27 Jan
2013
27 Jan
'13
3:36 a.m.
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.
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