The Macintosh
Hard Disk 20 was the first hard drive developed by
Apple ComputerApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
specifically for use with the
Macintosh 512KThe Macintosh 512K Personal Computer, the second of a long line of Apple Macintosh computers, was the first update to the original Macintosh 128K. It was virtually identical to the previous Mac, differing primarily in the amount of built-in memory , which quadrupled the original's. This large...
. Introduced on September 17, 1985, it was part of Apple's long awaited solution toward completing the
Macintosh OfficeConsisting of three key parts: a network file server, local area network and a network Laser printer, The Macintosh Office was Apple's third failed attempt to enter into the business environment as a serious competitor to IBM...
(a suite of integrated business hardware & software) announced in January 1985. Unfortunately it would be over a year more before Apple would release the file server software
AppleShareAppleShare was a product from Apple Computer which implemented various network services. Its main purpose was acting as a file server, using the AFP protocol...
that would link all of the hardware together.
The Macintosh
Hard Disk 20 was the first hard drive developed by
Apple ComputerApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
specifically for use with the
Macintosh 512KThe Macintosh 512K Personal Computer, the second of a long line of Apple Macintosh computers, was the first update to the original Macintosh 128K. It was virtually identical to the previous Mac, differing primarily in the amount of built-in memory , which quadrupled the original's. This large...
. Introduced on September 17, 1985, it was part of Apple's long awaited solution toward completing the
Macintosh OfficeConsisting of three key parts: a network file server, local area network and a network Laser printer, The Macintosh Office was Apple's third failed attempt to enter into the business environment as a serious competitor to IBM...
(a suite of integrated business hardware & software) announced in January 1985. Unfortunately it would be over a year more before Apple would release the file server software
AppleShareAppleShare was a product from Apple Computer which implemented various network services. Its main purpose was acting as a file server, using the AFP protocol...
that would link all of the hardware together. By that time the
SCSISmall Computer System Interface, or SCSI , 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...
interface introduced on the
Macintosh PlusThe 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 2599 USD . As an evolutionary improvement over the 512K, it introduced RAM...
in January 1986, would accommodate far faster and more efficient hard drives, rendering the Hard Disk 20 virtually obsolete.
Features
The Hard Disk 20 (or
HD20, as it was known colloquially) contained a 20MB 3.5"
RodimeRodime was an electronics company specialising in hard disks, based in Glenrothes, Scotland. It was founded in 1979 by several Scottish and American former employees of Burroughs Corporation and listed on the London Stock Exchange in 1986, becoming Rodime PLC....
hard diskA hard disk drive is a non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to the motorized mechanical aspect that is distinct from its medium, such as a tape drive and its tape, or a floppy disk...
which provided over 50 times the data storage of the stock 400K disk drive. At a time when the average file size was around 10-20K and due to the vast number of those files the HD 20 could contain, Apple's original
Macintosh File SystemMacintosh File System is a volume format created by Apple Computer for storing files on 400K floppy disks. MFS was introduced with the Macintosh 128K in January 1984....
, which did not allow for directories, would have made organizing those files unwieldy. Therefore Apple introduced it with a new System and Finder update which included the brand new
Hierarchical File SystemHierarchical File System , is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
allowing the user to better organize files on such a large volume. As a result only the
Macintosh 512KThe Macintosh 512K Personal Computer, the second of a long line of Apple Macintosh computers, was the first update to the original Macintosh 128K. It was virtually identical to the previous Mac, differing primarily in the amount of built-in memory , which quadrupled the original's. This large...
could access it, the original
Macintosh 128KThe Macintosh is the original Apple Macintosh personal computer. Its beige case contains a 9-inch monitor and comes with a keyboard and mouse. An indentation in the top of the case allows the computer to be lifted and carried. It had a selling price of US$2,495...
did not have enough
RAM-Ram, ram, or RAM as a non-acronymic word:As a non-acronymic word Ram, ram, or RAM may refer to:-Animals:*Bighorn Sheep, A North American mountain sheep species*Sheep, an uncastrated male of which is called a ram...
