Wang 5536 - Teleconununications Option

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In addition to the control-output lines, there are three CPU control-in)Jut
lines:
o BUSRQ -- Bus Request. Becomes active when an outside device requests
bus access. BUSRQ input causes the CPU to switch its address, data, and
status lines into a high-impedance state to accommodate the outside
device.
o BUSAK -- Bus Acknowledge. Becomes active to indicate that the CPU has
complied with a BUSRQ.
o WAIT Becomes active to request the CPU to extend the current
memory-access or I/O cycle as long as it (the WAIT) is present. It is
employed in this workstation to synchronize CPU and CRT logic during
data transfers.
2.3.1.11 CPU Interrupts
The Workstation employs one interrupt mode, mode O, which is both hardware
and software selected. At power-up, both the CPU and the external hardware
are set for mode 0 type interrupts. When an interrupt is generated in this
mode the CPU is res tarted to address 0000 HEX. If the Telecommunication
option is not present the only interrupt is due to keystrokes. If the
Telecommunications option is present an interrupt may also be generated by:
o 10 ms timer
o TXRDY (Transmitter ready)
o RXRDY (Receiver ready)
The CPU is forced to address 0000 HEX uhen any interrupt is generated.
When the Teleconununications option is present, interrupt priority is
selected by software.
CPU interrupts must be re-enabled after each interrupt so that further
interrupts can be accepted,
The CPU employs two interrupt inputs:
o NMI -- Non-Maskable Interrupt. An NMI is an unconditional entrance to
the program.
o INT -- Interrupt. INT is the input signal for all other interrupting
devices in the system that are under software control.
2.3.2 210-7544/7744 PCA
The 210-7544/ 7744 PCA con ta ins MAIN MEMORY, DATA LINK and DMA CONTROL, as
well as a DIAGNOSTIC PROM.
2.3.2.1 Workstation Memory (Figure 2-7)
Workstation memory is configured in three categories:
Ma in Memory, CRT
Memory, and PROM (Diagnostic) Memory.
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