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Unformatted text preview: U is illustrated in Figure 5.7 and the design code is also given in Appendix F. Figure 5.7: ALU Module’s Circuit Design. 5.4-4. DECODER
The CPU core has the 2to4 decoder for the 2-Bit valued signals Rx and Ry,
which are generated by the Control Unit from the decoded 16-Bit instruction. With
the help of 2to4 decoder we can select four different registers with the 2-Bit value of 66 either Rx or Ry. Therefore four registers are selected by the 2-Bits of Rx and next
four registers are selected by the 2-Bits of Ry. Circuit diagram for Decoder is
illustrated in Figure 5.8 and the design code is also given in Appendix F. Figure 5.8: Decoder Module’s circuit representation. 5.4-5. PROGRAM COUNTER
The program counter controls the execution sequence of instructions. After an
instruction is executed, program counter is incremented by one value. When
microprocessor is resetted, the default value of program counter is loaded i.e. zero.
Circuit diagram for Program Counter is illustrated in Figure 5.9 and the design code is
also given in Appendix F.
67 Figure 5.9: Program Counter Module’s Circuit Representation. 5.4-6. M ACHINE CYCLE COUNTER
The Machine Cycle Counter is a simple 2-Bit up counter and provides the
necessary timing for the instruction execution in the control unit. Also we can say that
it counts the number of machine cycles consumed by a single instruction. Circuit
diagram for Machine Cycle Counter is illustrated in Figure 5.10 and the design code
is also given in Appendix F. Figure 5.10: Machine Cycle Counter Module’s Circuit Representation. 68 5.4-7. REGISTER
The Register module is an 8-Bit Verilog construct by which several registers
can be instantiated. The current processor core utilizes six 8-Bit registers but several
others can also be created if required. Registers act as temporary storage for data
under processing. Circuit diagram for Register is illustrated in Figure 5.11 and the
design code is also given in Appendix F. Figure 5.11: Register Module’s...
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This note was uploaded on 01/19/2014 for the course ECE 5101 taught by Professor Sass during the Spring '14 term at UNC Charlotte.
- Spring '14