System Block Diagram - RCA COSMAC Operator's Manual

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CROKIT HARDi4ARE STRUCTURE AND IfJTERFAC
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SYSTEM BLOCK DIAGRAM
Figure 5 shows the broad organization of the Microkit
system. The CPU module interfaces with the control con-
sole through the logic on the CLOCK and CONTROL module
(above it). It interfaces with the memory system (to
its left) via an ADDRESS LATCH module (which forms a
16-bit address from two successive CPU address bytes).
It interfaces with the I/O system (to its right) via
the I/O DECODER module (which enables other I/O modules
under appropriate I/O select conditions).
The BUS SEPARATOR module on the memory side splits the
bidirectional CPU data bus into two unidirectional busses
(memory data IN and OUT). Similarly, the BUS SEPARATOR
on the I/O side performs the same function for the in-
dividual, unidirectional I/O data busses (IN and OUT).
The BYTE I/O module is a generalized, 8-bit parallel
data I/O interface for optional user devices. The
TERMINAL I/O module is specifically designed for a bit-
serial (T.eletype-like) I/O device.
Simplified functional descriptions and block diagrams
of the individual modules follow. Each of these is also
described by a detailed logic diagram which appears in
the Appendix. Thus, we present first, for the general
Microkit user, sufficient information for an understanding
of the broad function of each
modul~with
specific details
(e.g., signal names, assigned pin numbers, internal logic,
etc.) supplied in the Appendix.
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