Just a place to store some titbits that are often needed when fixing PC’s, especially older PC’s. I’ll try put the older stuff at the bottom. Also great for writing online PC technician test’s because they are often outdated.
Acronym’s
EEPROM - Electrically Erasable Programmable Read Only Memory
DIMM - Dual In-line Memory Module
SO-DIMM - Small Outline Dual In-line Memory Module (for notebooks/laptops)
SIMM - Single In-line Memory Module
SRAM - Static Random Access Memory – Uses transistors and doesn’t need refreshing
DRAM - Dynamic Random Access Memory – Uses capacitors and needs to be refreshed
The advantage of DRAM is its structural simplicity: only one transistor and a capacitor are required per bit, compared to four transistors in SRAM. This allows DRAM to reach very high density. Unlike flash memory, it is volatile memory (cf. non-volatile memory), since it loses its data when the power supply is removed.
EBCDIC - Extended Binary Coded Decimal Interchange Code
ISA - Industry Standard Architecture
SCSI - Small Computer System Interface
FAT - File Allocation Table
MBR - Master Boot Record
BIOS - Built In Operating System
UART - Universal Asynchronous Receiver/Transmitter
VESA - Video Electronics Standards Association
VLSI - Very Large Scale Integration
IRQ - Interrupt ReQuest or Interrupt Request Line
CPU - Central Processing Unit
More available from AcronymDB
EDO RAM 72 pin 5V
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COMMON HARDWARE NEEDS
LPT1 – IRQ 7 – Parallel Port DB-25 Female at PC DB-25 Male to Printer
LPT2 – IRQ 5
COM1 3F8-3FF IRQ 4 – Serial Port 9pin Male at PC, 9pin Female to Modem or serial device
COM2 2F8-2FF IRQ 3
COM3 3E8-3EF IRQ 4
COM4 2E8-2EF IRQ 3
STANDARD IRQ ASSIGNMENTS
| IRQ | DEVICE USED in AT, 386, 486, and Pentium Computers |
| 0 | System Timer |
| 1 | Keyboard Controller |
| 2 | Tied to IRQs 8-15 |
| 3 | COM 2 |
| 4 | COM 1 |
| 5 | LPT2 or Sound Card |
| 6 | Floppy Diskette Controller |
| 7 | LPT 1 |
| 8 | Real Time Clock |
| 9 | Substitutes for IRQ 2 |
| 10 | Not Assigned |
| 11 | Not Assigned |
| 12 | PS/2 Mouse Port |
| 13 | NPU (Numerical Processing Unit) |
| 14 | Primary Hard Disk Controller |
| 15 | Secondary Hard Disk Controller |
IRQ PRIORITIES
HIGHEST
0
1
2/9
10
11
12
13
14
15
3
4
5
6
7
8
LOWEST
I/O Addresses
| I/O Address | Common Device using Address |
| 130h | Used for SCSI host adapters |
| 140h | Used for SCSI host adapters |
| 170h | Secondary IDE Interface |
| 1F0h | Primary IDE Interface |
| 220h | Typically used for Sound Blaster-type sound cards |
| 240h | An alternate address for sound cards |
| 278h | Assigned to LPT2 or LPT3 and generally used with IRQ 5 |
| 280h | Network Interface cards or the Aria Synthesizer |
| 2A0h | An alternate address for NIC cards or the Aria Synthesizer |
| 2E8h | Assigned to COM 4 and used with IRQ 3 |
| 2F8h | Assigned to COM 2 and used with IRQ 3 |
| 300h | Another Network Interface Card choice |
| 320h | A good place for a Network card, unless there is a SCSI host adapter or MIDI device |
| 330h | A common place for the SCSI host adapters |
| 340h | Another good alternative for the SCSI host adapter |
| 360h | A Network card choice, but beware of the first parallel printer port, this could be a conflict. |
| 378h | The first parallel printer port (LPT 1) in color systems, commonly used with IRQ 7. |
| 3BCh | The first parallel printer port (LPT1) in monochrome systems, beware you may have problem assigning this address to a printer port in Windows 95. |
| 3E8h | Assigned to COM 3 and used with IRQ |
