Write down the classification of user visible registers with their functions

There are different types of user visible registers. These are –

(i) General purpose

(ii) Data registers

(iii) Address registers

(iv) Condition codes

(i) General purpose: It can be assigned to a variety of functions by the programmer. Sometimes their use within the instruction set is or trogon to the operation. It can contain the operand for any op code.

(ii) Data registers: Data registers may be used only to hold data and cannot be employed in the calculation of an operand address.

(iii) Address registers: Address registers may themselves be somewhat general purpose or they may be devoted to a particular addressing mode.

Example: Index register, stack pointer.

(iv) Condition codes: Condition codes are bit set by the CPU hardware as the result of operations. Condition code bits are collected into one or more register.