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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](Multi IO.jpg)
The board consisted of the
following I/O support sections: -
-
Three programmable serial I/O
devices for communicating with data terminal equipment (terminals, printers,
etc.) or data communications equipment (modems, computers, etc.).
-
Three parallel ports (one
input and two outputs) configured to plug directly into the
50 conductor ribbon cable of a Diablo compatible parallel
'Daisy Wheel' printer, and capable of being interfaced to most any
parallel computer peripheral.
-
A real time clock/calendar chip with
provision for battery back-up, and the ability to cause timed interrupts at
selectable intervals for multiprocessing and time-sharing
applications.
-
A programmable interrupt controller
(PIC) capable of resolving eight levels of maskable, prioritized interrupts,
five of which are asserted by the board itself.
-
Four Kbytes of 2716 EPROM's or four
Kbytes of high speed static 6116 Ram (in the same sockets) or two Kbytes of
each. Both Ram and EPROM are bank selectable and able to respond to all 24
S-100 address lines (extended addresses) as defined in the IEEE-696 buss
specification.
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
This page was last modified
on
01/08/2011