Microprocessors

Chapter 2

External Data Bus

Make sure that you read the analogy explaining exactly what the external data bus isbinary system - a numbering system using 0’s and 1’s onlyBinary numbering will be in groups of 8 because 8 bits make a byte How do you read bits, and change binary to

decimals?

Binary System

Example: 10010101 1 : 1 2 : 2 3 : 4 4 : 8 5 : 16 6 : 32 7 : 64 8 : 128

Registers / Clocks

Registers Used as a workplace for problems that you

give the PC

Clocks the maximum number of clock cycles that

your CPU can handle is called the clock speed

a CPU’s clock speed is its maximum speed, not the speed that it will always run at

the system crystal determines the speed at which the CPU will operate

Clocks

The system crystal is a quartz oscillator that is soldered into the motherboard

A CPU can be pushed by a crystal with a lower clock speed that its own, but the CPU will operate at the speed of the crystal

Don’t try to run a CPU faster than its clock speed, or it will overheat and lock up

Underclocking - run a CPU slower that its CS Overclocking - run a CPU faster than its CS

RAM as a spreadsheet

The CPU needs a place to store data, that’s where RAM comes into placeQuick Terminology Chart Any individual 1 or 0 = a bit 4 bits = a nibble 8 bits = a byte 16 bits = a word 32 bits = a double word 64 bits = a paragraph

MCC / Address Bus

Memory Controller Chip (MCC) device that facilitates the flow of data

from RAM to the CPU

Address Bus second set of wires that enables the

CPU to communicate with the MCC

MCC - grabs contents of RAMAddress Bus - controls what it gets

CPU packages

Dual Inline Pin Package (DIPP)Pin Grid Array (PGA) (ZIF)Staggered Pin Grid Array (SPGA)Plastic/Ceramic Quad Flat Pack (PQFP) Used on laptops

Plastic/Ceramic Leaderless Chip CarrierSingle Edge Contact Cartridge (SECC)Plastic Pin Grid Array (PPGA)

Voltage Regulators

Can convert one voltage of electricity into a lower oneAre near a fan because they generate a good deal of heatThanks to laptops we use these in PCsNecessary to reduce CPU to 3.3 vVoltage set by jumper settingAPM also was developed around this time

Cache

Cache - set aside data used in the past in a special, fast storage area enables you to speed up the system

by creating special storage areas for data being moved form the hard rive, RAM, and CPU

Dynamic RAM (DRAM)

RAM of choice in the PC world cheap, small, and relatively fast

Hold capacitors, like batteries, that hold small charges, need to be refreshed considered volatile RAM not as fast as the CPU

Static RAM (SRAM)

SRAM helps get rid of wait states uses a special circuit called a flip-flop,

which gets rid of refresh almost as fast as the fastest CPU very expensive, but doesn’t need to

be refreshed, so uses less effort, PC more efficient

Internal/External Cache

Internal cache small SRAM Cache built in to chip called L1 cache

External cache called L2 cache soldered onto the motherboard in old PC’s mostly integrated into chips since Pentium II

Clock doubling

Running the internals of a CPU at one clock speed, and running the external data bus and address bus at another slower, speed to help CPU makers increase clock

speeds without having to change the motherboards

Pentium

Intel introduced the Pentium processor in 1993 had a 64-bit external data bus that split

internally as 2 dual pipelined 32-bit data buses

dual pipelining - second set of circuitry that enables more than one command to be processed at a time

Pentium

The first 2 Pentium CPU’s, the 60 MHz and 66MHz, needed 5 volts for operation ran very hot

Used clock doubling because motherboards that couldn’t keep up with speedJumper used to set multiplier

Pentium and competitors

The text discusses several different competitors as well as Pentium II & III. You should know why each one was introduced and different cache sizes, speeds, and clock doubling. Take time to read through these.

Celeron

Intel-based CPULow-end (cheap)SEP (like SEC, but no plastic side)Added 128K cacheProblems SEC was proprietary Only ran at 66Mhz, with multiplier

Celeron II Same thing, only in PGA form

Duron

AMD’s answer to Celeron200 Mhz bus (2 X 100), faster than 66 MhzCheap, therefore popularPGA

Pentium II

SEC cartridgeFit into “Slot 1” (Intel)Used MMX technology 57 new commands in instruction set Four new registers

AMD countered with K6 Could support 100 Mhz motherboards Could not fit into Slot 1, so

motherboards had to be created for it

Athlon

AMD’s answer to the Pentium IIProprietary to AMD, SEC-typeFaster than Celeron (100 Mhz vs 66)Could run 2 calculations per cycle, so effectively ran at 200-266 Mhz

Pentium III

Supports 100/133 Mhz motherboardsHigh-speed L2 cacheFirst came in SEC, then in PGA type Less space, cheaper to make

Xeon

Intel-based CPU, slot 1 (SEC)Even bigger caches

Pentium 4

Takes 100 Mhz motherboard and allows four data transfers per cycle, total of 400 Mhz bus (double of Athlon)

Miscellaneous

Slockets Adapters that allow you to place a PGA

CPU in a Socket 1 slot

Overclocking Author discourages it, although it may

work Intel doesn’t guarantee it above certain

speeds More worried about resellers than

ultimate customers