Using Computers Of Bits and Bytes What is a bit, what is a byte A bit is a bit, a byte is a word. Bit The smallest unit in the computer system Can be thought of as a switch - either off or on - actually, is magnetic, so magnetized or not (You've heard of magnetic disks) Therefore, has two states (0 - uncharged or 1 - charged) This is referred to as binary Byte (or a word - actually is a character) Is made of 8 bits in series - if had 2 bits, would have 22 states - thus, has 28th power (256) - thats why we have 256 characters at a time from the keyboard Eight is the magic number with computers - referred to as octal Everything is divisable by 8 - as must send characters across the pathways ** Previous material has pertained to all computers (Apple, IBM, Macintosh). Apples are too old - go toss it, pick it up, and toss it again Macintosh are too expensive - can't program them anyway - use programs someone else has written IBM's and compatible are what I know, so... Many Parts to them Called PC's Mostly, are designated by their CPU (386, 486) Intel has a stranglehold now, but will not always - other CPU manufacturs (AMD and Cyrix) Main Processor (Frequently called the CPU) 8086 - original - 8 bit - processed one character at a time - 5 MHz (clock speed) 5000 cycles per second 8088 - 8 bit - 10 MHz 80186 - Edsel (Lemon) 80286 - 16 bit - processed two characters at a time - 10 MHz - 16 MHz 80386 - 32 bit - processed 4 characters at a time - 16 MHz - 40 MHz 80486 - 32 bit - 25 MHz - 33 MHz - clock speeds were similar, but much more efficient (so faster) - also introduced "Overdrives" - doubles the clock speed (25 -> 50, 33 -> 66) - also is a 4X overdrive for the 25 (now 100 MHz) Pentium (Five series - can't copyright a number, can a name) - 64 bit - eight characters at a time - 60, 66, and 100 MHz Bus This is the part of the computer that moves info in and out Connects the monitor, floppy and hard drives, and the chips Amount: Used to be 8-bit (octal) - would move one character at a time - referred to as XT - ran at 8 MHz Went to 16 bit (hexadecimal) - would move two characters at a time - referred to as AT - used an ISA Bus - ISA = Industry Standard Architecture - show how to count in hexadecimal Went to 32 bit - would move 4 characters at at time - 386 DX - also was a 386 SX 386 processor on a 16 bit bus - bottleneck at the CPU - EISA = Extended Industry Standard Architecture - in ISA, bus is 32 bit but the cards still are 16 bit - info travels to a 32 bit bus - bottleneck occurs from the cards - in EISA, card slots are 32 bit - not well received yet Pentium is partially a 64 bit system - not the bus, but certain data paths (RAM, CPU, Cache) Some systems are true 64 bit (ALPHA AXP) - 8 at a time - $6000. Bus Rate: Information moves at a certain speed on the bus Began at 8 MHz for the bus and 5 MHz for the chip (Main Processor) Chips got faster and faster, then a bottleneck occurred with the bus Local-Bus systems were introduced bus speed equalled chip speed - no bottleneck Memory Temporary RAM - Random Access Memory Stays active only when the PC is on Orignials were 64 K - everybody said what are we going to do with all that memory Now is in 10 banks of 64 K, and 640 K Permanent Hard disks Original were 10 MB (actually not 10, but 10240 K, or 10,240,000) Grew to hundreds, now thousands of megabytes (gigabyte is typical) Latest terminology is now terrabyte (1000 gigabytes) Floppy disks 5.25" Original were 90 K (single sided, single density) Went to double sided-double density (360 K) Then, went to DS-HD (1.2 M) Lastly, went obsolete (too flimsey, bulky, damagable) 3.5" Began with DS-DD at 720 K Went to DS-HD at 1.44 M Now have double at 2.88 M Floptical Disks 3.5" disks DO NOT work in standard 3.5" drive, Need Floptical Drive Hold 21 Mb $16. WORM drives Write Once - Read Many Bernouli Drives Allows disk to be removable Drive costs about $400 Disks are 90 or 150 MB Each disk is about $100 Re-Writeable Optical Drives 3.5" and 5.25" 3.5" = 128 Mb 5.25" = 600 and 650 Mb 3.5" = $25 5.25 = $70 Syquest Cartriges Removable Hard Drives 44 and 88 Mb (about $50 - $60) Tape Back-Ups Tapes are smaller than cassettes Common size is 250 Mb $130, and $10 per tape CD-ROM (Compact Disk - Read Only Memory) Can only be read from Put a whole encyclopedia on one disk Disks range from $10 up Single, Double, Triple, and Quad Speed Double speed drives start at $120. Video Cards Input RS-232 signals (vcr, camcorder) Edit and arrange for lessons, presentations $250 - $6000 + Sound Cards Input audio (CD's, DAT's, MIDI output) Do voiceovers for video, programs, etc. $70 - $350 + Fax / Modem Cards Modem allows your computer to talk to other computers Uses serial port - explain serial (portal - one character at a time) Fax part sends documents over the phone lines - can save, print, discard, etc. Run at speeds in multiples of 1200 Current standard is 14.4 K (14,400) $70 + Network Cards Allow computers to share information Different protocols Ethernet Token Ring Software Operating Systems DOS, UNIX, Windows, OS/2, Windows NT, Windows 95 (previously codenamed "Chicago") DOS - Disk Operating System single tasking operating system made by IBM, Microsoft, Digital Research Microsoft has become the standard Version 3.3 or above is the minimum requirement for many systems (3.1, 3.2, 3.3, 4.01, 5.0, 6.0, 6.1, 6.2, 6.22) In the past, needed to learn DOS - not so certain anymore (with Windows NT & 95) Windows (3.0, 3.1, WFW 3.11 - have an old copy of ver 1.0) Runs on top of (in conjunction with) DOS Simulates a multitasking environment - only one thread, not truly multitasking OS/2, UNIX, Windows NT, Windows 95 True multitasking environments UNIX is 64 bit system, the rest are 32 bit