DMA Channels
|
DMA Channel |
Devices commonly assigned |
| 0 | Assigned internal to the system board, you shouldn’t be able to use it. |
| 1 | No specific assignment, although its usually used for sound cards, or SCSI host adapters. |
| 2 | Assigned to the diskette drives. |
| 3 | No specific assignment, although its again a common choice for sound cards, network interface cards, or SCSI host adapters. |
| 4 | No specific assignment |
| 5 | No specific assignment, however Sound Blaster-type cards generally use this DMA channel |
| 6 | No specific assignment |
| 7 | No specific assignment |
| FAT | |||
| Developer | Microsoft | ||
|---|---|---|---|
| Full Name | File Allocation Table | ||
| (12-bit version) | (16-bit version) | (32-bit version) | |
| Introduced | 1980 (Seattle QDOS) | November 1987, (Compaq DOS 3.31) | August 1996 (Windows 95OSR2) |
| Partition identifier | 0×01 (MBR) | 0×04, 0×06, 0x0E (MBR) | 0x0B, 0x0C (MBR) EBD0A0A2-B9E5-4433 -87C0-68B6B72699C7(GPT) |
| Structures | |||
| Directory contents | Table | ||
| File allocation | Linked List | ||
| Bad blocks | Cluster tagging | ||
| Limits | |||
| Max file size | 4 GB minus 1 byte (or volume size if smaller) | ||
| Max clustercount | 4,077 (212-19) | 65,517 (216-19) | 268,435,437 (228-19) |
| Max filename size | 8.3 filename, or 255 UTF-16 characters when usingLFN | ||
| Max volume size | 32 MB | 2 GB 4 GB with 64k clusters (not widely supported) |
2 TB 8 TB (with 32KB sectors) |
| Features | |||
| Dates recorded | Creation, modified, access (accuracy to day only) (Creation time and access date are only available when LFN support is enabled) |
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| Date range | January 1, 1980 - December 31, 2107 | ||
| Date resolution | 2 s | ||
| Forks | Not natively | ||
| Attributes | Read-only, hidden, system, volume label, subdirectory,archive | ||
| Permissions | No | ||
| Transparent compression | Per-volume, Stacker,DoubleSpace, DriveSpace | No | |
| Transparent encryption | Per-volume only with DR-DOS | No | |
CAT5 Cabling uses an RJ-45 connector and can transmit upto 1000MB over less than 10 metres, 100MB beyond that to a maximum distance of 100 metres.
RJ-45 – Registered Jack 45 – primarily ethernet cabling CAT5, also used for??? Max cable length 1000T base is 100 metres.
3.5″ 1.44MB Stiffy Disk (96tpi)
RISC is better than CISC at number crunching – True although less and less so
SCSI Hard drive connector has 50pins (HD50)
BAUD Rate -the number of distinct symbol changes (signaling events) made to the transmission medium per second in a digitally modulated signal or a line code. The baud rate is related to but should not be confused with gross bit rate expressed in bit/s.
How does disk fragmentation occur?
IDE cable 40 pins
Serial ports rely on a special controller chip, the Universal Asynchronous Receiver/Transmitter (UART), to function properly. The UART chip takes the parallel output of the computer’s system bus and transforms it into serial form for transmission through the serial port. In order to function faster, most UART chips have a built-in buffer of anywhere from 16 to 64 kilobytes. This buffer allows the chip to cache data coming in from the system bus while it is processing data going out to the serial port. While most standard serial ports have a maximum transfer rate of 115 Kbps (kilobits per second), high speed serial ports, such as Enhanced Serial Port (ESP) and Super Enhanced Serial Port (Super ESP), can reach data transfer rates of 460 Kbps.vi