Re: Low-level vs. High-level programming (was My First Computer)

["M. Pender" <mpender@hotmail.com>]

Michael J. Mahon <mjmahon@aol.com> wrote in message
20030724183549.28226.00000581@mb-m24.aol.com">news:20030724183549.28226.00000581@mb-m24.aol.com...
> Michael Pender wrote:
> >
> >Apple Pascal was a half-baked implementation of the language that offered
> >very limited system access.  It was a compiled Fortran program that
> >inherited all of the limitations of the Fortran language, as well as
those
> >of Pascal.
>
> No.
>
> UCSD Pascal was a microcomputer adaptation of Wirth's ETH Zurich
> portable Pascal implementation (based on P-code).  In the process
> of adapting it to microcomputers, the biggest problem was memory
> space, so it is painfully optimized toward saving space at the clear
> expense of a regular P-code.
>
> Later, a FORTRAN implementation was done (in Pascal) which
> used the same P-code interpreter as Pascal.
>
> >For example, a program could not have more than 3 files open at once,
> >system-wide.
>
> Pascal certainly has many limitations as a system programming
> language (many of which were conscious tradeoffs made to enhance
> its educational value, in the eyes of its creator).  Limitations like the
> number of simultaneously open files are not language limitations,
> but implementation limitations--another consequence of optimizing
> for very small memory (64KB) systems.

As I said, Apple Pascal was a half-baked implementation that only allowed
three files open at the same time.  In general, Pascal was a relatively
powerful programming language 10 years ago.  However, Apple's limited
implementation left a *lot* to be desired, even for its day.

For example, I mentioned that AP only allowed three "files" to be open at
the same time.
- one "file" was needed to gather keyboard input (stdin)
- a second "file" was needed to write to the monitor or printer (stdout)
- the third "file" was really the only I/O channel available to a program
without sacrificing the ability to accept user input from the keyboard or to
send output to the display (or printer)

Thus, a program that actually interacts with the user could not have more
than one file open for reading/writing at a time without dynamically
sacrificing one of the I/O streams.  And if a program crashed without
reconnecting either of the stdin/stdout streasm you had to reboot to regain
control of the machine.

That is the standard I/O implementation of ForTran 77 -- which leads me to
believe (but does not prove) that Apple Pascal was written in Fortran,
whether or not Apple had a commercial ForTran product in the box at that
point in time.

I stand by my previous statement that Apple Pascal was a half-baked
implementation.

- Mike