- The brain of the PC is processor or CPU.
- It performs the system’s calculating and processing Operations.
- The term N-bits means that its ALU, internal registers and most of its instructions are designed to work with N-bit binary words.
- The major components of CPU are:
- 64-bit processors have 64-bit ALUs, 64-bit registers, and 64-bit buses.
- A 64-bit register can address up to 264 bytes of logical address.
- 64-bit processors have been with us since 1992.
- Eg: 64-bit AMD processor.
- The internal logic design of microprocessor which determines how and when various operations are
- The various function performed by the microprocessor can be classified as:
- Microprocessor initiated operations
- Internal operations
- Peripheral operations
- Microprocessor initiated operations mainly deal with memory and I/O read and write
- Internal operations determines how and what operations can be performed with the The operations include:
- performing arithmetic and logical operations
- test for conditions
- store in the stack
- External initiated operations are initiated by the external devices to perform special operations like reset, interrupt, ready,
- The block diagram of 64-bit microprocessor is shown
- The major parts of the block diagram are:
- General register unit
- Control and decoding unit
- Bus unit
- Cache memory unit
- Floating point register unit
- Issue ports
Fig: Block diagram of 64-bit internal architecture
- Addressing Modes
- General Purpose Registers
- Non-modal and modal Instructions
- New Instructions in Support of 64-bit
- New immediate Instructions
- This addressing mode determines the working i.e 24,32 or 64 bit mode
- PSW bits 31 and 32 designate addressing mode (out of 64 bit).
o Addressing modes bits:00=24 bit-mode
General purposes register (GPR)
- The register is treated as 64-bits for:
o Address generation in 64-bit mode.
- The register is treated as 32-bits for:
o Address generation in 24/32-bit mode.
New instructions in 64-bit:
- Load Reversed - LRV, LRVR
- Multiply Logical - ML, MLR
- Divide Logical - DL, DLR
- Add Logical w/ Carry - ALC
- Subtract Logical w/ Borrow - SLB
- Store Reversed - STRV
- Rotate Left Single Logical – RLL
New immediate Instructions
- Load Logical Immediate
- Insert Logical Immediate
- AND Immediate
- OR Immediate
- Test Under Mask (High/Low)
Comparison of 64-bit with 32-bit
- Contains 32-bit data lines whereas 64-bit contains 64 data lines.
- Can address max 2^32(4 GB) of data whereas 64 bit can address 2^64(18 billion GB).
- Speed and execution is both fast in 64-bit processors.
- 64-bit processors can drive 32-bit applications even faster, by handling more data per clock cycle than a 32-bit processor.
- The table shows the basic difference between two: