Part V Bits and Bytes. 17/1 17/2 Part V Bits and Bytes Blank page. Chapter 17 Hardware and Peripherals 17.1 ... Memory The microprocessor was a significant key to lowering the cost of the personal computer. However the other key and an equally important one was low-cost semiconductor memory. Semiconductor memory started replacing magnetic core memory around 1967. Their are two types of semiconductor Random Access Memory (RAM). Dynamic RAM (DRAM) requires periodic refresh of the memory contents and Static RAM (SRAM) retains the contents without refresh. Both types of RAM loose their contents when the power is turned off. Read only memory (ROM) retains its contents once it is programmed, even when the power is turned off. The first commercial 1K metal oxide semiconductor DRAM was the Intel 1103 released in October 1970. This chip had a pivotal role in undercutting the price and replacement of core memory. Intel continued to improve DRAM capacities with the release of the 4K 2107 chip in 1972 and the 16K 2117 chip in 1977. However, competitive challenges from Japanese companies, would have a significant impact on Intel and other North American producers of memory chips. Japan decided to make a strategic investment in the semiconductor memory industry around in the late 1970’s. The effect of this was the first open market release of a 64K DRAM chip by Fujitsu Limited in 1979, and introduction of the first 1-megabit DRAM chip by the Toshiba Corporation in 1985. A number of other factors contributed to the dominance of Japanese manufacturers in the 1980’s. Some of these were: a cooperative relationship between various companies in the Japanese industry, illegal use of U.S. technology, superior quality that contributed to lower costs and a significant investment in new facilities to produce memory chips. This resulted in a price war by the Japanese producers to increase their market share through the early 1980’s. By 1985 the market situation 17/3 17/4 Part V Bits and Bytes for North American producers had so deteriorated, that the U.S. Government accused Japan of unfair trading practices and filed an antidumping complaint against the Japanese manufacturers. A semiconductor agreement was signed by the governments of Japan and the United States in 1986. However, by this time it had adversely affected many U.S. companies such as the Intel Corporation that had already decided to withdraw from the DRAM market. The company also withdrew from the EPROM chip market in 1989. Erasable Programmable Read-Only Memory (EPROM) was invented by Dov Frohman at Intel. The memory contents can be programmed then erased by exposing the chip to ultraviolet light. Intel released the 2K-bit 1702 EPROM chip in September 1971. This alterable storage medium provided a low cost way to store microcomputer programs and became a successful and extremely profitable product for Intel until the mid 1980’s. Flash memory was developed by Toshiba. It provided the non-volatility of EPROM but the memory could be erased electrically. Electrically Erasable Programmable Read-Only Memory (EEPROM) was developed by National Cash Register (NCR) and Westinghouse companies. 17.2 ... Storage Devices Tape Drives Paper tape was one of the earliest forms of storage for personal computing. However it normally required a teletype machine for input/output that was too expensive for the average user. Another early storage medium for personal computers was the magnetic audio cassette tape and the subsequent digital data cassette. Information Terminals Corporation (ITC) was the first producer of high quality data cassettes. The company was founded by J. Reid Anderson in April 1969. Anderson had previously developed acoustic-coupler modems and a prototype for a “smart” computer display terminal. During the development of the computer display terminal, Anderson Hardware and Peripherals 17/5 determined that audio tape cassettes were not a sufficiently reliable storage medium for recording digital data. The audio cassettes did not have a uniform magnetic coating or a precise cassette body that resulted in “dropouts” or lost data. This resulted in the development of a high quality, precision data cassette that ITC started producing in 1970. The company became the dominant supplier of digital data cassettes in the 1970’s. ITC introduced a mini cassette for portable data processors and a quarter-inch data cartridge in 1975. A new superior coating media for tapes and disks named Verbatim, was announced in February 1977. The company changed its name to Verbatim Corporation in late 1978, and went public in February 1979. The 3M company introduced quarter-inch tape drive media in 1971. The capacity of these early drives was only 30 megabytes. Jerry Ogdin developed the concept of using two tones on magnetic tape to represent digital data. This was implemented in a Popular Electronics construction