2022-01-13 · 2분
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Accumulator (AC)
- A register that temporarily stores data. Data read from memory and data already loaded in the accumulator perform a specified operation, and the result is loaded back into the accumulator. The accumulator's contents can be cleared entirely to 0, and can be shifted left or right by some number of digits. The accumulator's bit width equals the word length — the number of data bits the CPU can process at once.
Temporary data storage; AC := AC's current value + value read from memory
Program Counter (PC): address of next instruction to execute.
- A register holding the address of the instruction to be executed next. The PC value is incremented by 1 or by the instruction length (in bytes) depending on the word size, executing the instructions stored in memory consecutively. But if a branch instruction is executed, it's updated to that destination address.
Address of the next instruction to execute; interrupts; CPU instruction processing order
Instruction Register (IR)
- A register that holds the instruction currently being executed
Memory Address Register (MAR): address of instruction or data.
- An address register that temporarily holds the contents (address) currently in the PC (program counter) before it is output onto the system address bus, in order to fetch the next instruction to execute
Address bus; PC -> MAR
Memory Buffer Register (MBR): contents of a specific memory address.
(Data bus); the actual contents of MAR (data, instruction); the interface between memory and CPU
Status Register (PSR): execution information
- Indicates the program's execution state and the processor state at each moment a program runs
Data Register (DR)
- Stores the data needed for functional operations.
Address Register (AR)
- Stores a portion of an address needed to compute an address or effective address.
● Base address register
● Index register
● Stack pointer register
User-visible registers: DR, AR
User-invisible registers: AC, PC, IR, MAR, MBR
Original (Korean): tistory — published 2022-01-13, migrated to this blog. This translation was generated with the help of AI.
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