Memory & Hard Drive Management Chapters 6 & 9 David Turton Conestoga College Institute of Technology & Advanced Learning http://www.conestogac.on.ca/~dturton Doon 1D17 x3610 Early Memory Decisions (DOS) "no-one needs more than 640KB of memory"
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Institute of Technology & Advanced Learning
Doon 1D17 x3610
This is a map of memory addresses
Not physical RAM
Responded to an assigned range of addresses
Responded to a disjoint address rangeDOS Memory Map
PC3200 (400MHz)3.2GB/sec (20x faster)
the more paging you do, the slower you go.
RAM is continually full, continually paging
CPU wasting time, high disk usage, slow response
Page file to another hard drive
On another EIDE cable
Business app score
Mult. applications open
Editing media files
Business: 33% gain
Multimedia: 50% gain
Business: 8% gain
Multimedia: 10% gain
Business: 5% gain
Multimedia: 7% gainVirtual Memory: Problems
This is one reason programs can’t work in “REAL MODE” … Not enough memory for everyone.
“PROTECTED MODE” hides physical limitations, allows O/S to give everyone everything they need.
memory space for application 1
memory space for application 2
Emergency Start-up Disks … Not enough memory for everyone.includes utilities to troubleshoot a failed hard drive… or at least see if you can salvage something … outlook.pst?
FAT16 … Not enough memory for everyone.
255-byte file names
Win 95 SP2
limit ??EBFile Systems (Micro$oft)if the file system is not healthy, cannot use drive
File Allocation Table … Not enough memory for everyone.
1 pointer for each cluster on disk
Points to next cluster for a file
All 1's means end-of-file
All zeros means cluster is free
Else: address of next location
16 bits per pointer
Max value 216 = 65,536
Can only be 65,534 clusters on disk
2GB disk …
2,147,483,648 bytes / 65,534 clusters
= 32,700 bytes/cluster
5-byte file uses 32KB on disk
32 bits per pointer
= 4.2 billion pointers
80GB disk …
Still has spare pointers
Min physical cluster size:
1 sector or 512 bytes
Min cluster used:
2 sectors or 1KBFAT16 vs. FAT32
chkdsk c: /f … Not enough memory for everyone.
check c: for errors and fix them
from DOS prompt
older: only Win 9x
better with windows up
only win 9x
defragment a drive
… well, try the help prompt for it first
Win XP facilities
chkdsk still works
need to disable some things
else chkdsk restartsDisk error checks
chkdisk & defrag: … Not enough memory for everyone.
need to disable:
reset from clean boot:
general tab click Normal start-up
load system services
Hide all Microsoft Services, Disable All
OK restartClean Boot for Windows XPMs article 310353
win 9x … Not enough memory for everyone.
partition info, all drives
screens to display or modify partitions
repairs a damaged MBR
prep a drive for 1st use
similar to fdisk
similar to fdisk /mbrPartitioning disks
formatting a disk with a file system: see format /?
Disk Defragmenter … Not enough memory for everyone.
Collect file fragments
rewrite in contiguous space
many slow trips … Not enough memory for everyone.
few slow trips
many fast trips