27 Jan
2013
27 Jan
'13
4:50 a.m.
On 1/26/13 8:36 PM, Jerome H. Fine wrote:
I just looked up the dates on the modifications made by DSD to the
DY(X).SYS device drivers in RT-11. The files on the 8" floppy
disk supplied with the documentation for the DSD 880/30 range
from November 10, 198 to September 21, 1982. The bit in the CSR
has the symbol defined as:
DBSID2 = 2
The DEC RX02 does not make this bit available in the CSR since
there is no second side. However, the file DY.MAC from the V04.00
binary distribution in 1980 contains at least some of the code that would
be needed to support an RX03 DSDD drive. It does not look as if that
code was ever properly tested since I remember noticing at least one
mistake when I enhanced the DY(X).SYS device driver code supplied
with V05.00 binary distributions to support the RX03 8" floppy drive
on the DSD 880/30 that I had modified with the DPDT switch I made
mention of in an earlier post.
Fred, does that clarify the "SS/DS bit" reference?
Up until 1985, the DEC PDP-11 had hardware and software which
far surpassed any PC hardware and software. Of course, it was also
much more expensive, probably overpriced and the volume relatively
low, to some extent the direct result of the high cost.
Jerome Fine
It seems the Xerox 820 was pretty pricey too at the time. With the
configuration I have, (DSDD floppy drive and 10 mb. hard drive), it
was around $9200.00 with the stock software package and all the
hard copy documentation. Pretty steep for a desktop machine even
then. :-)
Dave Land
Land Computer Service
On Friday,
January 25th, 29013 at 6:22:30 PM - 0500, John Wilson wrote:
On Fri,
Jan 25, 2013 at 11:43:49AM -0800, Fred Cisin wrote:
What "SS/DS bit"?
Whatever your system has to read the the "TWO SIDED" signal (which is
pin 10
on some 8" drives). That's how the drive tells you which of the two possible
photocells is seeing index[/sector] pulses. Great idea, not always usefully
implemented, and missing on minifloppies.