DTACK Grounded

DTACK Grounded was a computer hobbyist newsletter published from July 1981 to September 1985 by Hal W. Hardenberg.[1] Subtitled "The Journal of Simple 68000 Systems", the newsletter was dedicated to the proposition that the Motorola 68000 CPU could be used to build simple fast computers. In 1981 this was a revolutionary idea. This was before 68000-based personal computers like the Apple Macintosh, Commodore Amiga, and Atari ST had been created. In 1981 Motorola was marketing the 68000 solely as a CPU for high-end Unix workstations. Hal believed that the 68000 could be used as a simple embedded microprocessor as well, and used the newsletter to explain how to do that.

Editor Hal W. Hardenberg

Hal was the editor of the newsletter and wrote almost all of its content. The ostensible purpose of the newsletter was to promote Hal's company's line of 68000-based hardware and software. However, Hal never let that get in the way of telling a good story or explaining how to design or build a fast computer. He was a hardware engineer and a businessman who also knew how to write software. His newsletter was full of amusing and educational stories about the way the personal computer hardware business worked, and strong opinions about the best way to design personal computer hardware and software.[2]

Meaning of the title

"DTACK" is the name of a pin on the Motorola 68000 CPU that informed the CPU that data was ready to be read from memory. If a system had fast enough memory, this pin could be connected directly to the ground plane (or "grounded") to produce the fastest-possible memory read time.[3]

It stands for "Data Transfer Acknowledge."[4]

The Redlands

In order to discourage photocopying of the newsletter, a portion of the DTACK Grounded newsletter was printed on dark red paper. This made it harder to photocopy those pages. This section of the newsletter was called "the Redlands". It typically contained the assembly source code for high performance math subroutines.

DBASIC

A major topic in later years of the newsletter was the DBASIC interpreter. Hal produced a fast Basic interpreter for the Atari ST computer. It was written in hand-tuned assembly language, and ran very fast compared to other basics. But it was non-standard: it couldn't run Microsoft Basic programs, and it couldn't read or write MS-DOS format floppy disks. Unfortunately, as a result it was not very popular.[5]

DTACK Revisited

In the 1990s Hal revived DTACK Grounded as an occasional column in Dr. Dobb's Journal called DTACK Revisited.[6]

References

  1. ↑ http://www.easy68k.com/paulrsm/dg/ Collection of DTACK Grounded newsletters
  2. ↑ http://www.silentpcreview.com/forums/viewtopic.php?t=48920 Hal W. Hardenberg obituary
  3. ↑ http://www.dadhacker.com/blog/?p=1064 Description of DTACK Grounded from an Atari ST Operating System engineer
  4. ↑ http://cache.freescale.com/files/32bit/doc/ref_manual/MC68000UM.pdf?fpsp=1 68000 User's Manual
  5. ↑ http://www.easy68k.com/paulrsm/dg/dgltr88.htm Hal discusses the failure of DBASIC.
  6. ↑ http://www.ddj.com/architect/184410051 Example column of DTACK Revisited on Dr. Dobb's Journal
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