Microprocessors Chapter 2

External Data Bus Make sure that you read the analogy explaining exactly what the external data bus is binary system - a numbering system using 0’s and 1’s only Binary 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: : 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 place Quick 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 RAM Address 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 Carrier Single Edge Contact Cartridge (SECC) Plastic Pin Grid Array (PPGA)

Voltage Regulators Can convert one voltage of electricity into a lower one Are near a fan because they generate a good deal of heat Thanks to laptops we use these in PCs Necessary to reduce CPU to 3.3 v Voltage set by jumper setting APM 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 speed Jumper 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 CPU Low-end (cheap) SEP (like SEC, but no plastic side) Added 128K cache Problems SEC was proprietary Only ran at 66Mhz, with multiplier Celeron II Same thing, only in PGA form

Duron AMD’s answer to Celeron 200 Mhz bus (2 X 100), faster than 66 Mhz Cheap, therefore popular PGA

Pentium II SEC cartridge Fit 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 II Proprietary to AMD, SEC-type Faster than Celeron (100 Mhz vs 66) Could run 2 calculations per cycle, so effectively ran at Mhz

Pentium III Supports 100/133 Mhz motherboards High-speed L2 cache First 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