Chapter 6
Memory and Floppy
Drives
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
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)
Dynamic RAM
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
ROM on the Motherboard
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
RAM on the Motherboard
SRAM on a Motherboard
How SRAM Is Used in Different
Memory Caches
How Memory Caching Works
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…
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)
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
Dynamic RAM Technologies
•
Physically housed on:


•

Main differences in the three:

•
SIMMs (single inline memory modules)
DIMMs (dual inline memory modules)
RIMMs (inline memory modules by Rambus, Inc.)

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
Types of RAM Modules
SIMM Technologies
• First used FPM (fast page mode) memory, then
•
EDO (extended data out) memory
Rated by speed, measured in nanoseconds
DIMM Technologies
• Rated by speed and amount of memory they
•
hold
First used EDO or burst EDO (BEDO), then
used synchronous DRAM (SDRAM)
technology
DIMM Technologies
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)
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)
RIMM Technologies
Parity
• Older method of testing integrity of bits stored
in RAM or secondary medium, or bits sent
over a communications device
Error Checking
• Error-correcting code (ECC)

Current method used to detect and correct an error
in a single bit
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
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
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
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
DIMMs
RIMMs
Reading Ads About Memory
Modules
• The number of pins, the speed, the size, and
the type of module are all important
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
Installing a SIMM Module
Installing a DIMM Module
Installing a DIMM Module
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
Floppy Drives
• How data is stored—physically and logically
• How to manage the data
• How to install a floppy disk drive on a PC
Physical Data Storage on a Floppy
Disk
Floppy Drive Subsystem
Physical Data Storage on a Floppy
Disk
• Disk must be formatted (process of marking
tracks and sectors to prepare disk to receive
data)
Physical Data Storage on a Floppy
Disk
• Data is written to and from the disk via a
magnetic read/write head
Physical Data Storage on a Floppy
Disk
Logical Data Storage on a Floppy
Formatting Process for a Floppy
• Creates tracks and sectors
• Creates boot record
• Creates two copies of file allocation table
•
(FAT)
Creates root directory
The Boot Record
The Root Directory Table
The Root Directory Table
Using Commands to Manage a
Floppy Disk
• Format Drive: /S /V:Volumename /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
Options for the Format Command
continued…
Options for the Format Command
Using Windows Explorer to Manage
Floppy Disks
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
Replacing a Floppy Drive
1. Check that computer and other peripherals are
working
2. Turn off computer and remove cover (Figure 6-20)
3. Unplug data cable and power cable from old drive;
unscrew and dismount drive (Figure 6-21)
4. Slide new drive into bay; reconnect data cable and
power cable (Figure 6-22)
5. Turn computer on; check setup; test drive
Replacing a Floppy Drive
Replacing a Floppy Drive
Replacing a Floppy Drive
Requirements
for Adding a New Drive
• Empty bay
• Extra power cable (or “Y” splitter)
• Extra connection on floppy drive data cable
When a Floppy Disk Drive Doesn’t
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
Common Error Messages
• Non-system disk or disk error. Replace and
•
•
strike any key when ready.
No operating system found.
Bad or missing COMMAND.COM
Error in Config.sys line xx
Himem.sys not loaded
Missing or corrupt Himem.sys
Incorrect DOS version
continued…
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:
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