PC12, also known as PC-12. PC-1200 or PC-12/7, by Artronix was a minicomputer built using TTL74 technology and ferrite memory. Computers were manufactured at the Artronix facility in suburban St. Louis, Missouri.
Four Week Wonder
The earliest version of this computer, originally known as the Four Week Wonder, was designed, built and tested as a class project during a short course in computer architecture at Washington University in the late 1960s. Two prototypes were constructed from DEC logic modules, but subsequently dismantled.
A team at the Washington University Biomedical Computer Laboratory became interested in the Four Week Wonder and developed it into a remote graphics terminal for use in radiation treatment planning. This became known as the Programmed Console, or PC (not to be confused with the IBM PC), and a number of prototypes were built under an NIH grant by Spear Inc. of Waltham, MA. The Spear PC was built into wheeled rack cabinet about as high as a desk, and featured a 1200-baud modem, magnetic card storage, a keyboard, and a 5-inch Tektronix storage display driven by a DAC for each axis. An analog comparator was provided so that the horizontal DAC could be used as an ADC under software control. This was used to digitize inputs from four vernier potentiometers mounted on the keyboard, and from a graphical input device known as the Rho Theta. The PC was also equipped with a plotter so it could produce hard copy graphics.
It soon became apparent that the PC was capable of performing significant calculations on its own. The Washington University School of Medicine developed an external beam radiation treatment planning program which ran entirely on the PC, and other groups developed additional software.
By 1970, Spear was no longer interested in building the PC. Dr. Jerome R. Cox of the Biomedical Computer Laboratory approached Arne Roestel, president of Artronix, to see whether his company would produce a commercial version of the PC. Mr. Roestel agreed, and Ken Krippner designed a TTL74 implementation which was initially known as the PC-1200. Although largely compatible with the Spear prototypes, the PC-1200 differed physically and electrically. For mass storage it had a LINCtape dual unit (see LINC), and magnetic card storage was eliminated. It also used a larger Tektronix 611 storage display, about 10 inch diagonal.
The PC-1200 was succeeded by an improved model, the PC-12/7. While the PC-1200 had a memory cycle time of approximately 1200 nanoseconds, the PC-12/7 was intended to operate at 700 nanoseconds. Memory was expanded from 4k of 12-bit words to a standard of 8k and a maximum of 32K. Eventually, much larger ferrite memories were installed on systems running MUMPS database applications. To speed up programs written in Fortran a separate floating point unit was offered as an option.
Later additions included fixed hard disks of modest capacity, larger removable hard disks, and a dual 8-inch floppy disk.
Early Development at Washington University
Software for the Programmed Console was initially written in machine code or in assembly language with a cross-assembler which ran on the LINC. The Spear PC ran a small native assembler/debugger written by Dirk Brinkman. Both of the assemblers used the LAP6 (see LINC) syntax, where all symbolic names were of the form #1A, where 1 could be replaced by any single digit between 1 and 9 and A by any upper-case letter. This imposed a natural limit of 9 * 26 = 234 symbols, but permitted very efficient symbol resolution in the assembler by a hashing algorithm.
Since Artronix did not have a LINC, they adapted LAP6 to run on the PC-12; this was known as LAP6-PC. Although described as assemblers, LAP6 and LAP6-PC were simple operating systems containing an editor, an assembler, and a file system. LAP6-PC was used to port the original source files for the PC radiation treatment planning application to the PC-12.
Artronix initially believed that very little additional software development would be needed, since major application code already existed. However, it soon became apparent that competitive pressure and customer needs would require ongoing improvement and expansion of the applications. To that end, a more modular operating system, OS/PC, was developed. OS/PC retained most of the concepts of LAP6, but was more modular and extensible. For software development under OS/PC, a symbolic assembler, a relocating linker, and a Fortran compiler were provided.
Artronix also developed a special Fortran dialect known as COMFORT (Commercial Fortran) which featured decimal arithmetic and special formatting operators to construct or de-construct binary files. This was never released as a product, but was used internally for development of various utilities and software tools.
Radiation Treatment Planning
It ran an operating system with support for assembly language and Fortran programming and usually came with end user software for Radiation Treatment Planning (RTP), for use by a radiation therapist or radiation oncologist, and Hospital Patient Records. With extended hardware it became a multiuser system running MUMPS. Latter additions included an 8" floppy disk and hard disk of larger capacity. The PC12 initially controlled the Artronix brain scanner (computed axial tomography), but this was for prototyping. The PC12 was also the core of an ultrasound system and a gamma camera system.
The PC12 was eventually superseded by the "Modulex" system built by Artronix around the 16-bit Lockheed SUE processor, roughly around 1976. The PC12 continued in production, but was phased out over time.
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