On 6/4/21 5:24 PM, Lyle Bickley wrote:
Uhh, waitaminute. Is it possibly the case that there are two
different versions of the 4145A? Or maybe that it can boot from EITHER
hard- or soft-sectored media?? The latter would be most unusual. This
is the first I've heard of this; I had assumed (sorry!) that you were
just misremembering about your 4145A's boot disk being hard-sectored.
When I got my 4145A (and a floppy diskette that would boot) I talked with the
previous owner (a senior Google Robotics guru) and he told me the 5.25" FDD
was hard sectored and would not copy on anything he had. When I got the 4145A
home, I checked the diskette - and it was easily observed to be hard sectored.
Wow, ok.
I then went online and checked this site and Googled other specific 4145 sites
and found the following, seemingly definitive, information:
...
After reading the above - and observing the hard sector diskette, I didn't
even try to copy the 4145A diskette.
That's reasonable.
I subsequently used Dunfield's "imagedisk" to make a copy of my 4145B diskette
[which I attached in an email for folks on this list].
Excellent. :-)
We should probably suss this out.
Agreed!
So yes, thank you for NOT suggesting that perhaps I don't know how to
accurately identify a hard-sectored disk. ;)
I just went and looked at it a THIRD time, because I know just how
little sleep I've been getting lately. ;) Spinning the media around
inside its jacket, there is precisely ONE hole visible through the
sensor window as the media makes a complete turn. One. And yes, it's a
5.25" disk, and the box says "4145A" on the front. It has the original
beige drive with the flip-up front door; I don't recall the manufacturer
of the drive offhand.
I wonder if I have some sort of weird variant of the 4145A? (this one
is the only one I've ever owned or directly used)
I'll have to give it a shot - I picked up the zip file 4145A image - and
have a linux/DOS (dual boot) system with both low/quad density and high
density 5.25" diskettes. (This system is only used to make copies of
"weird" FDDs).
I have one of those set up as well, with an 8" drive connected too, in
an external chassis with a switchbox and one of John Wilson's FDADAP
boards to handle the TG43 signal and such.
Yup, mine has all that, too ;)
Excellent.
That system also has a 9-track tape drive, as well as 3480 and 3490 (IBM
mainframe) cartridge tape drives, and a DEC TZ85 for reading DEC TK50 and
TK70 tapes.
I still have a DEC TK50 attached to mine -
Uh, by what interface?
but gave my HP 9-track tape drive
(800/1600/6250) to the Computer Museum of America...
Sigh...black hole...
I also use my vintage MB's integrated floppy controller - which has handled
every soft sector format I've "thrown" at it. I have HD and low density 3.5"
and 5.25" and Dual 8" FDDs. So we have similar setups (especially before I
donated my tape drive). :)
Very cool.
Not familiar with "GreaseWeazle" - but it sounds similar to the KyroFlux.
Yes, a similar idea, but a newer implementation using one of the later
crop of fast microcontrollers, and its host interface is USB. All open
source, of course.
[BTW: I'm on the PDP-1 Restoration Team at the Computer History Museum (CHM)
and have on several occasions helped the Museum copy/analyze tapes/diskettes,
etc.]
Yes, I know you're on that team. My hat's off to you! :-)
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire