Charles Alton "Chuck" Forsberg (May 6, 1944 – September 24, 2015) developed two

data transmission Data communication, including data transmission and data reception, is the transfer of data, signal transmission, transmitted and received over a Point-to-point (telecommunications), point-to-point or point-to-multipoint communication chann ...

protocols popular in the 1990s, for

upload Uploading refers to ''transmitting'' data from one computer system to another through means of a network. Common methods of uploading include: uploading via web browsers, FTP clients, and terminals ( SCP/ SFTP). Uploading can be used in th ...

ing and

download In computer networks, download means to ''receive'' data from a remote system, typically a server such as a web server, an FTP server, an email server, or other similar systems. This contrasts with uploading, where data is ''sent to'' a remote ...

ing files from dial-up

bulletin board system A bulletin board system (BBS), also called a computer bulletin board service (CBBS), is a computer server running list of BBS software, software that allows users to connect to the system using a terminal program. Once logged in, the user perfor ...

s. He received a Dvorak Award for Excellence in Telecommunications in 1992 for developing ZMODEM. He was also the project engineer on the

Tektronix 4010 The Tektronix 4010 series was a family of text-and-graphics computer terminals based on storage-tube technology created by Tektronix. Several members of the family were introduced during the 1970s, the best known being the 11-inch 4010 and 19-in ...

-series graphics terminals. The widely adopted ZMODEM uses a sliding window protocol. Rather than wait for positive acknowledgment after each block is sent, it sends blocks in rapid succession and resends unacknowledged blocks later. By avoiding delays due to latency, the bandwidth usable for transmission more closely approached the

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

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 Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

for sending and receiving files using ZMODEM. Forsberg 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 Ward Leon Christensen (October 23, 1945 – October 11, 2024) was an American computer scientist who was the inventor of the XMODEM file transfer protocol and a co-founder of the CBBS bulletin board, the first bulletin board system (BBS) ever br ...

designed

XMODEM XMODEM is a simple file transfer protocol developed as a quick hack by Ward Christensen for use in his 1977 MODEM.ASM terminal program. It allowed users to transmit files between their computers when both sides used MODEM. Keith Petersen made a ...

to start at block 1, leaving block 0 available. Christensen suggested Forsberg call his protocol

YMODEM YMODEM is a file transfer protocol used between microcomputers connected together using modems. It was primarily used to transfer files to and from bulletin board systems. YMODEM was developed by Chuck Forsberg as an expansion of XMODEM and was f ...

because it was "one better" than Xmodem. Forsberg created the program ''YAM'', which in traditional Unix nomenclature stood for ''Yet Another Modem'' after "Modem.asm", the original version of Xmodem released by Christensen in the CP/M User's group in 1977. Forsberg most recently resided in

Portland, Oregon Portland ( ) is the List of cities in Oregon, most populous city in the U.S. state of Oregon, located in the Pacific Northwest region. Situated close to northwest Oregon at the confluence of the Willamette River, Willamette and Columbia River, ...

, prior to his death. He ran data transmission software company Omen Technology which he founded in 1984. Omen Technology published software tools such as ZComm (a terminal-based communications program that included the ZMODEM-90 file transfer protocol) and DSZ. He was an

amateur radio operator An amateur radio operator is someone who uses equipment at an amateur radio station to engage in two-way personal communications with other amateur operators on radio frequencies assigned to the amateur radio service. Amateur radio operators ...

(call sign WA7KGX) and a licensed aircraft pilot. OmenTechnology-ZComm-DSZ-SoftwareDisks

Jesse Walker cited Forsberg as a participant in WMAS, a

pirate radio station Pirate radio is a radio station that broadcasts without a valid license, whether an invalid license or no license at all. In some cases, radio stations are considered legal where the signal is transmitted, but illegal where the signals are rec ...

at Western Military Academy in

Alton, Illinois Alton ( ) is a city on the Mississippi River in Madison County, Illinois, United States, about north of St. Louis, Missouri. The population was 25,676 at the 2020 United States census, 2020 census. It is a part of the River Bend (Illinois), Riv ...

. He graduated from the academy in 1962.

References

{{DEFAULTSORT:Forsberg, Chuck 1944 births 2015 deaths Amateur radio people American computer programmers American electrical engineers Aviators from Illinois