September 1992 MAGazine Volume 8 Number 9

Table Of Contents


Winners of the August Animation Contest were Mike Wallace for freehand rendering and Don Morgan for the still life competition. We wish to thank all who entered and look forward to more events in the future. There will be a complete listing of all winners in this summers competitions.

From the President's CLI

By Brian Akey

Hello all, This is your trusty president, Brian. As you may or may not know, I will not be able to attend this months meeting as I will be attending a friends weeding in another city. I would like to thank all who entered the Graphics competitions and congratulate those who won! Enjoy the meeting and I will see ya next month.

Digital Creations Releases RGB Converter

An overview of the DCTV RGB Converter:

What does it do:

The RGB Converter takes the composite video signal from the DCTV and inserts it into the stream of RGB data. Any destination device such as a genlock, monitor or encoder will then have access to the DCTV composite image contained in the RGB stream. Although the image is in the RGB stream, it is still a composite DCTV image. It will not change a pixel-based image but will retain the smooth look of composite video.

How and where is it connected?

The RGB Converter, for use with DCTV, is a small external device that plugs into the RGB stream between the DCTV and the RGB monitor. When used with an external genlock (like Digital Creations' SuperGen) it goes between the DCTV unit and the genlock.

What can be done with a DCTV, and RGB Converter, and an RGB monitor?

The main effect of using these three components together is that the DCTV output will behave like a normal Amiga graphics mode. For example, while painting in DCTV (on the RGB monitor) you decide that you need to change to a different font directory. You put the DCTV screen to the back and Workbench appears on the same monitor that you were just painting on. You do the font assignment and decide to take a peek at your painting. Using the mouse pointer on the drag bar of Workbench you pull the front screen down and reveal your DCTV image in full color. The top half of the screen is DCTV and the bottom half is standard Amiga RGB. Or you could make a slide show that contained a mixture of DCTV images in normal Amiga modes.

Does the RGB Converter eliminate the need for a composite monitor?

To some extent it will. However a composite video monitor will still be needed for the video preview mode when digitizing.

From the Editor,

Hello, I am Trevor Thrasher and I am the new Editor. After a week or so of consideration, and much proding from others, I decided to take on this task. This is my first attempt at compiling a complete newsletter and I hope it is not obvious.

In future editions I hope to add more articles and work by MAG members, this is your magazine! So if you have anything you would like to add (questions, comments, letters or what ever) get in touch with me. This can be done by either calling me or leaving me email on any of the local Amiga Bullentin Boards or in the near future on VideoSpeak BBS, the official MAG BBS. (853-4804) My handle is Visual Mark.

I would like to thank all that have contributed and helped in getting this together. Also I would like to say that this newsletter was done using an Amiga 3000 and PageStream 2.2. Look for an even better edition next month and remember, let me hear from you. Until next month enjoy! PEACE.

MAG .info


Brian Akey (901) 278-6354
Vice President
Donnie Webb (901) 363-8025
Raymond Ginn (901) 353-4505
Micheal Cervetti (901) 386-2584
Ken Winfield (901) 382-3339
MAG Editor
Trevor Thrasher (901) 323-4476
Terry Campbell (601) 393-4864

Dues Notice

Dues must be paid at or before the General Meeting of your expire date. If paid on or before this time, the renewal rate is $20 for the entire year. If you wait past the general meeting you will be dropped and must renew at the new member rate of $25 for the year. Please pay at the General meeting or send dues to:

MAG dues c/o Michael Cervetti
8300 Rembrook
Cordova, TN 38018


The Memphis Amiga Users Group holds general meetings the second Saturday of each month in the Farris Auditorium on the campus of State Technical Institute at Memphis For more information call Brian Akey at (901)377-1093.


A variety of Amiga specific videotapes are available from the Club's library for $3.00 a week. Video digitizer and other Hardware items are also available. For more information contact Ken Winfield at (901)382-3339.

Disk Sales

MAG library and Fred Fish disks are $2.00 each. High Quality Blank disks with labels are 65 cents each. These items can be purchased at each general meeting.


