Tony Duell wrote:
I agree with
your recommendation. These days, I doubt if anyone
uses a 1 MB DSDD 8" floppy to archive files, so the exercise is
That depends on the machine. I certainly use them on PERQs and PDP's
By the time I was able to acquire my first Maxtor ESDI drive at 600 MB,
a 1 MB DSDD 8" floppy was neither cost effective nor very convenient.
But if you still use a DSDD 8" floppy for archiving files, then the more
power to you. One of these years, I must check that I have archived
the 2 feet of DSDD floppy media that I still have on my shelf. There
must be 200 MB of file there, but many duplicates I imagine.
most likely to
demonstrate a system's ability to function.
BUT, 30 years ago, that 1 MB DSDD 8" floppy was valuable
and a user might have had sufficient reasons to use just the first
side of the media on an RX02 and both sides at other times in
an RX03. So both index holes would have been useful.
Better yet, as I suggested, place a DPDT switch into the detection
circuit and any single sided media becomes double sided with a
flip of the switch - no additional index holes to mess up the jacket!!
This works if you want to use a DS disk as SS in a DS drive. I believe
the OP has a single-head drive with just one index sensor, so you can't
swich the sensors round electrically.
Since the 8" (Emulated) RX03 floppy drive in the DSD 880/30 had
two sensors, the big advantage of the DPDT switch was the ability
to use a SSDD 8" floppy media and deceive the system into accepting
it as a DSDD 8" floppy without the bother of punching a separate
index hole. Fortunately, a DEC RX02 would still be able to use
the first side as a SSDD media with just 988 blocks since the
DEC DY(X).SYS device driver in RT-11 for the RX03 (the extra
code remained in the RT-11 distributions until V04.00 of RT-11 in 1980)
used all of side one of the floppy before using any portion of side two.
Quite likely, DEC expected to sell an RX03 at one point, but never
finished the process. If I remember correctly (it was more than 20 years
ago), the extra RX03 code in the DY.MAC file from V04.00 of RT-11
had at least one bug that had to be corrected before that code would
work with the RX03 in the DSD 880/30 drive. So it is possible that
the DEC RT-11 developers never did a full test of an RX03 - or maybe
that no one bothered to fix that bug in the DY.MAC file before it was
distributed since DEC was never going to sell an RX03 in any case.
Just a bit of historical information at this point which no longer matters.
Jerome Fine
