"...of what use was life to me after a gun had been levelled against me by a human being I adored?"
-from A Gentle Creature by Fyodor Dostoevsky

Hardware Failures on Equipment that is less than 3 years old
IBM Deskstar IC35L020AVER07-0 (20GB), Quantity: More than you could ever dream

AT Modem Commands
ATZ - reset modem
ATH - hang up modem
ATDT# - dial a number (touchtone)
ATA - answer incoming call
ATI3 - identifies the modem

IEEE standards:
IEEE 1394 = FireWire
400Mbps, 63 devices supported

IEEE 1284 = Parallel

USB:
USB1
1.5Mbps/12Mbps, 127 devices supported

USB2
480Mbps

PC Cards
Type I - memory
Type II - NICs, modems
Type III - hard drives

RAM
SIMMs
30-pin, 8-bit
72-pin, 32-bit

DIMMs
168-pin

RIMMs
184-pin

Connectors
9-pin DB = Serial port
15-pin DB (3 rows) = VGA
15-pin DB (2 rows) = Game port/MIDI
25-pin DB = Parallel port, Serial port
6-pin mini-DIN = PS/2
5-pin DIN = AT Keyboard

SCSI
SCSI-1 = 8-bit, 5MBps, 50-pin Centronics
SCSI-2 = 8-bit, 5MBps, 50-pin Micro-D
Wide SCSI = 16-bit, 10MBps, 68-pin Micro-D
Fast SCSI = 8-bit, 10MBps, 50-pin Micro-D
Fast Wide SCSI = 16-bit, 20MBps, 68-pin Micro-D
Ultra SCSI = 8-bit, 20MBps, 50-pin Micro-D
Ultra Wide SCSI (SCSI-3) = 16-bit, 40MBps
Ultra2 = 8-bit, 40MBps
Wide Ultra2 = 16-bit, 80MBps
Ultra3 SCSI (Ultra160) = 16-bit, 160MBps
Ultra320 SCSI = 16-bit, 320MBps

8-bit SCSI supports 7 devices
16-bit SCSI supports 15 devices
The SCSI controller is typically SCSI ID 7 (highest priority)
A SCSI bootable HDD is typically SCSI ID 0
The SCSI bus must be terminated on both ends
Each device must have a unique SCSI ID

Common Troubleshooting
Floppy drive light stuck on - Cable connected backwards
System time not being saved - CMOS battery replacement

COM Ports
COM1 - IRQ 4 - Address 3F8
COM2 - IRQ 3 - Address 2F8
COM3 - IRQ 4 - Address 3E8
COM4 - IRQ 3 - Address 2E8

IRQs
0 - System timer
1 - Keyboard
2 - Cascade to IRQ 9
3 - COM2 and COM4
4 - COM1 and COM3
5 - LPT2
6 - Floppy drive
7 - LPT1
8 - Real time clock
9 - Cascade to IRQ 2 (USB controller)
10 - Available
11 - USB controller
12 - PS/2 Mouse
13 - Math coprocessor
14 - Primary hard drive controller
15 - Secondary hard drive controller