Computers
Central Processor Unit
Basic Computer System
Processor
ALU
CNTL
.....
BUS
Interconnections
I/O module
CONTROLLER
MAIN MEMORY
Memory
BUS
Von Neumann Architecture
 CPU
 Fast
Memory
 Slow Storage
 Binary Program: executed in
sequence
Computer behavior is determined by
stored programs.
John Von Neumann and
ENIAC
Computer Components
Processing (CPU)






Arithmetic Logic Unit
Control Unit
Registers
Word
Clock
Instruction sets
Interconnection


Local bus
Peripheral bus
Primary Storage


RAM/ROM
Cache
Input/Output



Channel
Controller
Buffers
CPU’s
CPU Cycle
Increment Program Counter
Start
FETCH
FETCH
EXECUTE
EXECUTE
Halt
Instruction Format
4 Bits
OP Code
12 Bits
Operands
Instruction:
 Operation Codes
 Operands
Word: set of bits held by registers in the CPU.
May contain instructions or data.
Types of Instructions
Chip Instructions
=
Built-in
Machine Instructions – “microcode”
=
Chip Instructions
+ ROM Instructions
Assembler Instructions
=
Alphabetic Abbreviations for
Machine Instructions
ROM Instructions
INSTRUCTIONS (BIOS in PCs)
ROM
CNTL
ALU
.....
RISC and CISC
CISC uses fewer processor
cycles
RISC has fewer instructions,
requires more processor cycles
How can RISC be faster?
Basic Computer System
Processor
ALU
CNTL
.....
BUS
Interconnections
I/O module
CONTROLLER
MAIN MEMORY
Memory
BUS
Local and Peripheral
Bus
Bus Operation
Transfer Quantity (word)
Address bus
Control bus
Data bus
Speed
Clock speed
Memory Hierarchy
COST
SPEED
REGISTERS
CACHE
MAIN MEMORY
MAGNETIC DISK | DISK CACHE
MAGNETIC TAPE | OPTICAL DISK
Capacity Units
Bit
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte
b
B=8b
KB = 1,000 B
MB = 1,000,000 B
GB = 1,000,000,000 B
TB = 1,000,000,000,000 B
Memory Access Method
Sequential - tape
Direct - floppy or hard disk
Random - internal memory

Dynamic (DRAM)
simple, small, must be refreshed

Static (SRAM)
no refresh needed
Random Access Memory
Chips and chip technology
Flip Flop Circuit Diagram
DASD Access
MAIN MEMORY
CPU
BUFFER
CACHE
DASD
CONTROLLER
Representative Times
Network speed = megabits per second
Disk transfer = megabytes per second
Disk access = milliseconds
Memory access = nanoseconds
Machine cycle =
microseconds/nanoseconds
DASD
(direct access storage device)
Read-Write Heads
Cylinder/Track/Block
Track
Block (Sector)
Cylinder
Data Storage
FAT (File Access Tables), Directories and
Catalogs
Update and Delete
Fragmentation and reorganization
Blocks, Headers and Interblock Gaps
What makes a computer run?
Word size
Instruction set
Bus speed
Main memory
Secondary storage
Buffers and cache
IBM 1107 with tape drives
Operating Systems
PROGRAM
OPERATING SYSTEM
HARDWARE
System Structure Layers
Processor Hardware functions: circuits,
instruction set, procedures, interrupts
Process management: multiprogramming,
management of secondary storage, logical
addressing
External resource management:
communication among process, file
management, device access and addressing,
user support
Virtual Memory
PAGE NUMBER +
OFFSET
PAGE
TABLE
FRAME NUMBER +
OFFSET
PAGE
TABLE
PAGE
TABLE
Pages
Page Frames
Comparison
MVS versions (OS/390)
UNIX
Windows NT
Linux