COAET" • r

WILL THE REAL APPLE PASCAL PLEASE STAND UP?
by Dr. Wo
Once Upon a Time, there was only one Apple computer
and only one implementation of Pascal for it. Indeed, many
of you would probably agree with me that there was only
one personal computer and one programming language in
the world! (Note: Dr. Wo programs in Pascal. Which is a bit
like saying that Carl Sagan watches stars. -PCW)
Now, however, there are some new kids on the block.
There is probably at least one other personal computer
you'd love to hav~. But more important for Pascal pro·
grammers, there are at least four different versions of Pascal
running on two Apple computers: Apple Pascal 1.1 on the
Apple II; Apple /// Pascal; Softech Microsystems' UCSD
Pascal Version N.1, running on the Apple II and a passel of
other computers, including the new kids, and Pascal MT , a
CP /M based system covered in the March-April 1982 Apple
Orchard.
Will the Real YOU Please Stand Up?
Now, what has this to do with you? Well, with personal
computers looking more and more like appliances, in the
sense that your Old Faithful Apple II may not be the only
computer you'll ever own, the question is, how portable is
your software? That's a valid question whether your soft·
wai:e is purchased or home-grown.
Of course, your need for portability should be determined
by your objectives. What are you trying to develop for yourself?
Are you writing programs for personal use, with little
expectation of acquiring another machine on which they
might run? Are you developing software tools and/or applications
software for your own use or for sale on the open
market? Do you want those tools and applications to work
on as many machines as possible, or are they Applespecific?
Are you investing a lot of your time on programs
that you might like to run on another computer someday?
And just how soon is "someday?"
Let's Review
We'll review three of these Pascals here and now, from
two programming points of view. On the one hand, we'll
look at them for developing tools for personal use, and on
the other we'll look at them for developing applications
programs and general purpose tools, hoping to run them
on a number of machines.
Most of the review is a comparison of Apple II Pascal and
Softech' s Version N. The biggest differences, and the big·
gest choices, are between these two. We note that there are
differences between Apple II and Apple / // Pascals, and
we'll note some of these as we go along.
Apple II Pascal, Version 1.1
This is the Apple Pascal 99 per cent of us know and love
so well. Omitting some history, some additions, and some
revisions, it is essentially the Pascal operating system developed
by Prof. Ken Bowles at the University of California
-San Diego (UCSD), to which Softech's Version N also
corresponds. Apple Pascal is a delight to use, and has
several features which aid software development and maintenance.
Whatever I have learned about good (and bad!)
programming, top-down design, modular program devel·
opment, you name it, I have learned on my Apple using this
system.
There are additions to the UCSD standard Pascal system
in the Apple implementation, the most outstanding of
which is the inclusion of UNITs to aid in development of
software libraries. They are the way to group proven, logically
related data structures and procedures into a package,
which can then be used in program after program. Even if
you don't plan to use a set· of routines in more than one
program, units are still powerfully useful. They are an aid to
modular development, and can save you a lot of compilation
time as you iteratively debug, improve, and refine a
main program. Regrettably, it took me a while to realize their
value.
Four other features of the Apple operating system which I
have found useful are the EXEC files, chaining, BIOS attachment
utilities, and compiler options ·to· control the
residency of units and program segments. With EXEC files
we can drive the operating system and our programs from a
script. And with the Attach utilities (available from the International
Apple Core on a disk with booklet for $7.00) we can
integrate all manner of peripherals into the operating sys·
tern in a logical and consistent way.
If you have some foreign (read "non-Apple") peripherals
such as a Micro modem or auxilliary RAM card and have not
investigated integrating them into your system using these
attach BIOS programs, you're really missing a lot of fun
-and probably using a lot of kludges to drive the peripheral.
The attach programs are nice because they allow
you to define an Assembly language driver for a peripheral
and then access it from Pascal through the operating system's
1-0 intrinsics. You can even pass parameters to the
driver through the intrinsic "UNITSTATUS," meaning you
can exercise complete control over your peripheral from
May· June 1982 75