Chuck Forsberg: Difference between revisions
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WardXmodem (talk | contribs) Add details of how Ymodem came about, from personal experience (phone call with Chuck) |
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The widely adopted [[ZMODEM]] used a [[sliding window protocol]]. Rather than wait for positive acknowledgment after each block is sent, it sent blocks in rapid succession and resent unacknowledged blocks later. By avoiding delays due to [[latency (engineering)|latency]], the bandwidth usable for transmission more closely approached the [[bandwidth (computing)|bandwidth]] of the underlying link. ZMODEM could also resume interrupted transfers without retransmitting the already-received blocks. In addition to developing the protocol, Forsberg developed [[software]] for sending and receiving files using ZMODEM. |
The widely adopted [[ZMODEM]] used a [[sliding window protocol]]. Rather than wait for positive acknowledgment after each block is sent, it sent blocks in rapid succession and resent unacknowledged blocks later. By avoiding delays due to [[latency (engineering)|latency]], the bandwidth usable for transmission more closely approached the [[bandwidth (computing)|bandwidth]] of the underlying link. ZMODEM could also resume interrupted transfers without retransmitting the already-received blocks. In addition to developing the protocol, Forsberg developed [[software]] for sending and receiving files using ZMODEM. |
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Chuck then wrote a version Zmodem G, which was for use over "guaranteed error free" communications lines, such as Ethernet or short serial-to-serial computer connections. This protocol waived the usual retransmission overhead, to send files as fast as possible. |
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Previously, he designed the [[YMODEM]] protocol and created its first [[implementation]], a program called ''YAM''. |
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Originally, he wrote a program for Unix called rbsb (receive batch / send batch) which used block 0 to transmit a file's name, and optionally date and time, since [[Ward Christensen]] designed [[Xmodem]] to start at block 1, leaving block 0 ''available''. At one point Ward, in a phone call to Chuck, suggested calling his protocol [[Ymodem]] because it was "one better" than [[Xmodem]]. Chuck created the program ''YAM'' which in traditional Unix nomenclature, stood for ''Yet Another Modem'' after "Modem.asm" the original version of [[Xmodem]] released by Ward in the CP/M User's group in 1977. |
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Forsberg most recently resided in [[Portland, Oregon]] prior to his death. He ran data transmission software company Omen Technology which he founded in 1984.<ref name="autogenerated1">{{cite web |url=http://www.omen.com/about.html |title=About Omen Technology |accessdate=2012-02-16 |deadurl=bot: unknown |archiveurl=https://web.archive.org/web/20150915193210/http://www.omen.com/about.html |archivedate=September 15, 2015 |df= }}</ref> He was an amateur radio operator (call sign WA7KGX)<ref>{{cite web | url = http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=862831 | title = Amateur License – WA7KGX – FORSBERG, CHARLES A | accessdate = 2012-02-16}}</ref> and a licensed aircraft pilot.<ref name="autogenerated1"/> |
Forsberg most recently resided in [[Portland, Oregon]] prior to his death. He ran data transmission software company Omen Technology which he founded in 1984.<ref name="autogenerated1">{{cite web |url=http://www.omen.com/about.html |title=About Omen Technology |accessdate=2012-02-16 |deadurl=bot: unknown |archiveurl=https://web.archive.org/web/20150915193210/http://www.omen.com/about.html |archivedate=September 15, 2015 |df= }}</ref> He was an amateur radio operator (call sign WA7KGX)<ref>{{cite web | url = http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=862831 | title = Amateur License – WA7KGX – FORSBERG, CHARLES A | accessdate = 2012-02-16}}</ref> and a licensed aircraft pilot.<ref name="autogenerated1"/> |
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Revision as of 20:09, 21 June 2018
Charles Alton Forsberg | |
|---|---|
| Born | May 6, 1944 Wilmette, Illinois, USA |
| Died | September 24, 2015 (aged 71) Portland, Oregon, USA |
| Nationality | United States |
| Other names | Chuck Forsberg |
| Education | M.S., Electrical engineering (1968)[1] |
| Alma mater | University of Wisconsin |
| Years active | 1968–? |
| Notable work | YMODEM, ZMODEM |
| Engineering career | |
| Discipline | Computer engineering |
| Employer(s) | Tektronix |
| Projects | Tektronix 4010 |
| Awards | Dvorak Award for Excellence in Telecommunications |
Charles Alton "Chuck" Forsberg (May 6, 1944 – September 24, 2015)[1] developed two data transmission protocols popular for uploading and downloading files from dial-up bulletin board systems in the 1990s. He received a Dvorak Award for Excellence in Telecommunications in 1992 for developing ZMODEM.[2] He was also the project engineer on the Tektronix 4010-series graphics terminals.
The widely adopted ZMODEM used a sliding window protocol. Rather than wait for positive acknowledgment after each block is sent, it sent blocks in rapid succession and resent unacknowledged blocks later. By avoiding delays due to latency, the bandwidth usable for transmission more closely approached the bandwidth of the underlying link. ZMODEM could also resume interrupted transfers without retransmitting the already-received blocks. In addition to developing the protocol, Forsberg developed software for sending and receiving files using ZMODEM.
Chuck then wrote a version Zmodem G, which was for use over "guaranteed error free" communications lines, such as Ethernet or short serial-to-serial computer connections. This protocol waived the usual retransmission overhead, to send files as fast as possible.
Originally, he wrote a program for Unix called rbsb (receive batch / send batch) which used block 0 to transmit a file's name, and optionally date and time, since Ward Christensen designed Xmodem to start at block 1, leaving block 0 available. At one point Ward, in a phone call to Chuck, suggested calling his protocol Ymodem because it was "one better" than Xmodem. Chuck created the program YAM which in traditional Unix nomenclature, stood for Yet Another Modem after "Modem.asm" the original version of Xmodem released by Ward in the CP/M User's group in 1977.
Forsberg most recently resided in Portland, Oregon prior to his death. He ran data transmission software company Omen Technology which he founded in 1984.[3] He was an amateur radio operator (call sign WA7KGX)[4] and a licensed aircraft pilot.[3]
Jesse Walker cited Forsberg as a participant in WMAS, a pirate radio station at Western Military Academy in Alton, Illinois.[5] He graduated from the academy in 1962.
References
- ^ a b "Charles Alton Forsberg obituary". Anewtradition.com. Retrieved October 10, 2015.
- ^ John C. Dvorak. "Dvorak Awards". Archived from the original on March 6, 2014. Retrieved December 8, 2010.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ a b "About Omen Technology". Archived from the original on September 15, 2015. Retrieved February 16, 2012.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ "Amateur License – WA7KGX – FORSBERG, CHARLES A". Retrieved February 16, 2012.
- ^ Walker, Jesse (2001). Rebels on the Air: An Alternative History of Radio in America. NYU Press. pp. 199, 305. ISBN 978-0-8147-9381-7.