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Morrow - Multi IO Board
This was a very useful S-100 serial and parallel ports IO Board.   It had many features but unfortunately was a little difficult to setup and program.  It did have one neat idea -- instead of taking up many IO ports on the bus you addressed one port that itself addressed other ports locally on the board. With this circuitry some 30 IO ports required only 8 port on the S-100 bus

Morrow Multi IO Board

The  board  consisted  of   the  following   I/O  support  sections: -   
The Multi I/O also provided a power-on-jump option which allowed eight bytes of code to be executed from on-board EPROM memory during system power-on or reset.
The serial, parallel, clock and PIC (Priority Interrupt Controller) devices on the Multi I/O were all I/O mapped - that is, they are accessed through switch selectable I/O port addresses. These devices could be programmed to request an interrupt using the onboard PIC. The 8259-PIC could in turn issue to the CPU up to eight maskable, prioritized interrupt service routine vectors. As the sole system I/O card, one Multi I/O board could be used to support three terminals and a 'Daisy wheel1 printer while furnishing a real time, interrupt driven environment with all interrupt service routines optionally residing in on-board RAM and EPROM. Alternatively, up to four Multi I/O cards could be combined to accommodate as many as twelve terminals with full interrupt support -- good luck programming that!  BTW, I have forgotten what the wire jumper on the right hand side was for.  
The extensive manual for this board can be obtained here


Morrow S-100 Boards
24K RAM   64K RAM    Disk Jockey FDC     Multi I/O    SuperRAM     SwitchBoard    Z80 Board    Hard Disk Controller

DJ-DMA FDC  8K DRAM    HDC-DMA Controller


This page was last modified on 05/04/2016