Terminal Control; Input/Output Devices; Communications Interfaces - Wyse WY-60 Maintenance Manual

TERMINAL CONTROL
Terminal control components include the 8051 microcontroller
described above and the 2672 programmmable video timing
controller (PVTC). The 2672 controls vertical and horizontal
timing, consecutive addressing for the display memory, the
microcontroller-display buffer interface, and consecutive
addressing of row buffers. The PVCT controller reads displayed
characters and attributes from their respective RAMs on a DMA
basis, sending this information to the gate array. The gate
array generates the video signals that control the display.
Functions of the terminal firmware include keyboard scanning,
programming the video controller, data transfer to and from the
communication ports, and data manipulation.
INPUT/OUTPUT DEVICES
I/O devices consist of a CRT display, two communications
interfaces, and a keyboard.
CRT Display
The terminal has a 14-inch, flat-screen CRT. It displays 26 or
44 rows of characters and 80 or 132 columns. Available phosphor
colors for the CRT include green, amber, and white.
Communications Interfaces
The terminal has two asynchronous serial interfaces that conform
with the EIA standard RS-232C. Data rates are set independently
for both interfaces. These parameters are operator controlled
and are defined in "Setup Parameters" in the User's Guide. The
MODEM interface can communicate at data rates up to 38.4K bits
per second (bps). The AUX interface can communicate at data
rates up to 19.2K bps.
Keyboard
The terminal is available with three keyboards: the WY-60 ASCII
keyboard, an 316X-style keyboard, and an AT-style keyboard. Each
has a standard four-wire interface with the terminal. All keys
are momentary action key switches. The microprocessor
periodically scans the keys, checking for key closures.
Figure 2-2 in Chapter 2 shows the keyboards. You can find
add it ional in fo rm a tion ab out the ke yboard s in Cha pte r 6, "Theo ry
of Operations" and Chapter 7, "Schematics." .
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