Path: utzoo!utgpu!watmath!att!pacbell!ames!lll-winken!uunet!zephyr.ens.tek.com!tekgen!tekigm2!neals
From: neals@tekigm2.MEN.TEK.COM (Neal Sedell)
Newsgroups: sci.electronics
Subject: Re: Xilinx
Summary: You think that's bad, wait'll you see......
Keywords: Look at those minimized equations or else (use EEPALS)
Message-ID: <5664@tekigm2.MEN.TEK.COM>
Date: 8 Aug 89 08:05:09 GMT
References: <8897@june.cs.washington.edu>
Reply-To: neals@tekigm2.MEN.TEK.COM (Neal Sedell)
Organization: Tektronix, Inc., Vancouver,  WA.
Lines: 31

Speaking (not very kindly) of programmable logic development tools, has anyone
ever tried using low true outputs with a programmable output polarity device
like a 22V10 using (un)Abel??? (I'd give the trademark disclaimer but I don't
want to embarass Data I/O.  Oops! ;-)).  I have wasted soooooo much time trying
to describe a couple of these I've done in a reasonable fashion, but the tool
is so DAMN brain-damaged that there's just no way to do it.  The manuals are
virtually useless, except for the examples, which with lots of your time you
may find enough hints in several of which to get you where you need to go.
Registered low outputs on same 22V10's are even more of a pain, at least if
you use the State_Diagram syntax.  I ended up declaring the pins as _XXX,
redefining them as XXX = !_XXX for readability, and having to declare them
as "reg, neg" in an IsType statement just to get the darn thing not to generate
NULL equations for the non-state-variable terms.  Seems to want to AND
said terms with 1 XOR !(0) (something like that) turning all the terms to 0.
If I wanted a constant level I would've just tied the inputs high or low.

   This is all on the PC version 3.10 just released, but it works the same
way on a uVAX running 3.00.  I shudder contemplating the next and last PLD
I have to do for a project, because last time both Abel and Palasm insisted
in de-minimizing my DMA state machine so badly it wouldn't fit in the target
device!  I used to use Palasm all the time but moved up to Abel since it did
address decoding so nicely.  I guess that's all it does nicely ;-).  At least
in Palasm when you defined a pin a low-true it actually took your word for it!

Flame out,

-- 
# Neal Sedell     (206) 253-5280
# aka   neals@tekigm2.MEN.TEK.COM
# Tektronix, Inc., Delivery C1-936
# PO Box 3500, Vancouver, WA  98668