(free for Members)

1 meg Agnus $35, Redman 2000 Adaptor for A1000 $10 (new) A1000 without keyboard $100 will trade for video hard-software contact Jim 454-0005

Games for sale Keef the Thief $7 WindWalker $7 Dragon's Lair $15 Police Quest I & II $20 each Hero's Quest $20 Will consider best off contact Julia Dye 755-7331

Financial Report

Beginning balance $943.66
Income 65.00 Dues
89.00 Disks
$154.00 Total
Ending Balance $899.66
Expenses 96.00
Gen-lock 26.00
Rom disk 29.00
Magazine 49.00
FredFish 7.00
Total 198.00


Please help me keep the Magazine accurate by contacting the editor on any incorrect information contained in this printing. If you would like to place an ad in the Magazine please contact the editor Trevor Trasher (901) 323-4776


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Tyranosaurus AREXX

by Kevin-Neil Klop

Variables. It conjures up visions of high school algebra and mathmatics. It has been known to make strong people cry and weaker people slit their mental wrists. Nightmares of X's, Y's, and Z's parade through one's head carrying sharp pointed objects much like the end scene to Frankenstein. And you're the monster.

Ooooooo, scary.

Well, it's not all that bad. We're not going to make you solve for X, isolate Y, or substitute Z. In fact, there are quite a number of situations in programming where variables use no math whatsoever.

If I pointed to a cardboard container and said, 'Box,' you wouldn't start feel anxious or worried, would you? Well, a variable in computer-speak is much the same as a cardboard carton. It's there to contain other things that you don't want to have laying about at the moment.

Here's an example:

X = 1
Y = 2
Z = X + Y

This is NOT math - at least it's not when it's written in an Arexx script. Think of this as commands that create 3 containers, labelled 'X','Y', and 'Z'. I could just as easily have called them 'Kitchen', 'Livingroom,' and 'Bedroom'. I put the number 1 into the box marked 'X', and the number '2' into the box with the 'Y' written on it. Then, I took the '1' from the 'X' box, added it to the contents of the Y box, and put the result into the box marked 'Z'. Note, however, that the X box still contains that 1, and the Y box still contains the '2'; the Z box now contains a '3'.

That wasn't so bad, now was it? Of course, things CAN get complicated. For example:

alice = 'doesn't live'
where = 'here anymore'
book = alice || ' ' || where

In this case, there are three boxes marked 'alice', 'where', and 'book' Into the 'alice' box we put the WORDS 'doesn't live'. Into the box 'where' we put the WORDS 'here anymore' and into 'book' we put some strange mix of what's in 'alice', some vertical lines, two single quotes separated by a space, some more vertical lines, and then what's in the box 'where'.

Let's think about things for a moment. With numbers we can add, subtract, multiply, divide, and do linear regression analysis. Well, okay. SOME people can do linear regression analysis. I can't.

But what can you do with words? You can't add them; what's 'ambercrombie' plus 'holistic'?? You can't subtract, divide, or multiply then, and NOBODY can do a linear regression on words! What you can do, though, is string them together, break them apart, or look at the letters in them. Programmers have come up with new symbols to incicate these kinds of operations. For instance, the symbol '+' in mathmematics means 'add'. With words, the symbol '||' means 'join these things together'.

If you recall last month's lesson, surrounding something with single quotes means 'Take what's between the quotes exactly as written'. With that in mind, let's see what we put in the 'book' box. First we took the contents of the 'alice' box, made a copy of it, and put the original back into 'alice'. Next, we took a space (surrounded by quotes, so ARexx wouldn't ignore it) and pushed it up against what we got from the photocopier. Finally, we copied the contents of the box marked 'where' and pushed that up against the contents of 'alice' followed by the space, and put the result into the box marked 'book'. Let's write that as an ARexx program:

/* ALICE program */
alice = 'doesn't live'
say alice
where = 'here anymore'
say where
book = alice || ' ' || where
say book

and out comes the words 'doesn't live here anymore'. Don't forget the comment at the beginning of the program or it will NOT work. Those of you who have been watching VERY closely will notice a few things that may seem a little strange.

  1. Sometimes I surround things with double quotes (") and sometimes I surround things with single quotes (')
  2. Last issue I said that there had to be an even number of single quotes and an even number of odd quotes, and yet what I put into the 'alice' box contained an ODD number of single quotes.

