difference between LSI-11 CPU's M7264 and M7270 - test-drb@ccmp.vtda.org

26 Sep 2005

On Sep 26 2005, 13:34, Allison wrote:
...
  Pete Turnbull wrote: 
...
  > No, that's not right.  It's ordinary
serpentine.  I don't have one, but
...
  > I just checked the Microcomputer Handbook myself,
and it's definitely
...
  > like this:
 >
 >  A    B      C    D
 >       processor
 > option 2    option 1
 > option 3    option 4
 > option 6    option 5
 >
 > It's on page 6-3, and the expansion options, with the cable coming from
...
  > where I've shown "option 6", are
shown on 6-19.  It's also shown in the
...
  > same arrangement on page 426 of the Microcomputer
Interfaces Handbook.
...
    Explain
the drawings on pages 6-19 and 6-20 of the 76/77 microcomputer
...
  handbook. 
The drawings on 6-19 and 6-20 in my copy show standard serpentine, as I
drew above, ie with the last option (or, in those drawings, the
terminator/cable connector) in the bottom left.

This also matches my handouts from the DEC QBus training course I went
on in the early 80s, the diagram on page 2-4 of the 1976 Microcomputer
Handbook, Fig.3-16 "Daisy-Chain Priority" on page 3-27 of the 1983
edition of the BA11-M Technical Manual, Fig.1-9 on page 1-12 of the
LSI-11 Processor Handbook, Fig.4-2 "H9270 Option Positions" on page 4-4
of the 1978-79 Memories And Peripherals Handbook, Fig.4 "BA11-M
Expansion Box Interconnections" and Fig.5 on pages 93 and 94 (chapter
on BA11-M) of the 1983-84 Microcomputer Interfaces Handbook, Fig.2
"H9270 Option Positions" on page 367 of the same 1983-84 handbook,
ditto pages 72, 73, and 426 of the 1980 edition.

Of course many of these are copies of each other, but I'm sure if there
were an error, DEC would have corrected it at some time between 1975
and 1983 :-)

-- 
Pete						Peter Turnbull
						Network Manager
						University of York