Robert Uiterwyk's BASIC

This is based on an interview with Robert Uiterwyk in October 2005 by Michael Holley

In mid 1975 Robert Uiterwyk got an IBM 5100 computer for use at his office. The computer came with BASIC and a training course for it. Robert was using it to develop forecasts, occasionally bringing it home to work at night. His12 year old son, Ted, became interested in learning Basic and would ask him to bring it home almost every evening. . In September of 1975, Robert saw an advertisement for the SWTPC computer in Popular Electronics. Being tired of lugging the 50 pound IBM almost every night, he ordered one and received it in November of 1975. He assembled it at night as a Christmas present for Ted, but it did not work. His acquaintances Warren Startup and Bill Blombgren arrived late one evening to track down a solder bridge, and it was running.

He wrote a simple machine language program to print "Merry Christmas Ted" in a loop on a Teletype and put it under the tree. His son's experience with the IBM 5100 left him less than impressed with this simple program. What else can it do, Dad? His son said if it had a text processor he could do homework so Robert wrote a line editor.

In 1976 the idea of writing a simple or tiny BASIC interpreter emerged and was championed by "Dr. Dobbs Journal of Computer Calisthenics & Orthodontia - Running Light Without Overbyte". Dr. Dobbs published the complete source code for these programs that would run as little as 2k bytes of RAM. In addition to publishing the source code they published algorithms and hints on writing your own tiny BASIC.

Inspired by this article, and still waiting for a basic compiler from SWTPC, (who had contracted with someone else to write a BASIC interpreter that never arrived), Robert Uiterwyk decided to write one for Ted's SWTPC 6800. After a month of evenings and weekends he had a working MICRO BASIC. His friends, Bill Blomgren, Bill Turner, Forrest Hurst and Bill Thames were the alpha testers for this version. By May of 1976 MICRO BASIC version 1.3 was done.

The June 1976 issue of the SWTPC newsletter contained the complete source code for the Line Editor and MICRO BASIC 1.3. This was a tiny BASIC, that is it had only integer arithmetic with 26 single letter variables. String variables were not supported.

By then, Robert was working on a 4K, floating point math version of BASIC and was helping his friends start a computer store, Microcomputer Systems, in Tampa Florida. The idea was to sell the SWTPC at the store (and of course, Robert's Basic). Meantime, Robert offered to let SWTPC sell his 4K BASIC for $5 (and latter the 8K version for $10). SWTPC would produce and sell the tapes. Robert would get all of this money, in turn, SWTPC would sell more computer systems.

At the Personal Computing Convention in Atlantic City in August 1976 SWTPC introduced 4K BASIC. They had copies of BASIC on tape ready to sell at the show. The night before the show Jim Stratigos calls Robert to tell him there is a math bug: 1.0 + 0.01 yields 1.1. After an all night debugging session he had a fix. Everyone joins in and they re-record all of the tapes and marked them version 1.1. They sold over 100 tapes at the show. Soon SWTPC is selling both versions.

Pictured above from left to, right are Bill Thames, Rep. of Microcomputer Systems; Steven Uiterwyk, Software Debugger; Robert Uiterwyk, Author 4K BASIC; Gary Kay, SWTPC Engineer; Dan Meyer President of SWTPC; and Joe Deres, SWTPC Engineer. (Photo by Jim Stratigos.)

This was a very capable BASIC interpreter. The math was done in BCD (Binary Coded Decimal) to 9 digits of precision. The number range was 10 E 99. This slowed the calculations but it was more accurate than Altair's 680B BASIC which only had 6 digits of precision. (Altair BASIC could get the wrong answer very fast.)

The 8K version added string variables and trig functions. This BASIC went through several versions including disk versions. (8K Version 2 manual) Robert worked with SWTPC and TSC to sell a multi-user version of BASIC. A special memory board would swap the lower 512 bytes at the task switch interrupt. With BASIC and DOS loaded, 4 users could share 16K of RAM.

Robert also wrote the first floppy disk software for the SWTPC MF 68 mini floppy and helped with the disk controller design along with Warren Startup.

Robert's Basic was sold by other 6800 computer makers including Midwest Scientific Instruments. By January 1978, Robert wanted out of the software support business so sold the source code to Motorola. (He got started in this software effort only to provide a BASIC interpreter for his son.) His BASIC was sold by SWTPC until 1978 when it was replaced by a TSC version.

Interface Age May 1977, Floppy-Rom, Uiterwyk BasicUiterwyk's BASIC was the first software ever published on a "Floppy ROM." The May 1977 issue of Interface Age had a thin plastic record with BASIC in Kansas City standard audio format.

William Blomgren's article described how the record supplier, EVA-TONE  make it work and how to load this record into your 6800 computer. Bill Turner's article provided the User's Guide for Robert Uiterwyk's 4K BASIC.

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This page was last edited April 01, 2015