dmk won't process them. I'm trying to make a backup image of a disk
> so that I'm not screwed when the disk stops being readable...
If you give testhist one more argument (a filename), it will dump the
Catweasel's sample buffer to that file. That's a flux-transition level
image.
I don't have anything that will write such an image directly back to a
disk, though. You could write a program to do it by removing most of
the guts from dmk2cw. However, I don't know how readable such a disk
would be. I don't really trust a process that doesn't include decoding
the data, doing retries if it has a bad CRC, manually trying
read-postcompensation (-o flag to cw2dmk) if that still doesn't work,
and writing the data back with write-precompensation.
If this data is just MFM in an IBM/ISO-style format at a higher clock
rate, you probably can read it with cw2dmk by playing with enough of its
options. You'll need -1 and -2 to set lower thresholds between short,
medium, and long intervals (they should be about halfway between the
peaks that testhist gives you), and -l to make the DMK track length
twice as long as for a 1.2 MB disk. You may need to play with -o too,
especially if you can read lower track numbers but higher ones keep
getting CRC errors.
I'd also suggest using the highest (28.322 MHz) Catweasel clock rate for
these disks, seeing that you have a MK3. (The MK1 doesn't support this
rate.) You'll need to give 4 as the clock rate to testhist to get a new
set of peaks, and then give the -c 4 option to cw2dmk.
There's still not a way to write this image back, though, as dmk2cw
doesn't offer enough control from the command line. After you find a
set of parameters that work in cw2dmk, define a new kind_desc in kind.h
and recompile. You can then write disks that use these parameters with
dmk2cw, and more conveniently read them in cw2dmk using one -k option
instead of all the individual options I listed above.
Feel free to email me if you need more help.
--
Tim Mann tim at tim-mann.orghttp://tim-mann.org/
willisjo at zianet.com wrote:
> However, I am a tad concerned about what will happen
> to our prized hobby when such items as 9-track tapes,
> TK50s, and TU58 DECtape-IIs truly become absolute
> unobtainium.
As I have stated many times before, I believe the solution is for us to
open our own factories to make them.
MS
termination is 150 ohms (for 5.25" floppy drives) to +5vdc... one of the reasons that one drive only can be terminated otherwise the output drives can't handle the current and if there is no termination then there is not a valid logic high level.
best regards, Steve Thatcher
-----Original Message-----
From: Bill Sudbrink <wh.sudbrink at verizon.net>
Ah, yes, in each of my tests, the unpowered drive was set for
DS2 (drive B) and TM (termination) and was at the end of the
cable. But, I thought that the termination was to ground?
On Mar 20 2005, 19:20, Bill Sudbrink wrote:
> After a good bit of
> trying to figure out what was wrong, I discovered that the
> +5 volt pin in the power connector I was using for the #2 (B)
> drive had pushed out of the nylon plug so that the drive was
> unpowered. Having either of the drives unpowered on the cable
> caused the other drive to screw up. The two drives cooperate
> just fine when both have power. I don't remember ever seeing
> this kind of problem before... I seem to remember having unpowered
> drives hanging off of cables with no ill effects. I guess that
> some of the signals (write gate for instance) must be getting
> pulled low by the unpowered unit. Is this normal floppy
> behavior and I'm just remembering wrong?
Usually that's OK. Is perhaps the one without power also the one with
the terminators, or do neither have terminators?
--
Pete Peter Turnbull
Network Manager
University of York
> Is the H720 the correct power supply for the TC11/TU56
> combo, as is indicated in some document I've looked at?
> I'm at work and don't have my notes. Are there other
> compatible DEC power supplies that will work with the
> TC11/TU56?
>
On a related note...any special concerns on an initial powerup of a TU-56 that has not been turned on for possibly 5+ years....??
I just ran across this and thought it might be of interest for anyone
doing a low level format on a PC (not AT) type controllers. It was taken
>from a February 13, 1989 issue of Tech Times that appears to be a
ComputerLand Confidential publication (this is a copy.) My usual
procedure was to unassemble C800:5 or C800:6 and G=????:? the address
that was a jmp instruction. I've never used the :800 or tried to format
a Xebec controller.
*******************
Company Debug Command
Adaptec -G=C800:CCC
DTC -G=C800:5
Omti -G=C800:6
Western Digital -G=C800:5 or
-G=c800:800
Xebec Series of commands
-l322
-l321
-o322 0
-l321
-o320 04
-0320 00
-o320 00
-0320 00
-0320 05
-0320 07 (use 17 if embedded servo dr)
At this point, the LED on the drive should come on to indicate that the
drive is formatting. When the light goes off, coninue:
-l321
-l320
The last entry should get 00 status back, indicating a successful
format.
