Apple Lisa - The IO Board; Input;Output Board Overview; Keyboard Interface

Confidential
Lisa Hardware Reference Manual
7-Jul-81
THE INPUT/OUTPUT BOARD
The Input/Output board contains the circuitry for the I/O devices built
into the Lisa. These devices are:
Keyboard/Clock interface
Two Serial interfaces
Floppy Disk Controller
PIPPIN Hard Disk Controller
Speaker and CVSD interface
The soft-on and soft-contrast registers are also on the I/O board.
I/O devices are accessed through memory-mapped locations in I/O address
space.
THE KEYBOARD INTERFACE
The keyboard interface uses two Control Oriented Processor System
(COPS) microprocessors. The COPS on the keyboard communicates key up
and key down information to the 68000 over a bi-directional serial
interface. The other COPS is on ~he I/O board. It connects the
b1-d1rectional keyboard signal to the 68000 by way of an eight bit
parallel port implemented with a 6522 Versatile Interface Adapter.
Since the same circuitry which is connected to the power-on pushbutton,
the power supply ON Signal, and the power fail signal, also supplies
the clock/calendar function, it is possible for software to cause
the system to turn itself off and on.
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