article with the name of HITS (Hobbyists’ Interchange Tape System) in September 1975. It was inexpensive and was adapted by many manufacturers. Initially each company had their own formatting standards. However in November 1975 BYTE magazine organized a meeting in Kansas City, Missouri of interested companies. The companies agreed to a format that became known as the “Kansas City Standard.” This standard facilitated the exchange and use of magnetic tapes on different systems. Disk Drives The Beginning at IBM Hard disk drive technology was developed by IBM in the 1950’s as described in Section 1.3. The first Winchester hard disk drive was announced by IBM in March 1973 as the Model 3340 Disk Storage Unit. It was developed as a low-cost drive for small to intermediate computer systems. The term Winchester was used by the engineers due to the storage capacity characteristics and similarities to the name of a popular rifle as 17/6 Part V Bits and Bytes described in Section 20.4. A principal in the development was Kenneth E. Haughton who had assumed responsibility for the project in 1969. The drive assembly used a removable sealed cartridge with 14-inch diameter disks and was available in 35 and 70 megabyte storage capacities. Floppy disk drives were developed at IBM laboratories by David L. Noble during the period of 1967 to 1971. They were initially developed by IBM as a means of storing and shipping microcode for Initial Control Program Load (ICPL) software programs on mainframe computers. The jacket enclosing the diskette was developed to protect the disk during handling and shipping. The initial eight inch diameter read only units had a product designation of 23FD, a code name of Minnow and shipped in 1971. The diskette on the read only units rotated at 90 revolutions per minute and data was recorded on one side only. The diskette capacity was 81,664 bytes on 32 tracks which were hard sectored with eight holes around the outer edge of the disk. The eight inch diameter read-write units had a product designation of 33FD, a code name of Igar and shipped in 1973. The diskette on the read-write drive units rotated at 360 revolutions per minute, had a capacity of 242,944 bytes on 77 tracks which was recorded on one side only and used magnetic soft sectoring (no sector holes). The 33FD diskette drive was a success and was used in data entry products which started to replace IBM card systems. In 1976 the 43FD unit was shipped with data being recorded on both sides and capacity increased to 568,320 bytes on 154 tracks. In 1977 the 53FD double-density unit was shipped with capacity increased to 1,212,416 bytes. IBM’s research and development activities created the Winchester hard disk drives and the floppy disk drives. However other companies entered the market to compete with IBM products and to provide disk drives for other computer systems. Some of these manufacturers were Control Data Corporation (CDC), Conner Peripherals, Hardware and Peripherals 17/7 Maxtor, Micropolis Corporation, MiniScribe, Quantum Corporation, Seagate Technology, Shugart Associates and Western Digital Corporation. In the mid 1970’s, hard disk drives were not suitable for use with microcomputers due to their large size and high cost. However by 1976, inexpensive floppy disk drives became available for personal computers. Floppy Disk Drives Alan F. Shugart joined IBM as a customer engineer in 1951. After a number of positions related to memory and storage technology he became manager for direct access storage products. Shugart left IBM in 1969 to become manager of storage products at Memorex. In 1973 Shugart left Memorex and with Finis F. Connor and Donald J. Massaro founded Shugart Associates. The company announced the SA-900 8-inch floppy diskette drive that retailed for $500 in the summer of 1973. After two years Shugart had a dispute regarding capitalization of the company and left. Shugart Associates announced the SA- 400 5.25-inch minifloppy disk drive for $390 in December 1976. The drive used a single-sided single-density floppy disk with a capacity of 110 kilobytes. Shugart Associates was acquired by Xerox Corporation in 1977. However it was not profitable and resulted in Xerox terminating Shugart operations in 1985. The first advertisement for a microcomputer floppy disk drive in the Byte magazine appeared in the August 1976 issue. The eight inch drive is described as "iCOM's Frugal Floppy. At $995, your microprocessors best friend." It was produced by iCOM Microperipherals that was a division of the Pertec Computer Corporation. Then in the February 1977 issue of Byte, iCOM advertised a 5.25-inch Microfloppy disk drive system for $1,095. North Star Computers, was another early manufacturer of floppy disk drives for MITS Altair and compatible microcomputers. The company advertised the Micro-Disk System (MDS) in the January 1977 issue of Byte magazine.