Digital Equipment Corporation
pdp-11/23 system

[JPEG image of 11/23]

    Digital Equipment Corporation's pdp-11/23 is a Q-bus based LSI (Large Scale Integration) implementation of the standard pdp-11 architecture.

    This specimen started life off as a voice-response controller for one of my employers. The internal configuration consists of 3 double-height boards and a single quad-height module.

    The three double-height boards are:

    The quad-height board:

    Unfortunately, this machine lacks the memory management unit (a single chip, in this case) required to address anything above the standard limit of 28 kw.

    The M8047 Multifunction Module contains ROM-based boot utilities, functions as the Line Clock, and controls the terminal interface, in this case a C. ITOH CIT-220+. The CPU itself contains ODT in its microcode.

    The RXV-21 attaches to an RX-02 unit which serves as the mass storage for this system.

    The machine lives in a pdp-11/03 housing (19" wide, 3 1/2" high, 15" deep) and represents the fastest -11 in the collection, and certainly the one that draws the least power. I imagine the original CPU board was indeed an 11/03 that was upgraded to a /23 later in life by a board swap.

    For those who enjoy the control that only a good front panel can offer, disappointment awaits; there are but 3 switches (Power, Run/Halt, and LTC Enable/Disable) and 2 LEDs (Power and Run).

    The terminal sitting atop the 11/23 is not a VT-220, but rather a "clone" of this venerable device known as a CIT-220+ manufactured by the C. Itoh Electronics Company.

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Last Modified: Sat Dec 21 11:44:03 EST 1996