Functional Description.

TM 11-5865-215-13

EL3RJ004

Figure 5-1.

Receiver Control Simplified Block Diagram

The elements of the receiver control communicate via a bidirec-

tional 1/0 bus and 14 unidirectional input and output ports (see

figure 5-2 and FO-5). The I/O bus, as well as the input and output

ports, provide a selectable 4-bit path by which the microprocessor

exchanges data with the following major groups of peripheral elements:

Front panel keyboard scan and lamp illumination circuits.

Front panel analog control conversion and interface circuits.

External unit interface circuits.

The peripheral elements are selected when the microprocessor gener-

ates a 4-bit output control signal (OCO, OC1, OC2, OC3). The OCO

thru OC3 code is accompanied by either an IN strobe, or an OUT strobe.

The IN strobe identifies a microprocessor read (input) operation. The

selected peripheral element responds by feeding data to the micropro-

cessor via the 1/0 bus, or to an assigned input port (depending on

the OCO thru OC3 code). An OUT strobe identifies a microprocessor

write (output) operation. During this operation the microprocessor

sends data, an address, or a command to the peripheral element via

the 1/0 bus or output port selected by the OCO thru OC3 bits.