Micros Home Up Contents Links RWebs.Net

Back Next

Front Cover
The IMSAI 8080


Rack Mount RM

This hardware lets you mount the computer chassis in a standard 19-inch electronics rack. It consists of side panels that bolt to the inner sides of the cabinet and support the chassis. A special dust cover is provided in place of the standard dust cover, as well as a modified front panel sheet metal escutcheon. This option must be ordered in conjunction with the basic computer system.

22-Slot Mother Board EXP-22

Twenty-two-slot Mother Board replaces all other Mother Board sections in the computer, offering maximum expansion capability. Reduced price available if ordered with basic system. Edge connectors must be ordered separately.

4-Slot Mother Board Expander EXP-4

Four-slot Mother Board Expander to increase the number of available ~lots beyond the six-slot board in the basic system. Bus lines must be wire-jumpered and soldered to existing Mother Board sections. Computer will accommodate up to four EXP-4 boards. Edge connectors must be ordered separately.

Edge Connector EXPM

Connects a pc board in the computer to the Mother Board. Consists of a 100-pin edge connector to be soldered to Mother Board, plus two card-edge guides that attach to side of the card cage. Extra edge connectors may be ordered with the basic system to permit easy future expansion.

Priority Interrupt/Interval Clock Board PIC-8

The PIC-8 board lets your processor perform jobs between interrupts, without the need to continually poll devices to see if any require service.

Priority interrupt logic on this board monitors the eight priority interrupt lines on the computer Mother Board. It can service either single or multiple interrupt requests. When enabled and it receives an interrupt request, the PIC-8 determines if the request priority is higher than the software-controlled present priority and, if it is, issues a restart instruction that directs the system to the appropriate one of eight priority-controlled restart locations.

For multiple interrupt requests, the PIC-8 determines the highest-priority request and processes it normally.

Note that the system does not store inactive requests, and that a peripheral device must hold its interrupt request until it is acknowledged by the microprocessor.

The present-priority status register may be set by software to any desired value to prevent generation of low-priority interrupts until the register is reset to a lower value. The status register may be set to permit all levels of interrupt to occur.

The PIC-8 board also includes a clock circuit which generates program-controlled interrupts at intervals preset from 0.1 millisecond to 1 second. Any three rates may be jumper-selected, selecting from rates of 0.1, 0.2, 1.0, 2.0, 10, 20, 100, 200 or 1000 milliseconds. Any one of the three selected rates, or none, may be selected by the program.

One bit of the DATA OUTPUT port is connected to a transistor and jumper pads to provide a special-purpose program-controlled output. The circuit board also provides five 16-pin DIP hole patterns with power and ground decoupling for special circuits of your own design. Hole patterns are drilled for wire-wrap sockets. There is room on the board to mount a small speaker driven by the aforementioned transistor or other circuits of your own design.

An edge connector EXPM is required to install the PIC-8 board.

General Purpose Prototype Board GP-88

This board may be used to develop and build your own custom circuits. It offers space for up to 31 16-pin DIP devices and two 40-pin DIP's. Or three 24-pin DIP's may be installed in the two 40-pin spaces. Hole patterns are drilled for wire-wrap sockets.

The board is supplied with an onboard regulator and tantalum decoupling capacitor. An edge connector EXPM is required to install the board.

Extender Board EXT

The Extender Board plugs into an edge connector on the Mother Board and is used to extend a functional circuit board out of the card cage for access to circuits. End pins are marked at every fifth pin for fast identification.

Using the Extender Board, the front panel/control board may be attached to any slot in the chassis. Requires edge connector EXPM.

Cooling Fan FM

Muffin-type fan that may be installed at rear of computer chassis. It is recommended when there are 10 or more boards in the chassis.

Front Panel CP-A

The standard front panel and control card. Requires edge connector EXPM.

Power Supply PS-28

The standard IMSAI 8080 power supply providing 28 amperes at +7V dc minimum, and 3 amperes each at +15.8V and -15.8V minimum. Operates from 120V, 50-60 Hz power.

Dust Cover DC

The standard IMSAI dust covet normally delivered with the IMSAI 8080 computer.

Microprocessor Board MPU-A

This is the Microprocessor Board that is part of the basic computer. Requires edge connector EXPM.

Back Micros Home Next

When PCs Were Micros - Bits and pieces of history about the "good" old days of microcomputers
Everything not otherwise is Copyright 1999-2003 by Randy Wilson
Comments? Contact me at micros@rwebs.net