Wang 5536 - Basic Workstation Functions; Z80 A Cpu; Diagnostic Memory; Parity Generation and Test

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2.2 BASIC WORKSTATION FUNCTIONS
2.2.1 Z80A CPU
P s operations are controlled by the Z80A Central Processor (CPU). The CPU
receives sequential instructions from Main Memory over the data bus. It
assigns device access and tasks based on these instructions and
communicates with workstation logic through the data, address, and control
busses.
2.2.2 DIAGNOSTIC MEMORY
A diagnostic PROM contains special instructions to facilitate component-
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the 7545 PCA at the repair facility and therefore is not shipped with the
workstation.
2.2.3 PARITY GENERATION AND TEST
The Parity Generator/Tester checks
CPU before it enters the processor.
user through CRT display messages.
2.2.4 IN-OUT DECODERS
the accuracy of all data received by the
Parity errors are communicated to the
Memory instructions IN and OUT instruct the CPU to transfer data into or
out of an I/0 device rather than memory. The IN-OUT decoder identifies the
selected I/O device.
2.2.5 KEYBOARD INTERFACE LOGIC
During an appropriate IN instruction the Keyboard Interface places a
character code onto the Data Bus. The CPU examines the character and
stores it in the CRT memory buffer to be placed on the CRT display.
2.2.6 VIDEO DISPLAY LOGIC
Video Display Logic continuously reads characters from CRT memory, converts
them into an appropriate stream of video dots, and arranges these dots on
the CRT display. Video Display Logic also reads a Control Memory. This
Control Memory indicates the display status of each character: normal,
intensified, underlined, etc.
2.2. 7 DATA LINK
The Data Link permits workstation memory to be loaded (or read) by the
master. The master can wri.te new memory instructions into workstation
memory; it can also record (archive) information entered by the workstation
onto a common disk. The workstation CPU is disabled when the Master uses
the Data Link •. During tb,is time Direct Memory Access (DMA) logic, rather
than the CPU, synchronizes memory read/write operations. DMA logic does
not support CRT memory transfers.
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