Aharpo.673
net.draw
utzoo!decvax!duke!chico!harpo!jea
Thu Nov 19 12:48:42 1981
LSL in UCDS
Notes on LSL:
1) The LSL facility for UCDS seems to work acceptably
for poly-cell generation when all inputs (and outputs)
are used.
2) When a pin is NOT used the "missing pin" diagnostic
is printed and the pin is skipped:
This is an incorrect action because when positional
notation is used, unused pins should be marked by
consecutive commas (essentially a null signal name).
FIX:
In ./cdm/L.c put a 'prs(",")' statement before
each 'missing(src)' call (and recompile).
3) Some programs (notably those used by the WH EID for
test-vector generation of TTL) use keyword notation
rather than positional notation. This requires that
each signal be assigned to the appropriate pin number
as follows: P4=SIGNAL3, which will assign pin 4 to
a signal by the name of "SIGNAL3". This is as opposed
to the postional notation which would require only
the signal name. I have added a '-k' option to
cdm -L which will use this notation rather than the
default. It uses the absolute value of the pin number
(see below) since it is used only for wiring physical
packages (as opposed to poly-cells).
4) Creating LSL for TTL (74xx00...) is not easy!!!
The problem is that the LSL program requires negative
pin numbers for the input pins.
a) If pin numbers are used in the schematic this will
make the schematic messy.
b) Wrap and Place may not like negative pin numbers?
(I haven't tried this)
c) The available libraries don't use this notation
d) Part of the LSL generation procedure uses the sort
program to order the pins. If negative pin numbers
are used for the input pins, these will end up being
sorted by inverse absolute value (ie. if pins 2 and 9
are inputs, pin -9 will be defined before pin -2).
(The keyword notation gets around this problem.)
FIX: ???
i) make the cdm program smart enough to translate positive
numbers to negative.
COUNTERPROBLEM: the polycells use +1 and -1 on the same
device!
ii) modify cdm -L to extract I/O information from the
plh library.
iii) always use keyword notation for TTL descriptions, and
use pin names (not numbers) for the drawing. Then either
modify wrap and place to accept negative numbers and
change the pins library, or make two separate libraries one
for wrap and one for LSL.
iv) to use positional notation, create an LSL library that
has dummy pin numbers designed to make the pin numbering
come out the same as the LSL parts library that you are using.
(eg. if your LSL library expects input pins 3, 1, and 6
in that order for the A inputs,
the real assignments might be:
.tp A1 1
.tp A2 3
.tp A3 6
but the LSL .tp line would be:
.tp A1 -2
.tp A2 -3 (note that after sorting, this will come out first)
.tp A3 -1 (note that after sorting, this will come out last)
v) OTHER???? HELP!!!!
-----------------------------------------------------------------
gopher://quux.org/ conversion by John Goerzen <
[email protected]>
of
http://communication.ucsd.edu/A-News/
This Usenet Oldnews Archive
article may be copied and distributed freely, provided:
1. There is no money collected for the text(s) of the articles.
2. The following notice remains appended to each copy:
The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996
Bruce Jones, Henry Spencer, David Wiseman.
