DC100
{{short description|Magnetic tape storage format}}
{{multiple image|image1=HP85 Computer Teardown (27834341303).jpg|image2=HP85 Computer Teardown (28167529860).jpg|direction=vertical|footer=DC100 tape cartridge and transport from an HP 85 desktop computer}}
DC100 (also known as DC100A) is a tape cartridge format that was co-developed by Hewlett-Packard and 3M. Introduced in mid-1976,{{cite journal | last=Sinden | first=Ken | date=July 1976 | url=https://archive.org/details/sim_data-processing_july-august-1976_18_5/page/39/mode/1up?q=3m+%22DC-100a%22 | title=Storage for small systems | work=Data Processing | publisher=IPC Electrical-Electronic Press | volume=18 | issue=5 | pages=39–40 | via=the Internet Archive}} it was developed as a data storage mechanism for the HP 9820 programmable calculator.{{cite web | last=Leibson | first=Steve | date=August 25, 2006 | url=http://www.hp9825.com/html/dc100_tape.html | title=The DC100 Tape and Drive: Accidental Start of a New Industry | work=HP9825.com | archiveurl=https://web.archive.org/web/20230207202432/http://www.hp9825.com/html/dc100_tape.html | archivedate=February 7, 2023}} The DC100 tape cartridge was a scaled-down version of the DC300 cartridge pioneered by 3M, and represents an early version of what is now referred to as the QIC Mini Cartridge.{{cite web | last=Leibson | first=Steve | date=July 19, 2007 | url=https://www.edn.com/the-qic-and-the-dead/ | title=The QIC and the Dead | work=EDN | publisher=AspenCore | archiveurl=https://archive.today/20230218202704/https://www.edn.com/the-qic-and-the-dead/ | archivedate=February 18, 2023}} 3M was the exclusive source of DC100 tapes,{{cite journal | last=McLeod | first=Jonah | date=September 1982 | url=https://archive.org/details/sim_systems-software_1982-09_1_1/page/n29/ | title=Small storage peripherals grow even smaller in cost and size | work=Systems & Software | publisher=Hayden Publishing | volume=1 | issue=1 | pages=37–43 | via=the Internet Archive}} while drives were manufactured by 3M and several third parties.
History
The DC100 tape cartridge format was used in the HP desktop calculator and computer systems of the late 1970s and early 1980s, including the 9815, 9825, 9845, and HP Series 80.{{cite journal | last=King | first=Russell | date=September 1981 | url=https://archive.org/details/Kilobaud198109/page/n119/ | title=What's So Super About the HP-85? | work=Kilobaud Microcomputing | publisher=Wayne Green, Inc. | volume=V | issue=9 | pages=120–125 | via=the Internet Archive}} HP also used it in their 2640 series of computer terminals.{{cite journal | last=Nordman | first=Robert G. | author2=Richard L. Smith | author3=Louis A. Witkin | date=May 1976 | url=https://archive.org/details/Hewlett-Packard_Journal_Vol._27_No._9_1976-05_Hewlett-Packard/page/n1/ | title=New CRT Terminal Has Magnetic Tape Storage for Expanded Capability | work=Hewlett-Packard Journal | publisher=Hewlett-Packard | volume=27 | issue=9 | pages=2–15 | via=the Internet Archive}} Tape transports were manufactured by 3M, as well as North Atlantic Qantex,{{cite journal | last=Staff writer | date=December 5, 1977 | url=https://archive.org/details/sim_computerworld_1977-12-05_11_49/page/64/ | title=Transport Suits 3M Cartridge | work=Computerworld | publisher=CW Communications | volume=11 | issue=49 | page=64 | via=the Internet Archive}}{{cite journal | last=Staff writer | date=May 29, 1978 | url=https://archive.org/details/sim_computerworld_1978-05-29_12_22/page/n117/ | title=Qantex Division | work=Computerworld | publisher=CW Communications | volume=12 | issue=22 | page=P/46 | via=the Internet Archive}} Instrumentation Technology Corporation,{{cite journal | last=Staff writer | date=September 1976 | url=https://archive.org/details/bitsavers_computerDe_156266120/page/160/ | title=Data Cartridge Transport | work=Computer Design | volume=15 | issue=9 | page=160 | via=the Internet Archive}} and Beehive International.{{cite journal | last=Staff writer | date=August 6, 1979 | url=https://archive.org/details/sim_computerworld_1979-08-06_13_32/page/40/ | title=Beekeeper Stores Data Off-Line for Beehive Units | work=Computerworld | publisher=CW Communications | volume=13 | issue=32 | page=40 | via=the Internet Archive}}
