Hard Disk 20SC
Encyclopedia
The Apple Hard Disk 20SC (not to be confused with the Apple Macintosh Hard Disk 20
, the first hard drive manufactured by Apple exclusively for the original Macintosh floppy disk drive port interface) was Apple's first SCSI
based hard drive for the Apple II
family as well as the Macintosh
and other third party computers using an industry standard SCSI interface.
(which required an optional SCSI interface card
to use it), it debuted over 9 months after the introduction of the Macintosh Plus
, the first to include Apple's SCSI interface. It was a welcome addition, delivering considerably faster data transfer rates (up to 1.25 megabytes per second) than its predecessors, the Hard Disk 20 (62.5 Kilobytes per second) and ProFile
.
and SE
. It had two standard Centronics
50-pin connectors, one for the System and one for daisy-chaining additional SCSI devices and a SCSI ID selection switch. An external terminator was required if it was the only SCSI device connected. The case itself could accommodate a 3.5" or 5.25" full-height hard drive mechanism. Indeed the case design would be reused unchanged (in Platinum only) for 3 more models introduced the following year: 40SC, 80SC & 160SC (offering respective Megabyte
s of storage). While the transfer rates were significantly higher due to the faster SCSI bus technology, the actual transfer rate varied from computer to computer thanks to different SCSI implementation based on developing industry standards.
. Notably, it was the only Snow White product to use the Macintosh beige color and one of the few Apple products to be introduced in two different colors at the same time. Since the Apple IIGS was the first Apple product to debut in the new gray color they called Platinum, the 20SC had to both match it and the beige color of the Macintosh Plus, which it is designed to sit perfectly beneath. In 1987, all Apple products would change to Platinum, which would remain in use for the next 10 years.
Hard Disk 20
The Macintosh Hard Disk 20 was the first hard drive developed by Apple Computer specifically for use with the Macintosh 512K. Introduced on September 17, 1985, it was part of Apple's long awaited solution toward completing the Macintosh Office announced in January 1985...
, the first hard drive manufactured by Apple exclusively for the original Macintosh floppy disk drive port interface) was Apple's first SCSI
SCSI
Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...
based hard drive for the Apple II
Apple II
The Apple II is an 8-bit home computer, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977...
family as well as the Macintosh
Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
and other third party computers using an industry standard SCSI interface.
History
Released in September 1986 along with the Apple IIGSApple IIGS
The Apple , the fifth and most powerful model in the Apple II series of personal computers produced by Apple Computer. The "GS" in the name stands for Graphics and Sound, referring to its enhanced graphics and sound capabilities, both of which greatly surpassed previous models of the line...
(which required an optional SCSI interface card
Apple II peripheral cards
The Apple II line of computers supported a number of Apple II peripheral cards, expansion cards which plugged into slots on the motherboard, and added to and extended the functionality of the base system....
to use it), it debuted over 9 months after the introduction of the Macintosh Plus
Macintosh Plus
The Macintosh Plus computer was the third model in the Macintosh line, introduced on January 16, 1986, two years after the original Macintosh and a little more than a year after the Macintosh 512K, with a price tag of US$2599...
, the first to include Apple's SCSI interface. It was a welcome addition, delivering considerably faster data transfer rates (up to 1.25 megabytes per second) than its predecessors, the Hard Disk 20 (62.5 Kilobytes per second) and ProFile
Profile
- Computing and technology :* Profile , a concept in Unified Modeling Language* Apple ProFile, a hard drive* User profile refers to the computer representation of user information...
.
Hardware
The 20SC originally contained a half height 5.25" Seagate ST-225N 20MB SCSI hard drive, but was later manufactured with a full-height 3.5" MiniScribe 8425SA 20MB SCSI hard drive. The latter drive was the same size as the drive inside the Macintosh Hard Disk 20, but 10 to 15 MB over what had previously been offered by Apple for the II family. The same drive mechanism would also be offered 6 months later as a built-in drive option on the Macintosh IIMacintosh II
The Apple Macintosh II was the first personal computer model of the Macintosh II series in the Apple Macintosh line and the first Macintosh to support a color display.- History :...
and SE
Macintosh SE
The Macintosh SE was a personal computer manufactured by Apple between March 1987 and October 1990. This computer marked a significant improvement on the Macintosh Plus design and was introduced by Apple at the same time as the Macintosh II....
. It had two standard Centronics
Centronics
Centronics Data Computer Corporation was a pioneering American manufacturer of computer printers, now remembered primarily for the parallel interface that bears its name.-The beginning:Centronics began as a division of Wang Laboratories...
50-pin connectors, one for the System and one for daisy-chaining additional SCSI devices and a SCSI ID selection switch. An external terminator was required if it was the only SCSI device connected. The case itself could accommodate a 3.5" or 5.25" full-height hard drive mechanism. Indeed the case design would be reused unchanged (in Platinum only) for 3 more models introduced the following year: 40SC, 80SC & 160SC (offering respective Megabyte
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...
s of storage). While the transfer rates were significantly higher due to the faster SCSI bus technology, the actual transfer rate varied from computer to computer thanks to different SCSI implementation based on developing industry standards.
Design
In addition to being the first cross-platform drive offered by Apple it was the first hard drive to use the Snow White design languageSnow White design language
The Snow White design language was an industrial design language developed by Hartmut Esslinger's Frog Design. Used by Apple Computer from 1984 to 1990, the scheme has vertical and horizontal stripes for decoration, ventilation, and the illusion that the computer enclosure is smaller than it...
. Notably, it was the only Snow White product to use the Macintosh beige color and one of the few Apple products to be introduced in two different colors at the same time. Since the Apple IIGS was the first Apple product to debut in the new gray color they called Platinum, the 20SC had to both match it and the beige color of the Macintosh Plus, which it is designed to sit perfectly beneath. In 1987, all Apple products would change to Platinum, which would remain in use for the next 10 years.