Memory and Floppy Drives

1
Chapter 6

• Memory and Floppy Drives

2
You Will Learn

• About the different kinds of physical memory and
  how they work
• How to upgrade and troubleshoot memory
• How floppy drives work and how to support them

3
Physical Memory

• ROM
• Retains its data when PC is turned off
• Stores data on chips socketed or soldered to
  circuit boards
• RAM
• Loses its data when PC is turned off
• Two categories
• Static RAM (SRAM)
• Dynamic RAM (DRAM)

4
Dynamic RAM
5
ROM on the Motherboard

• ROM chips (aka firmware)
• Permanent programs
• EPROM (erasable programmable ROM)
• Programs can be changed
• EEPROM (aka flash ROM chips)
• Programs can be changed

6
ROM on the Motherboard
7
Flash Memory

• Makes it possible to replace programming on a
  chip rather than replace the chip itself
• Acts more like secondary storage does not lose
  its data when power is turned off
• Holds data electronically provides faster data
  access than mechanical device, but more expensive
• Uses EEPROM chips

8
RAM on the Motherboard
9
SRAM on a Motherboard
10
How SRAM Is Used in Different Memory Caches
11
How Memory Caching Works
12
Static RAM Technologies

• Synchronous SRAM
• Requires clock signal to manage or synchronize
  its control signals cache memory can then run in
  step with CPU
• Can be either burst or pipelined burst SRAM
• Burst SRAM
• Data is sent in a two-step process first the
  data address, then a series of data transmissions

continued
13
Static RAM Technologies

• Pipelined burst SRAM
• Uses more clock cycles per transfer than burst
  SRAM without pipelining, but is less expensive
• Asynchronous SRAM
• Does not work in step with CPU clock unable to
  process as much data in one request overall
  slower memory access
• Housed within the processor (new trend)

14
SRAM on the Motherboard

• Current systems generally include all SRAM needed
  for optimum performance
• With older system, might be less expensive to
  replace motherboard than to upgrade cache

15
Dynamic RAM Technologies

• Physically housed on
• SIMMs (single inline memory modules)
• DIMMs (dual inline memory modules)
• RIMMs (inline memory modules by Rambus, Inc.)
• Main differences in the three
• Width of data path that each type of module
  accommodates
• Way the data moves from system bus to module
• Goal is to increase overall throughput while
  retaining accuracy

16
Types of RAM Modules
17

18
SIMM Technologies

• First used FPM (fast page mode) memory, then EDO
  (extended data out) memory
• Rated by speed, measured in nanoseconds

19
DIMM Technologies

• Rated by speed and amount of memory they hold
• First used EDO or burst EDO (BEDO), then used
  synchronous DRAM (SDRAM) technology

20
DIMM Technologies
21
Synchronous DRAM

• Currently most popular memory type
• Rated by system bus speed
• Operated in sync and at same speed as system
  clock
• Comes in three variations
• Regular SDRAM
• DDR SDRAM (SDRAM II) most popular
• SyncLink (SLDRAM)

22
RIMM Technologies

• Used by Direct Rambus DRAM
• Each socket must be filled to maintain continuity
• If not filled, socket must hold a placeholder
  called a C-RIMM (Continuity RIMM)

23
RIMM Technologies
24
Parity

• Older method of testing integrity of bits stored
  in RAM or secondary medium, or bits sent over a
  communications device

25
Error Checking

• Error-correcting code (ECC)
• Current method used to detect and correct an
  error in a single bit

26
Upgrading Memory

• Adding more RAM to the computer
• What to look for when buying memory chips and
  modules
• How much and what kind of memory to buy

27
What to Look for When Buying Memory Chips and
Modules

• Use fastest memory motherboard can support
• Match method of memory detection used by the
  module to what the motherboard expects
• Use memory type recommended by manufacturer
• Match tin leads to tin connectors and gold leads
  to gold connectors to prevent corrosion
• Date stamps on remanufactured and used modules
  should be relatively close together
• Beware re-marked chips

28
How Much and What Kind of Memory to Buy

• Use type, size, density, and speed of memory the
  motherboard supports
• Match memory modules already installed

