PC/TCP Packet Driver: Difference between revisions

Revision as of 14:49, 23 March 2023

Revision as of 02:15, 11 August 2023

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A packet driver uses an [[INT (x86 instruction)|x86 interrupt number]] (INT) between {{nowrap|60h .. 80h.}} The number used is detected at runtime, it is most commonly 60h but may be changed to avoid application programs which use fixed interrupts for internal communications. The interrupt vector is used as a pointer (4-bytes [[Endianness|little endian]]) to the address of a possible interrupt handler. If the null-terminated ASCII text string "''PKT DRVR''" (2 spaces in the middle!) is found within the first 12-bytes -- more specifically in bytes 3 through 11 -- immediately following the entry point then a driver has been located.<ref>{{cite web |title=PC/TCP Version 1.09 Packet Driver Specification |url=http://cc.etsii.ull.es/ftp/antiguo/REDES2/doc/packet.txt |date=September 14, 1989 |access-date=2023-02-22 |publisher=FTP Software, Inc.}}</ref>

Packet drivers can implement many different network interfaces, including [[Ethernet]], [[Token Ring]], [[RS-232]], [[ARCNET|Arcnet]], and [[X.25]].<ref name="crpkt">{{cite web |title=PC/TCP Packet Driver Specification |url=http://www.crynwr.com/packet_driver.html |archive-date=November 27, 2022 |archive-url=https://web.archive.org/web/20221127060523/http://crynwr.com/packet_driver.html}} crynwr.com</ref>

== Functions ==