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- 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
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- 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)
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- ROM chips (aka firmware)
- EPROM (erasable programmable ROM)
- EEPROM (aka flash ROM chips)
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- 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
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- 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
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- 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)
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- Current systems generally include all SRAM needed for optimum
performance
- With older system, might be less expensive to replace motherboard than
to upgrade cache
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- 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
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- First used FPM (fast page mode) memory, then EDO (extended data out)
memory
- Rated by speed, measured in nanoseconds
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- Rated by speed and amount of memory they hold
- First used EDO or burst EDO (BEDO), then used synchronous DRAM (SDRAM)
technology
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- 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)
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- 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)
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- Older method of testing integrity of bits stored in RAM or secondary
medium, or bits sent over a communications device
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- Error-correcting code (ECC)
- Current method used to detect and correct an error in a single bit
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- 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
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- 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
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- Use type, size, density, and speed of memory the motherboard supports
- Match memory modules already installed
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- 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
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- The number of pins, the speed, the size, and the type of module are all
important
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- 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
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- 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
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- How data is stored—physically and logically
- How to manage the data
- How to install a floppy disk drive on a PC
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- Disk must be formatted (process of marking tracks and sectors to prepare
disk to receive data)
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- Data is written to and from the disk via a magnetic read/write head
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- Creates tracks and sectors
- Creates boot record
- Creates two copies of file allocation table (FAT)
- Creates root directory
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- 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
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- 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
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- 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
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- Empty bay
- Extra power cable (or “Y” splitter)
- Extra connection on floppy drive data cable
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- 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
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- 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
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- 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:
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- 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
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