I went down this rabbit hole when I bought my HP4145A.
I had images of the disk, as read by the jack-of-all trades
disk copying program, ImageDisk, that runs under DOS. So,
I naively thought that if I bought an old DOS computer that
had 5-1/4" disk drives, I should be able to make the bootdisk
for my 4145A. The author of the program indicated that the
IBM PC disk controller was too fussy for this sort of use,
so, I acquired a Compac Portable (luggable) computer.
After refurbishing the disk drives so that they were again
reliable... one lost the adhesive on its internal disk speed
tachometer label.., and proving that they now worked reliably,
I fired up a copy of ImageDisk, by Dave Dunfield... a DOS
program known to be able to copy the 4145A floppy disks, and
set to work.
Dunfield warns:
"In developing ImageDisk, I have tested with dozens PCs, and
found that only a few of them could read and write all the mixed
density formats that I was able to make work. Some could read
all the formats (with a high number of recoverable errors) but
could not write them all. The remainder could not even read all
the formats.
He further goes on to say that you may have to try a number of different
PC's to find one that can both read and write all of the formats.
He also says that sometimes you can get better success if you slow
down the motor on the disk drives to allow the CPU enough time to
work....
Dunfield states somewhere in his tome that the PC/AT floppy controller
can write most everything using a 1.2Mb floppy, using trickery...
I will leave that experiment for another day, as my last 1.2Mb drive
is unreliable at this stage of its life... it needs cleaning and
probably lubrication.
A rabbit hole that I ultimately quit playing in.
-Chuck Harris
On Thu, 3 Jun 2021 21:45:49 -0400 "Dave McGuire"
<mcguire@...> wrote:
On 6/3/21 8:54 PM, Lyle Bickley wrote:
In what ways is the 4145B an upgrade from the 4145A? The B seems
to sell for quite a bit more money. But, a quick look at the manual
specifications seems to indicate they have similar capabilities. I
understand the floppy drive was changed? Anything else? Are there
digital upgrades to the B unit?
The "A" version uses a 5.25" diskette drive. The boot diskette is
hard sector with a weird format that I've not been able to copy.
The original, working, HP-labeled boot disk in my 4145A is *not*
hard-sectored.
-Dave
