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by Russ Bellew · phone 954 873-4695

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My PC History 1 > My PC History 2 > Zilog Z80 > My PC History 3 > My PC History 4 > My PC History 5 > My Faves >  
My (computer) beginnings 
 
Time sharing
 
While working in a product development lab at RF Communications (soon to become a division of Harris Corp) I heard wide-eyed fables of the new Hewlett-Packard minicomputer that another development lab within the company had just received. This was probably about 1969 or '70. Supposedly it could even plot filter curves for the Butterworth and Chebychev filters with which we worked.  I never saw it, though.
 
In 1972, while working in a development lab at Sunair Electronics, I saw my first handheld scientific calculators. The heavy-hitter was the HP-35. A few colleagues bought the HP-35 and the later HP-45 and learned their RPN (reverse Polish notation); they were too expensive for me. I did, though, have access to a time shared computer terminal: a Teletype Model 33 that sat in a corner of the lab.  It talked via a modem and phone line to a commercial time-shared minicomputer. Among other jobs it ran a BASIC interpreter. With it, I could create and run simple programs, most of which analyzed circuit behavior and organized bills of material. Our department stored our few modest programs on punched paper tape. Watching the noisy Teletype machine print out the results of its calculations was intoxicating. I was hooked.  
  
 
KIM-1
 
Late in 1976 I bought my first gadget that could be called a computer: a MOS Technologies KIM-1 (Keyboard Input Monitor). It was a single printed circuit board with an LED display (in hexadecimal), a numeric keypad, an 8-bit 6502 microprocessor (which was internally almost identical to Motorola's much more expensive 6800 CPU), and a few kilobytes of memory. It had a tape interface. I think that it was designed as a development tool and demonstration of what the 6502 could do. I was forced to learn the rudiments of how an 8-bit CPU (central processing unit) works, as well as hexadecimal arithmetic. For such a small thing, it presented me with a steep learning curve.  
 
 
The Commodore PET 2001
 
My next computer, which really could be called a computer, was one of the first Commodore PETs. It contained a 6502 CPU, 8 K of RAM, a small video monitor, a tiny keyboard, a cassette tape drive, a couple interfaces, a BASIC interpreter in ROM, and a metal case(!).  I jumped at it when I first heard about it. I bought mine directly from Commodore in late 1977 or early 1978. (I guess that they hadn't yet set up distribution channels.) When I first switched it on, it booted almost instantly and greeted me with a friendly "READY ?" prompt.  It (like the Teletype time sharing terminal) was intoxicating. I felt instantly at home, even though I didn't know what I was doing.
 
The feature that appealed to me the most was that the PET was self-contained in one attractive all-metal case.  My KIM-1 had been a mess . . . the PET was tidy . .. you could say that it was house-trained.
 
I could run BASIC programs and store them on the PET's cassette tape drive. The tape drive was very slow: I could start the tape drive, get a cup of coffee, and when I returned it would still be loading a program.
 
Since my small business needed an inventory system, I wrote a simple one in BASIC for the PET. It seems laughable now, but part of the sorting process involved hand swapping data cassettes in and out of the drive as needed by the program. It worked, but it was a frustrating mess to use. The fact that the tape reads would frequently fail didn't help.
 
I tried to turbocharge the PET by adding external memory (in an Integrand S-100 box that was almost the size of the PET itself). I used an S-100 interface card that was made by a tiny company that called itself HUH? Electronics. I bought three 8-Kilobyte static RAM S-100 cards from Bill Godbout. His were the cheapest that I could find -- a mere $150 or so apiece. (Dynamic RAM boards were cheaper, but I wasn't sure that I trusted them to be refreshed.) So for 24 Kilobytes of RAM, I paid $450, plus case, etc.  (Compare that to today's memory prices.) They ran fine, but ran hot!
 
Next, I added a Teletype Model 43 terminal, which I used as a printer. It had a serial (RS-232) interface; I hung that off the PET's IEEE-488 port via an IEEE-488 to RS-232 converter box that was made by another small company called NETworks (I think). I added a pair of tractor drives to my Model 43 so that it could pull tractor drive perforated paper through it.
 
I developed a love/hate (mostly hate) relationship with the RS-232 interface: I guess that it worked fine for its intended purpose, but when used otherwise by manufacturers who modified the RS-232 spec, it could be surprisingly tough to troubleshoot. The exact meaning of RS-232 lines would change, and their 0 and 1 voltage levels would change. It was only a prelude to decades of RS-232 entertainment.
 
With the PET and all its ancillary boxes, I had created a kludge . . . and it still lacked reliable data storage and a comfortable keyboard -- which would add two more boxes.
 Reluctantly, I concluded that I'd bet on the wrong horse  . . . er, computer.  It's ironic that though the PET was self-contained, to make it work for me, I needed to add external boxes . . . and I had bought it because it was self-contained!
 
I still think that the PET would have made a fine controller for intrumentation, in a manufacturing or product test setting. It was a natural, since it contained an IEEE-488 interface (also called HPIB: Hewlett Packard Interface Bus and GPIB: General Purpose Interface Bus).  
 
So far, I'd not met anyone who shared my interest in microcomputers.  Soon, computer stores were springing up, so I ventured into one of the first stores in this area . . .