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Burroughs C7203 Technology

Electronics

Burroughs C7203
Burroughs C7203
The 7203 is built with mid-1970s MOS LSI by AMI, one Motorola LSI IC and Mostek first-generation MOS DRAM.

  • AMI 7513, AMI 7514, AMI 7516, AMI 7517
  • Ai 7401, Ai 7408, Ai 7409, Ai 7439, Ai 7526 (these devices are also by AMI)
  • Motorola 1239-5463
  • Mostek MK4008 - 1k x 1 DRAM

The MK4008 RAM is well enough known, nothing has been discovered to date about the AMI chipset. It is possible that this chipset was produced especially for Burroughs.

There is discrete transistor buffering between the LSI and peripheral devices such as printers and the card reader.

Architecture, Memory & Speed

  • 14 printed digits

  • Internal numeric coding and data paths unknown

  • MOS DRAM, 5x 1k x 1 chips in this machine. The manual states that program memory may be optionally increased from 204 steps to 408 or 816 steps. This machine has five DRAM chips installed and no PCB space for additional RAM, so perhaps the RAM is arranged as:

    • 1k x1 for chipset RAM
    • 1k x1 for first 204 steps (5 bits can encode all of the keyboard, 5 bits x 204 steps = 1020 bits)
    • 1k x1 for additional 204 steps
    • 1k x2 for additional 408 steps

  • ?? kHz master clock, ?? mS memory cycle

Construction

A single double sided board holds the main logic and a series of plug in boards provide buffering for the printer and card reader, and the master clock. The boards are engineered in great detail with reference co-ordinates around the edges and have etched dates between 1972 and 1974.

The power supply is based on a single transformer and has series-pass regulation of output.