IBM Monochrome Display and Parallel
Printer Adapter
This adapter has dual functions. The first
is
to provide the interface to
the IBM Monochrome Display. The second function
is
a parallel
,~interface
for the IBM 80 CPS Matrix Printer.
The monitor interface
is
designed around the Motorola 6845 CRT
Controller module. There are
4K
bytes
of
static memory on the card
which are used for the display buffer. The memory
is
dual ported and
may
be
accessed directly by the CPU.
No
parity
is
provided on the
display buffer. A block diagram of the Monochrome Display function
in on page 2-38.
The characteristics of the design are listed below:
• 80x25 Screen
• Direct Drive Output
• 9x14 Character Box
• 7x9 Character
•
18
Khz Monitor
• Character Attributes
~
The adapter supports 256 character codes.
An
8K
byte character
generator contains the fonts for the character codes. The characters,
values, keystrokes and screen characteristics are tabled in Appendix
C.
Of
Characters, Keystrokes and Color.
Note: This Adapter when used with a display containing P39
Phospor, will not support a light
pen!
Parallel Interface Description
This topic
is
discussed in full on pages 2-65 through page 2-69.
2-37
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