Editing PL/M (section)

==History==
Kildall was working at the [[Naval Postgraduate School]] in [[Monterey, California]] in 1973 when he received funds to equip a computer lab, first with [[MCS-4]]-based SIM4 and, a year later, the [[Intel 8008]]-based [[Intel Intellec 8]].{{sfn|Kildall|1993|p=48}} As part of his employment, Kildall was allowed to spend one day a week on his own projects, but soon found himself spending much more than that living in his [[Volkswagen Type 2|VW Microbus]] in the parking lot of the Intel offices on Bowers Avenue in [[Santa Clara, CA|Santa Clara]].{{sfn|Kildall|1993|p=49}}

One day he went to see Hank Smith, Intel's manager for the tiny microcomputer software department. Kildall explained his idea of making a [[high level language]] for the 8008. Smith didn't understand the concept, so Kildall explained that a programmer could write something like <code>X = Y + Z</code> and the program would convert that into several lines of [[assembler code]] which would perform this operation. Smith then called one of Intel's customers and asked if they might be interested in such a product, and when they expressed their interest, Smith immediately told Kildall to do it.{{sfn|Kildall|1993|p=49}}

Kildall wrote PL/M based on the concepts of the [[XPL]] language, which in turn was based on the syntax and concepts of [[IBM]]'s [[PL/I]]. XPL was explicitly designed to compile PL/I-like programs in a much simpler software system, explicitly for teaching purposes. As Kildall began promoting the language he found that few programmers were interested in it, until he demonstrated that one could write a program of roughly the same size and performance as assembly but in about a tenth of the time.{{sfn|Kildall|1993|p=49}}

PL/M originally ran on large [[PDP-10]] [[mainframe]] computers that would output the final [[machine language]] code on [[punch tape]] which would then be fed into an [[programmable ROM]] burner and then the ROMs would be transferred to the target machine. With the release of the Intellec 8 in 1974, he began an attempt to port the system to this platform to make it "self hosting" and allow programmers to do everything on that platform. Unfortunately, the 8008 had a very small eight entry [[call stack]] that was simply too small for a high-level language.{{sfn|Kildall|1993|p=50}}

This problem was solved with the introduction of the first [[Intel 8080]] in late 1973, which supported a stack of any size in memory.{{sfn|Kildall|1993|p=51}} Intel upgraded the Intellec 8 to the Intellec 8/80 based on the new chip. Although this system had the processing power to run PL/M, it lacked any useful form of [[mass storage]] and adding a useful amount of [[main memory]] was extremely expensive.{{sfn|Kildall|1993|p=52}} Just down the street from Intel, [[Memorex]] had recently introduced a new low-cost [[floppy disk]] drive,{{sfn|Kildall|1993|p=53}} and this in turn prompted [[Alan Shugart]] to start [[Shugart Associates]] and introduce lower-cost drives. Kildall was able to talk [[Finis Conner]], then at Shugart, into giving him one of their older test drives.{{sfn|Kildall|1993|p=54}}

Unfortunately, there was no [[drive controller]] for the Intel systems, and while one was sketched out it was never implemented. After sitting on a shelf for a year, Kildall decided to go ahead and write the software needed to use it in PL/M running on his 8080-emulator on the PDP-10. In 1974 he called a friend from the [[University of Washington]], John Torode, who built a controller for the 8080. After a few months the system was running, and Kildall loaded the driver and it ran the first time and displayed the prompt.{{sfn|Kildall|1993|p=55}}

During the summer of 1975, Kildall was working as a consultant at [[Signetics]], who asked him to port PL/M to their [[Signetics 2650]]. This resulted in the '''PLuS''' language. The 2650 "bombed" in the market and Signetics gave up on it within a year, deciding to license the [[Fairchild F8]] instead. While working there he met [[Jim Warren (computer specialist)|Jim Warren]], another consultant who was also setting up the new minicomputer-oriented magazine, ''[[Dr. Dobb's Journal]]''. Warren suggested Kildall put an ad in the magazine under the name of [[CP/M]], and this launched the system into the market.{{sfn|Kildall|1993|p=58}}