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general information
1. 2
SYSTEM PURC'1'IORAL DBSCRIP'l'IOR
The WY-SO consists of a microcomputer, a CRT controller, asso-
ciated control logic, and input/output devices.
This circuitry is
mounted on a single printed circuit board located in the display
console pedestal.
All the basic functions are controlled by the
microcomputer.
Timing and control signals for the CRT are gen-
erated on the microcomputer printed circuit board.
The deflec-
tion, high voltage, and power supply circuitry is located on a
single printed circuit card which sits just below the neck of the
CRT.
The microcomputer card and the CRT power supply card are
interconnected by cabling.
Both cards are housed within the
display console.
1.3
MICROCOMPUTER
The heart of the WY-SO is an 8-bit, single component microcomputer
which has 128 bytes of RAM, 32 I/O lines, two 16-bit counter/
timers, a full duplex UART (universal asynchronous receiver/trans-
mitter), and integral interrupt and clock circuitry.
The micro-
computer uses an external EPROM for program storage.
This EPROM
can be either 4K, 8K, or 16K bytes.
In addition to EPROM, a
buffer consisting of up to 4K of RAM is utilized for display
memory.
The microcomputer connects to a bidirectional bus to
which the CRT controller and telecommunications interface elec-
tronics are connected.
These circuits can perform their functions
independently while interfacing with the microcomputer or the
memory on a
DMA
(direct-memory access) or interrupt basis.
1.4
MEMORY
The memory consists of RAM, EPROM, and EAROM.
EPROM is used for
program storage and contains the power-up and self test routines.
The EAROM (electrically alterable read-only memory) is used to
store the operator's setup parameters (such as baud rate and
parity).
RAM is used to store display information which is
repeatedly read out of the memory by the CRT controller to refresh
the CRT screen.
The microcomputer has an address range capability of 64K bytes.
In addition to this addressing range capability, the microcomputer
treats external program storage (EPROM) separately (it has its own
enable line).
This means that external EPROM can consume an
additional 64K bytes of memory space without infringing on the
space available for I/O or RAM.
Figure 1-2 is a memory map for
the WY-SO.
Note that EPROM is not shown, as it does not occupy
I/O or memory address space.
1-2
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