Outside of HP, the format suffered from poor adoption rates four years after its introduction, according to Wayne Green.{{cite journal | last=Green | first=Wayne | authorlink=Wayne Green | date=November 1980 | url=https://archive.org/details/Kilobaud198011/page/n7/ | title=Publisher's Remarks | work=Kilobaud Microcomputing | publisher=Wayne Green, Inc. | pages=6–8 | via=the Internet Archive}} Bucking this trend, Computer Automation's LSI-2 minicomputers saw compatibility with the DC100 format with the release of the TDCA-100 tape transport system by Telegenix in 1981.{{cite journal | last=Staff writer | date=February 23, 1981 | url=https://archive.org/details/sim_computerworld_1981-02-23_15_8/page/n129/ | title=Tape System Fits CA's LSI-2 | work=Computerworld | publisher=CW Communications | volume=15 | issue=8 | page=66 | via=the Internet Archive}} In 1984, Irwin Magnetic Systems introduced the Irwin 210 tape backup unit for various platforms that used DC100 tape.{{cite journal | last=Staff writer | date=March 5, 1984 | url=https://archive.org/details/sim_micro-marketworld_1984-03-05_7_5/page/n68/ | title=Micro-sized backup targets tape drives | work=Micro Marketworld | publisher=IDG Publications | volume=7 | issue=5 | page=67 | via=the Internet Archive}}
Digital Equipment Corporation's DC150 cartridge, a variation of DC100 with slightly higher capacity, was used in DEC's DECtape II drives.{{cite journal | last=Staff writer | date=September 14, 1978 | url=https://worldradiohistory.com/Archive-Electronics/70s/78/Electronics-1978-09-14.pdf | title=Tape unit offers random access | work=Electronics | publisher=McGraw-Hill | volume=51 | issue=19 | pages=222–224 | via=World Radio History}} HP later developed the DC200 tape cartridge format on their own; it was based on the design of the DC100 but used thinner tape to increase the amount of data over its predecessor.
Specifications
| class="wikitable"
|+ Comparison between DC100 and DC300 ! Property ! DC100(A) !! DC300 |
| Release date |
|---|
| Unformatted capacity |
| Formatted capacity{{efn|1,000 bytes per block}} |
| Transfer speed |
| Tape length |
| Tape width |
| Transport size {{small|(3M-manufactured)}} |
| Tracks |
| Recording density ({{abbr|ftpi|flux transitions per inch}}) |
| Coercivity (Oe) |
; Notes
{{notelist}}
- Base plate flatness.
- Guide posts (essentially the 5 "axles" in the cartridge) into the base plate with sufficient perpendicularity.
- Guide-post surface finish. Too rough, abraded the back of the tape. Too smooth, tape adheres to the guide through stiction, which causes speed flutter on the tape. The right surface treatment was found to be lapidary tumbler, a recipe of abrasive and burnishing compound.
- Guide-post perpendicularity had to be right to avoid differential tension on the tape. In the severe case contact between tape and head was lost. The two most critical guide posts in the manufacture fixture, the hub bearing or axle posts, had to be perpendicular to within approximately 1/3° degrees.
- Lubrication.
- Cartridge’s internal plastic drive belt (critical).
; HP improvements on the 3M design
- Tape tension is controlled primarily by friction in two rollers that the belt loops around. 3M controlled belt-roller friction (and hence the tape tension) with a very precise amount of STP lubricant on the bearing surfaces. A better design was to use large axles and Teflon-filled plastic for the bearing rollers, which eliminated the need for lubrication.
- Minimum tape tension at the head was increased, the drive force to spin the drive puck was less however.
- Optical sensing of cartridge in and write protect.
References
{{reflist|colwidth=30em}}
External links
- {{cite patent |country=United States |number=3692255 |inventor=Robert A. Von Behren |status=patent |title= Belt driven tape cartridge |fdate=June 17, 1971 |gdate=September 19, 1975 |assign1=Minnesota Mining and Manufacturing Company |url=https://www.hp9845.net/9845/downloads/patents/US3692255.pdf}}
- [http://www.hp9825.com/assets/images/DC100_Tape_and_Drive02.jpg Picture of DC100 drive] at HP9825.com
{{Magnetic tape data formats}}
Category:Computer-related introductions in 1976