29
How Much Memory Can Fit on the Motherboard?

• Use right number of SIMMs, DIMMs, or RIMMs with
  right amount of memory on each module to fit
  memory banks on motherboard
• 30-pin SIMMs
• 72-pin SIMMs
• DIMMs
• RIMM modules

30
DIMMs
31
RIMMs
32
Reading Ads About Memory Modules

• The number of pins, the speed, the size, and the
  type of module are all important

33
(No Transcript)
34
Installing Memory

• For most SIMMs, the module slides into the slot
  at an angle
• For DIMM modules, small latches on each side of
  the slot hold module in place
• For RIMM modules, remove the C-RIMM (if present)
  and then insert the RIMM in the slot

35
Installing a SIMM Module
36
Installing a DIMM Module
37
Installing a DIMM Module
38
Troubleshooting Memory

• If computer does not recognize new SIMMs, DIMMs,
  or RIMMs, or memory error messages appear
• If memory errors occur during normal operation,
  and you have not just upgraded memory

39
Floppy Drives

• How data is storedphysically and logically
• How to manage the data
• How to install a floppy disk drive on a PC

40
Physical Data Storage on a Floppy Disk
41
Floppy Drive Subsystem
42
Physical Data Storage on a Floppy Disk

• Disk must be formatted (process of marking tracks
  and sectors to prepare disk to receive data)

43
Physical Data Storage on a Floppy Disk

• Data is written to and from the disk via a
  magnetic read/write head

44
Physical Data Storage on a Floppy Disk
45
Logical Data Storage on a Floppy
46
Formatting Process for a Floppy

• Creates tracks and sectors
• Creates boot record
• Creates two copies of file allocation table (FAT)
• Creates root directory

47
The Boot Record
48
The Root Directory Table
49
The Root Directory Table
50
Using Commands to Manage a Floppy Disk

• Format Drive /S /VVolumename /Q /U /Autotest
• Used to format a disk or hard drive
• /S option makes a drive bootable
• Chkdsk drive /F /V
• Checks drives for errors and repairs them

51
Options for the Format Command
continued
52
Options for the Format Command
53
Using Windows Explorer to Manage Floppy Disks
54
Exchanging and Supporting Floppy Drives

• How to replace the drive
• How to add an additional floppy drive to a
  computer system
• Problems that can occur with a floppy drive and
  its support system

55
Replacing a Floppy Drive

• Check that computer and other peripherals are
  working
• Turn off computer and remove cover (Figure 6-20)
• Unplug data cable and power cable from old drive
  unscrew and dismount drive (Figure 6-21)
• Slide new drive into bay reconnect data cable
  and power cable (Figure 6-22)
• Turn computer on check setup test drive

56
Replacing a Floppy Drive
57
Replacing a Floppy Drive
58
Replacing a Floppy Drive
59
Requirementsfor Adding a New Drive

• Empty bay
• Extra power cable (or Y splitter)
• Extra connection on floppy drive data cable

60
When a Floppy Disk Drive Doesnt Work

• Check physical condition of disk
• Check error messages
• Error messages in 600 range occur when a floppy
  drive does not pass POST test
• Check CMOS settings
• Check cables connected to drive

61
Common Error Messages

• Non-system disk or disk error. Replace and strike
  any key when ready.No operating system found.
• Bad or missing COMMAND.COMError in Config.sys
  line xxHimem.sys not loadedMissing or corrupt
  Himem.sys
• Incorrect DOS version

continued
62
Common Error Messages

• Invalid Drive Specification
• Not ready reading drive A, Abort, Retry, Fail?
• General failure reading drive A, Abort, Retry,
  Fail?
• Track 0 bad, disk not usable
• Write-protect error writing drive A

63
Chapter Summary

• Memory
• Required for a system to work
• Stored on microchips,which are often stored on
  memory modules (SIIMMs, DIMMs, or RIMMs)
• Adding more memory can drastically improve
  performance
• Floppy drives
• Once considered essential, now mainly used for
  troubleshooting a failed boot