READER'S FIRST ST PROGRAM
Logo spirals, PEEK command
by FRED HATFIELD
When I sat down to read the Wednesday paper, I spotted the long-awaited ad--Atari 520ST In Stock! There it was. I'd spent the previous six months tracking the fortunes of Atari distribution through PR announcements in industry publications and occasional mentions in the staid Wall Street Journal. Jack Tramiel had supposedly sent 520ST's to Europe and Canada, but it was hard to believe that I would finally see the fabled "Jackintosh" in reality.
I lost little time getting on the expressway and driving to a suburban computer store that I'd never been to before. A young salesman greeted me as I entered and ushered me to a table where the 520ST was resting comfortably with a (gasp) dark video screen.
"Where's the display?" I asked anxiously.
"Bad news," was the reply. "The power supply was damaged in shipping, so we can't demonstrate it."
Disappointedly, I glanced through the technical manual. The intriguing illustrations of high-resolution displays only whetted my whetted my appetite some more.
"When will the power supply be replaced?" I demanded. "How soon can I see it in operation?"
"The rep is on the way, but he has a couple of other stops to make first," said the salesman. "And I'm not sure if he'll have a replacement power supply with him."
I could see that I would only frustrate myself further by hanging around. So I left my card and made the salesman swear to phone me as soon as the ST demonsrator was operational.
But I phoned the store the next day, too impatient to wait. The salesman assured me they would have the demonstrator running within a few days. Swell.
I was idly scanning the classifieds when another advertisement jumped out at me---We Have The 520ST. This computer store was completely on the opposite side of town and I had enough sense to call first before jumping into my car.
Yes, they had a number of 520STs in stock and a working demonstrator. After an excited drive, there it was--sitting on a desk with a color display.
The young lady on duty had not been briefed on how to operate the machine. But she didn't object to letting me sit down at the keyboard and start fooling around.
As I groped with the mouse, another customer and his son showed up to watch. From their comments and suggestions, I realized they had somehow gotten a pretty good idea how to operate the GEM graphic desktop.
So I gave up my seat and asked where they got their advance information. It turned out they'd read step-by-step instructions on how to navigate the desktop in the August, 1985 issue of a magazine called Antic.
Careful questioning of the saleslady revealed that she had that particular issue on hand. I immediately acquired that valuable publication. And while I was at it, I figured I might as well go for another $1,000 and I bought a 520ST color system on the spot.
They threw in a box of 3 1/2-inch disks. I rushed home with my purchases, unpacked everything, connected all the cables and powered up. A gorgeous display of Atari fuji symbols and all the colors of the rainbow flashed across the screen.
Soon a bell rang, telling me to move the mouse and place the screen cursor on an OK box. I responded and saw the select light illuminate on the disk drive. The disk was being accessed for information. I could hear the head stepping from track to track and the cursor changed to a... Bumblebee!
Sudddenly I was faced with a strange display on the screen. HORRORS! These were not the neat icons and colors I'd seen at the computer store. I repeated the operation in different sequences, but the results were always the same.
I had to drag myself away for a business appointment. When I got home, I tried again. No better luck. It was now after five, but I dubiously tried phoning the store anyway...
The owner was there. I explained the stopping point and he said, "Come right out, we'll replace it immediately." He remained open to allow me time to drive across town again. When I arrived, he replaced the system, hooked up my new 520ST and exercised it thoroughly.
As a bonus, the September issue of Antic had just arrived with more great information about the ST. That alone would have been worth driving across town for.
Once again I rushed home with all my new loot. Excitedly I connected the cables and carefully turned on the machine. It worked! It was beautiful! Hooray!
WHAT I LEARNED
Despite some predictable minor faults, the user manual is excellent. This is so important for an anxiously awaited machine like the ST. I still remember the first Trash-80s coming with a skimpy two or three pages of documentation until the operating manual arrived by mail.
I had expected that with a single disk drive, making backup disks might follow the much-criticized Macintosh pattern of excessive disk changes. I was pleasantly surprised to find that the display dynamically indicates loading sectors into memory and writing sectors to the new disk. Only two disk swaps! I loved it!
My system came with TOS and Logo disks. BASIC was promised for later. I had trouble getting a program to execute by double-clicking the mouse. This impasse was overcome when I discovered I actually needed to click the File drop-down menu twice--once to open the disk directory and once to open the selected file.
You quickly run up again the limits of the supplied software--an operating system with nothing to operate on and a Logo "sourcebook" that's not enough to get a beginner started programming in this language. However, with some probing and the primitive examples in the booklet, I managed to come up with some minor programs that allowed me to see how the Control Panel and Graphics settings actually work.
As I became more familiar with the drop-down menus and how they affected the display, I became more adventurous. After all, that's what's exciting about computer, isn't it?
The following Logo program draws a spiral pattern in the display area. Try changing the graphics settings for various background colors and line textures.
TO SPIRAL :ANGLE :LENGTH
IF ( :LENGTH > 100 ) [STOP]
SPIRAL :ANGLE :LENGTH + 3
The system will follow your END entry with: SPIRAL defined
To execute, enter at the ?: SPIRAL123 3
You should get an interesting spiral pattern in the graphics area. Due to limited stack size, you will get a dialogue block indicating that you have overrun the stack. But pressing the [RETURN] key displays the pattern.
I always like to be able see what's in memory locations of a computer. I thought there must be a way to get the equivalent of a PEEK function. There is a way--the primitive .EXAMINE will do it, although the display is limited to memory locations between $800 and $77FFF. Try the following:
TO DUMP: START :STOP
IF ( :START >= :STOP ) [STOP]
[MAKE "START :START + 1]
TYPRE .EXAMINE :START TYPE [-]
DUMP :START :STOP
To use, enter DUMP followed by a start address and end the address as shown below: DUMP 491000 491010.
That's it for now. I just hope you're having as much fun with your ST as I am with mine.
Fred Hatfield is a computer systems consultant from New Orleans and his ham radio station is K8VDU. This article arrived at Antic less than a week after the September issue started appearing on newstands.