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IBM PC Network
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<h2 id="broadband">Broadband</h2> <p>The original <a href="/facts/Broadband/nEn3A95N">broadband</a> version in 1984 communicated over 75 Ω <a href="/facts/Cable_television/GzXa4pbW">cable television</a> compatible <a href="/facts/Co-axial_cable/aG9FfCpL">co-axial cable</a> with each card connecting via a single <a href="/facts/F_connector/XV88T6fV">F connector</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> Separate transmit and receive frequencies were used. Cards could be ordered that used different frequencies so multiple cards could transmit simultaneously, at 2 Mbit/s each.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> A Sytek head-end device was required to translate from each card's transmit frequency to the destination card's receive frequency. <a href="/facts/Frequency-division_multiplexing/lgj6TMU1">Frequency-division multiplexing</a> allowed the cable to be shared with other voice, video, and data traffic. </p> <h2 id="baseband">Baseband</h2> <p>Later, in 1987 a much cheaper <a href="/facts/Baseband/yC0jJwbL">baseband</a> version, also running at 2 Mbit/s connected computers in <a href="/facts/Daisy_chain_(electrical_engineering)/x1FsIB1E">daisy-chain</a> style using twisted-pair cables with <a href="/facts/6P2C/M3BYRSFV">6P2C</a> modular telephone connectors.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Interface cards had two 6P2C sockets for connecting to left and right neighbor nodes. The unused sockets at the ends of the network segment had to be fitted with a <a href="/facts/Electrical_termination/MatLrePo">terminator</a> on one end of the chain and a wrap plug on the other. A hybrid <a href="/facts/Star_topology/HPQDmFkI">star topology</a> was possible using a hub.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/LAN_Manager/JLXQQlGT">LAN Manager</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"IBM PC Network Interconnects IBM Personal Computers" (Announcement letter). IBM. 1984-08-14. <a href="https://www.ibm.com/docs/en/announcements/archive/ENUS184-100" target="_blank">https://www.ibm.com/docs/en/announcements/archive/ENUS184-100</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"IBM PC Network Program Available" (Announcement letter). IBM. 1985-04-02. <a href="https://www.ibm.com/docs/en/announcements/archive/ENUS285-132" target="_blank">https://www.ibm.com/docs/en/announcements/archive/ENUS285-132</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"IBM PC Network Interconnects IBM Personal Computers" (Announcement letter). IBM. 1984-08-14. <a href="https://www.ibm.com/docs/en/announcements/archive/ENUS184-100" target="_blank">https://www.ibm.com/docs/en/announcements/archive/ENUS184-100</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"IBM PC Network Adapter II/A-Frequency 2 And IBM PC Network Adapter II/A-Frequency 3" (Announcement letter). IBM. 1984-08-14. <a href="https://www.ibm.com/docs/en/announcements/archive/ENUS187-219" target="_blank">https://www.ibm.com/docs/en/announcements/archive/ENUS187-219</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Arst, Philip L. (22 June 1987). "Resolution Problems". Network World. Vol. 4, no. 25. p. 26. <a href="https://books.google.com/books?id=aR0EAAAAMBAJ&dq=ibm+baseband+lan&pg=PA26" target="_blank">https://books.google.com/books?id=aR0EAAAAMBAJ&dq=ibm+baseband+lan&pg=PA26</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"PC Network". <a href="https://www.ardent-tool.com/NIC/PC_Network.html" target="_blank">https://www.ardent-tool.com/NIC/PC_Network.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>