CPU design--organizing basic actions into instructions

By properly organizing the basic actions of the connected device structure, we can accomplish some slightly more complex functions, which are expressed by specific names, which are the instructions we call.

We want to design a data through the instructions given, can complete the arithmetic operation, and can send the result of the operation to the register out of the output of the CPU. Based on the needs of this task, we can design some basic function instructions for the structure of Figure 3-1.

(1) The number of DRAM is taken out to Da;

(2) The number of DRAM is taken out to the out output;

(3) The number of DRAM and the number of DA is added, the result is placed in da;

(4) subtracting the number of DRAM from the number of DA, and putting the result in da;

(5) Multiply the number of DRAM with the number of DA, and the result is in da;

(6) Divide the number of DRAM with the number of DA, and the result is in da;

(7) The contents of Da are sent to DRAM for storage;

(9) The content of Da is sent to out output;

(10) Send the contents of Iram to IR;

(11) The control of the jump data sent to the PC;

(12) A constant is sent to the accumulator da;

......

These directives can be used to accomplish more complex tasks in the future. It is clear that the machine structure restricts the design of the machine instructions. For example, for the structure of Figure 3-1, you want to "send an external data to the accumulator da", such instructions cannot be implemented in the structure of figure 3-1, because it does not have the structure of the input external data.

CPU design--organizing basic actions into instructions