Give microinstructions for the following register reference instructions of the basic computer

Give microinstructions for the following register reference instructions of the basic computer:

(i) CMA (ii) SPA

In a basic computer, register reference instructions are those that directly operate on registers without memory access. These are executed when the control unit detects an instruction with I = 0 and D7 = 1 (indicating a register reference operation in the instruction decoder).

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Each microinstruction specifies control signals that direct the data flow within the processor.

(i) CMA (Complement Accumulator)

The CMA (Complement Accumulator) instruction takes the current value in the Accumulator (AC) and replaces it with its bitwise complement.

Microinstructions for CMA:

1. AC ← AC' (Complement each bit of AC)

2. SC ← 0 (Reset sequence counter to fetch next instruction)

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(ii) SPA (Skip if AC is Positive)

The SPA (Skip if AC is Positive) instruction checks the sign bit (leftmost bit) of the Accumulator (AC). If the sign bit is 0 (indicating a positive value or zero), it increments the Program Counter (PC) to skip the next instruction.

Microinstructions for SPA:

1. If (AC(15) = 0) then PC ← PC + 1 (Check sign bit and increment PC if positive)

2. SC ← 0 (Reset sequence counter)

   
   

These microinstructions define the control logic needed to execute the given instructions in a basic computer architecture. 🚀