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68000 Architecture

From Charles Richmond <numerist@aquaporin4.com>
Newsgroups comp.sys.atari.st
Subject 68000 Architecture
Date 2017-08-21 09:50 -0500
Organization A noiseless patient Spider
Message-ID <onermo$b8a$1@dont-email.me> (permalink)

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Yes, yes... certainly I know.  The 68000 architecture was shared with 
the older Macintoshes and other lesser-known computers like the Tandy 16b.

But let's *not* lose sight of the great organization and instruction set 
of the MC68000.  It had many of the features that made the PDP-11 
architecture popular with programmers.  And the LINK and UNLK 
instructions were great for calling subprograms!

Although the actual machine code was much different, many of the 
assembly mnemonics for the 68000 resembled the mnemonics used by the 
PDP-10 assembly language.

My Atari ST was the first computer I owned that could run *real* 
compiled programming languages like Pascal and C.  That helped me 
sharpen my programming skills and gave me the realization that 
microcomputers were going to be running things in the future.

The Usenet groups in the 1990's posted the source code for Atari ST 
programs and were instructive to budding computer coders.  I remember 
that the Atari ST source code groups would have much more code than the 
Amiga group... probably because the Atari was cheaper and easier to buy 
for a lot of folks.

I remember writing a program to print out the Mac graphic files on an 
Epson-compatible (Panasonic) 9-pin dot matrix printer. Once the picture 
file is decompressed in memory (the 1040 ST had enough memory to keep 
the *whole* picture in memory at one time!), the trick was to "pull out" 
the pixels 8 at a time in *vertical* order...  the way the printer 
wanted to receive the pixel data.

I too converted a program in Algol (published in the Nov/Dec issue of 
Creative Computing magazine) into OSS Pascal...  that would draw Koch 
"snowflakes" on the monitor screen.

https://en.wikipedia.org/wiki/Koch_snowflake

http://www.aquaporin4.com/snowflake/

I put together a program to use the entire monitor screen to plot an 
Ulam spiral, which is a depiction of the distribution of prime numbers.
Although simple in concept, *many* primes have to be plotted to be able 
to recognize the linear pattern in the picture.

https://en.wikipedia.org/wiki/Ulam_spiral

-- 
numerist at aquaporin4 dot com

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68000 Architecture Charles Richmond <numerist@aquaporin4.com> - 2017-08-21 09:50 -0500

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