Jon (j_b) wrote,
Jon
j_b

Atari 8-bit "Archimedes Spiral" demo - Found again!

Sometimes you stumble upon what you were looking for by accident ...

When I was 9 or 10 years old, I didn't have a modem, much less access to the Internet. The few computer magazines I had, I read over and over - and would have to type in games from program listings. I remembered typing in a BASIC program full of complicated math I didn't understand. The resulting program would take hours to run, but produced an impressive 3-D wireframe image. (With hidden line removal!)

7 years ago (mid-2008) I decided to poke around the Internet and ask in various places if anyone had seen it ... with no luck.

I had a bit of luck a year later, and posted my findings here on LiveJournal.

Today I was reading through some .PDFs of old Atari magazines, not even thinking of this, when lo-and-behold, there was the article. Hazzoo-huzzah! It turned out not to be MACE Journal or Compute, but a 1982 issue of ANALOG Computing - #7, the one with the awesome Blade-Runner inspired cover art. Many thanks to Charles Bachand, and editor Lee Pappas for the article!

I wonder if Charles is reachable... and if he remembers where he got the code for the demo...

The image I found before (in a Commodore PET accessory ad) appears in Compute! issue 12 (May 1981)10 (Mar 1981) ... the ad is from Micro Technology Unlimited ... and the May 1981 issue has a screen-dump utility by MTU employee Martin Cohen, author of their Keyword Graphics Package. Hmm! (Neat aside: he thanks Gregory Yob for help in his code!). Other snippets of code floating around the 'net include a "HAT.BAS" claiming "Originally programmed August 1982 by Bourn & Fruhwald", but the Compute! ad invalidates this claim.

Those with too much time on their hands are encouraged to look at the issue on Internet Archive - A.N.A.L.O.G. Computing magazine, issue 7 (1982) pp60-61. (Thanks to Brewster Kahle, Jason Scott, and others for their work there!)

Analog_Computing_07_1982-p60 Analog_Computing_07_1982-p61
A.N.A.L.O.G. Computing magazine, issue 7 (1982) pp60-61
NON-TUTORIAL VI
by Charles Bachand
HATS OFF TO ATARI!!

This article contains a graphics program called "Archimedes Spiral". The program, although quite short, takes nearly three hours to run! This is definitely not a quick demo. (To produce the transparent version of the spiral, delete line 240.)(It still looks like a hat to me. Ed.)

100 REM ARCHIMEDES SPIRAL
110 REM 
120 REM ANALOG MAGAZINE
130 REM 
140 GRAPHICS 8+16:SETCOLOR 2,0,0
150 XP=144:XR=4.71238905:XF=XR/XP
160 FOR ZI=-64 TO 64
170 ZT=ZI*2.25:ZS=ZT*ZT
180 XL=INT(SQR(20736-ZS)+0.5)
190 FOR XI=0-XL TO XL
200 XT=SQR(XI*XI+ZS)*XF
210 YY=(SIN(XT)+SIN(XT*3)*0.4)*56
220 X1=XI+ZI+160:Y1=90-YY+ZI
230 TRAP 250:COLOR 1:PLOT X1,Y1
240 COLOR 0:PLOT X1,Y1+1:DRAWTO X1,191
250 NEXT XI:NEXT ZI
260 GOTO 260

It would be so much simpler if you could hand out a hardcopy of the graphics to demonstrate your prowess with the computer. Your friends will be doing cartwheels and going hazoo-huzzah over your printing expertise. (Hazoo-huzzah?! Ed.)

(Ed. Note: No one here at A.N.A.L.O.G is responsihle for Charlie's state of mind when he writes these non-tutorials. Just thought you people would like to know.)


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