As to strange thing number one, you're right. In general, it doesn't matter whether you use single or double quotes as long as you match them up. Except when you have an imbedded quote, like in strange thing 2. Strange thing number 2 occurs for a variety of reasons. In this case, we had a contraction - a word containing a single quote. Because the single quote is INSIDE of a double quote, ARexx ignores the 'rules' until it sees a second double quote. Thus the following lines are not the same:

/* Arexx Quoting/Comment example 1 */
Strangeness = /* Obla dee obla da live goes on, la! */ 'La la
    la la la goes on!'

/* ARexx Quoting/Comment example 2 */
Strangeness = '/* Obla dee obla da life goes on, la! */ 'La la
    la la la goes on!'

In the first example, the box marked 'strangeness' would contain the words 'La la la la la goes on!' In the second example, the box would contain the words '/* Obla dee obla da live goes on, la! */ 'La la la la la goes on!' This is because in the first version, '/* Obla dee obla da life goes on la! */' is a comment and ignored by ARexx because it's not inside the quotes. In the second version, it IS inside the quotes and is NOT treated as a comment.

You might want to play around a bit with variables for next issue. If you have any questions, you can ask them through the ARexx topics in the StarShip bulletin board on GEnie. If you are reading this through a posting on some other bulletin board, you can write to me at:

Kevin-Neil Klop
c/o Syntactics
3188 E. Mercer St
Philadelphia, PA, 19134

Virtual Reality

Imagine a total body movement sensor suit and wraparound sterovision goggles allowing us to fly slowly just above the trees while a fan blows us with air and stero bird sounds ring in our ears.

Is that possible now?

Sure, why not? The Amiga currently uses software that will allow for a 3D raytrace steroscopic animation sent single fram to Videotape. The use of two in-sync videotape recorders and color goggle monitors would create the illusion of true 3D space. Sound is the next stp and the Amiga could sync sound effects to each frame of the moving video. Final control would be the movement of sensored regions of the user to effect the outcome of the video as it played in real time. Real time is the last and hardest step to the virtual world programmer. Sure a videotape animation would be a good start to sensing the "world", but the only way to have real time control is to have an active program that would create rendering changes on the fly, thus very fast computing (raytraceing) or controlling stored images would be required. With the first lowcost systems for stereo 3D realities coming out in the next few years, space blast games with lots of visual perspective will be all the rage and warnings for limited use due to eye fatige and dizzyness will be the news media sound bytes for the day.

With today's technology, even the fastest supercomputers have trouble keeping up in a real-time 3D environment such as would be necessary for true Virtual Reality. Speed of computation and cost are directly proportional, and as of yet there is no low-cost method of achieving quality Virtual reality due to this constraint. That fact is what makes the Amiga computer so very well suited to such a use. The basic architecture of the operating system as a true multi-tasking environment allows the Amiga to take full advantage of its clock speed and storage resources. For the unitiated, the Amiga makes use of a special set of custom chips which handle all of the complex tasks. The central processing unit acts as supervisor and simply assigns tasks to the custom chip set while handling error conditions. As a result of this setup, while the Graphics chips are displaying the last rendered scene and the sound chips are playing sampled sound, or while the Input/Output chips are handling communications or playing MIDI instruments, the math chips are concurrently calculating the next videoframe or doing calculations for some other programs.

What this translates to is an action/reaction system. The CPU can tell the input chips to monitor all input devics for instructions. While instructions are received, the CPU tells the sound and graphics chips what changes have been made in the input environment, and the responses are promptly incorporated into the machine's output. With the right programming and a bit of hardware upgrading, even a base Amiga 500 can become a grand Virtual Reality laboratory. Virtual reality is on it's way and soon dreams might have slots for credit card holders.

