Chapter 14

CD - Media

CD-ROM Drives Developed in the late 1970’s by Sony and

Philips as a replacement for vinyl records Used for music but later discovered that PC

data could be stored on the CD

How CD-ROM’s Work CD-ROMs store data using microscopic

pits burned into a glass master CD-ROM powerful laser

With master, plastic copies are recreated using a very high-tolerance infection molding process

Coated with reflective metallic coating, and then coated with lacquer for protection

How CD-ROMs Work Cont. CD-ROM drives use a laser and mirrors to

read the data off of the CD-ROM The pits don’t allow reflection, creating

binary 1’s, and the non-pitted spots make binary 0’s

CD-ROM Formats CD-Audio divides the CD’s data into variable

length tracks; terrible for data storage To store data on a CD-ROM required error

checking(ISO-9660 or High Sierra) CD interactive-(CD-I)store sound and video;

simultaneous playback CD-ROM/XA-advanced CD-I Kodak’s Photo-CD- compressed to store many

pictures on

MPC Multimedia Personal Computer- defines a

set of minimum standards for multimedia system

So far outclassed

CD-ROM Speeds First CD-ROM drives processed data at

roughly 150KBps(CD-Audio speed) As speed increased, measured in multiples

of the original 150KBps drives 1x, 32x, 72x...

CD-R CD-recordable 2 types: 74min,650Mb or 80min,700 Mb Require CD-R drive to “burn” “Burn” laser heats the organic dye, causing

a change in the reflectivity of the surface (simulates pits)

Single or multi -session drives 2 speeds: record speed x read speed

CD-RW CD-ReWrite Use a laser to heat the non crystalline

substance that when cooled, becomes crystalline

The crystalline areas are reflective, whereas the amorphous areas are not.

write speed x re-write speed x read speed

Connections At first, there was no standard connections

for CD-ROM The ATAPI used the 40 pin EIDE ribbon

and master/slave jumpers(like drive) Require no CMOS as part of the

installation control

Connections (continued) SCSI chain enables many CD-ROM drives

to be installed on one machine (networks) Faster than EIDE but needs a unique SCSI

ID and needs to be terminated at end of chain

Device Drivers/Software The operating system wants to give a CD

media drive a drive letter that can be accessed by the OS

Varies according to OS

DOS Device Drivers Needs a hardware-specific device driver

installed via CONFIG.SYS to create an interface for the CD-ROM

Needs a hardware non-specific program called MSCDEX in order to give drive a letter

SCSI DOS Device Drivers Needs 2 device drivers: the DOS device

driver for the host adapter and the DOS ASPI driver for CD_ROMs, ASPICD.SYS

ATAPI DOS Device Drivers Not a high level of standardization of

drivers in SCSI CD-ROMs However, it only needs one device driver OAKCDROM.SYS found on internet as a

download

MSCDEX Microsoft CD-ROM Extensions It takes the device set up in the CD-ROM’s

device driver line and assigns it a drive letter

Windows 9x & 2000 Device Drivers Replace MSCDEX with the protected-

mode CD File System Drivers ISF drivers enable tighter integration of

different types of storage devices

Device Manager and Settings Allows you to make changes and find

information of your drive in Windows Where you enable AutoPlay which

automatically detects to presence of a CD when inserts

Troubleshooting Check connectors Check in boot up if device is found and if

not use start up disk Check other disks(CD- ROM, R, RW) Might have to clean drive Clean CD with damp cloth CD scratches worse on top than bottom