to load the new file system. In fact, even for the Macintosh 512K to use the drive, it required an additional file in the System Folder on a special startup disk which added additional code into memory during startup. An ingenious startup routine also allowed the Mac to check for the presence of a System file on the Hard Disk, switch over to it and eject the startup disk. Unfortunately, the HD 20 could not be used as a startup disk directly without first loading the code from the floppy disk drive. With the release of the
Macintosh PlusThe 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 2599 USD . As an evolutionary improvement over the 512K, it introduced RAM...
and the
Macintosh 512KeThe Macintosh 512K enhanced was introduced as a cheaper alternative to the top-of-the-line Macintosh Plus. It was the same as the Macintosh 512K but with the 800K disk drive and 128K of ROM like the Plus. Like its predecessors, there was little room for expansion...
, both containing the upgraded 128K
ROMRead-only memory is a class of storage media used in computers and other electronic devices. Because data stored in ROM cannot be modified , it is mainly used to distribute firmware .In its strictest sense, ROM...
which contained the additional code, the HD 20 could finally be used alone as a startup disk.
While other hard drives were available on the market, Apple's HD 20 was generally preferred mainly because Apple broke their own development rules when they offered it. Originally the Macintosh was designed with two
serial portIn computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
s which were to provide all the expansion needs required of the user. It also included a dedicated floppy disk port for one external floppy disk. Most of the hard drives which were available on the market used the slower
serial portIn computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
to transfer data per Apple's specifications. Apple instead engineered the HD 20 to use the faster floppy disk port, enabling the user to daisy-chain an external floppy disk drive as well as an additional HD 20. With few exceptions, this along with complete compatibility with the new
Hierarchical File SystemHierarchical File System , is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
, gave Apple an instant edge over the competition. In addition, the HD 20 had a convenient "zero-footprint" design which fit precisely underneath the Macintosh, merely elevating it 3 inches, but otherwise taking up no more desk-space.
History
In 1985, the HD 20 was an important step to solidifying the Macintosh as a true business computer and it was eagerly anticipated following its April announcement. Until Apple's introduction a year later of the
Hard Disk 20SCThe Apple Hard Disk 20SC 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.-History:Released...
, the first SCSI drive they manufactured, the HD 20 was the only Apple manufactured hard drive available for any Macintosh (not including the
Macintosh XLMacintosh XL was a modified version of the Apple Lisa personal computer made by Apple Computer, Inc. In the Macintosh XL configuration, the computer shipped with MacWorks XL, a Lisa program that allowed 64K Macintosh ROM emulation...
). The HD20 was not compatible with any other Apple computer or other platforms.
However, the HD 20's unique design and position in the marketplace, was quickly outmoded by the advancement of the significantly faster
SCSISmall Computer System Interface, or SCSI , 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...
standard which also debuted with the Macintosh Plus in January 1986. Some third party companies offered a
SCSISmall Computer System Interface, or SCSI , 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...
conversion kit which replaced the controller board thus preserving the user's investment in the expensive but proprietary Rodime drive. Apple officially dropped support for the HD 20 with
System 6System 6 is a graphical user interface-based operating system for Macintosh computers. It was released in 1988 by Apple Computer and was part of the Mac OS line of operating systems. System 6 was shipped with various Macintosh computers until it was succeeded by System 7 in 1991. The boxed...
as well as omitting the necessary ROM code beginning with the
Macintosh SE/30The Macintosh SE/30 is a personal computer that was designed, manufactured and sold by Apple Computer, Inc. from 1989 until 1991. It was the fastest and most expandable of the original black-and-white compact Macintosh series....
. Sales of the HD 20 continued to support the Macintosh 512Ke which had no other hard drive options until it was discontinued in late 1987. Apple quickly dropped support for the HD 20 in all of its newer Macs, only to find many business users upgrading their older systems needed a way to transfer data from the unsupported drives to the newer Macs. Only Macs with legacy technology and floppy disk ports, which were eliminated entirely from Macintosh computers in 1991, were able to continue to use the older slower technology.
Manufactured in significant numbers for almost two years, The HD 20 remains as one of the few surviving hard drives a stock Macintosh 512K or 512Ke can use.
External links