written by Neuron God & Suedoe


1. Akey Brian L. Memphis TN 38107 OCT 93
2. Andrews Freddie L. Memphis TN 38128 JAN 93
3. Bilson Edward Memphis TN 38115 JAN 93
4. Bowers William Memphis TN 38118 MAY 93
→ 5. Browne Kevin Memphis TN 38111 SEP 92
6. Burns Keith Cordova TN 38018 NOV 92
7. Campbell Terry A. Hora Lake MS 38637 DEC 93
8. Carruthers Joey Memphis TN 38119 FEB 93
9. Cervetti Michael Cordova TN 38018 AUG 93
→ 10. Chiego John & Sara Memphis TN 38119 OCT 92
11. Crighton Robert, Jr. Millington TN 38053 APR 93
→ 12. Dahms Michael K. Memphis TN 38127 OCT 92
→ 13. Deschamps Joe Jackson TN 38305 SEP 92
14. Dobbins Chris Memphis TN 38152 APR 93
15. Dobson Michael Memphis TN 38118 NOV 92
16. Durfee Tony Jackson TN 38305 DEC 92
17. Dye Julia Ann Memphis TN 38120 APR 93
18. Echols Steve Memphis TN 38125 DEC 92
19. Evans Larry Memphis TN 38135 JAN 93
20. Fanelli Daniel R. Germantown TN 38139 FEB 93
21. Franklin Shelley Memphis TN 38120 MAR 93
22. Ginn Raymond Memphis TN 38127 APR 93
23. Glover Steven Cordova TN 38018 JAN 93
24. Harper Richard Memphis TN 38111 FEB 93
→ 25. Hartley Marilyn Memphis TN 38118 SEP 92
26. Hawkins Conrad G. Memphins TN 38117 JUL 93
27. Hooker Bill Memphis TN 38134 NOV 92
→ 28. Hudson Scott Memphis TN 38141 OCT 92
→ 29. Ingerson Steve Walls MS 38680 SEP 92
30. King Guy Collierville TN 38017 JAN 93
31. Kligel Joseph Memphis TN 38118 APR 93
32. Knight Ronnie Burlison TN 38105 JUN 93
33. Langston Scott Memphis TN 38111 JAN 93
34. Lewis Jeff Memphis TN 38134 MAY 93
35. Lowder Mark Memphis TN 38118 FEB 93
36. McCalla Ron & Audrey Jackson TN 38305 DEC 99
37. Mergen Steve Memphis TN 38104 MAR 93
38. Miller William Germantown TN 38138 JUN 93
→ 39. Mitchell Mike Memphis TN 38108 SEP 92
40. Montgomery Ronald Memphis TN 38108 DEC 92
→ 41. Morgan Yvonne & Charles Memphis TN 38168 SEP 92
42. Morgan Don Memphis TN 38117 JUN 93
43. Mott James Memphis TN 38109 JAN 93
44. Nolen Kent Arlington TN 38002 JUL 93
45. Norman Joe R. Dyersburg TN 38024 JAN 93
46. Nunn Bob Memphis TN 38141 AUG 93
47. Pittman James E. Memphis TN 38116 APR 93
48. Photo Grafix Jim Memphis TN 38112 MAY 93
49. Ralston Bruce Memphis TN 38104 MAR 93
50. Reagan Alan Memphis TN 38104 NOV 92
51. Rush David Memphis TN 38127 NOV 92
52. Sanders Joe Memphis TN 38134 AUG 93
53. Sheridan Larry Brighton TN 38011 NOV 92
54. Spence David E. Collierville TN 38017 MAR 93
55. Stokes Paul Eads TN 38028 DEC 92
56. Swope Henry Braden TN 38010 NOV 92
57. Thrasher Trevor Southaven MS 38671 NOV 92
58. Torrence Samuel Tupelo MS 38801 MAY 93
59. Underwood Lenore Millington TN 38053 DEC 92
60. Varnell Roy Memphis TN 38127 APR 93
61. Vineyard Charles W. Memphis TN 38118 AUG 93
62. Walker Jim Memphis TN 38128 JAN 93
63. Wallace Michael S. Marion AR 72364 AUG 93
64. Walp Len Memphis TN 38128 JAN 93
65. Watson Jerry Memphis TN 38118 NOV 92
66. Weatherall Broadus Memphis TN 38111 JAN 93
67. Webb Donnie Memphis TN 38118 JAN 93
68. Wells Phillip Jackson TN 38301 APR 93
69. Williams Charles Wilson AR 72395 DEC 92
70. Winfield Kenneth Memphis TN 38128 OCT 93
71. Wulff John Memphis TN 38115 JUL 93
72. Wyatt Joel Jackson TN 38301 FEB 93
73. Yates Richard Memphis TN 38134 MAR 93