299:, IBM, however, refused to provide its PL/S compiler to customers, claiming it was a significant competitive advantage. Not having the compiler meant that neither competitors nor customers could modify the MVS code at the PL/S source level, and could only modify the generated assembler code. However, modifications made at the generated assembler level were easily obsoleted when IBM modified the PL/S source code and distributed re-generated assembler code. This was particularly true of modifications to PL/S generated data structures. Rand, therefore, decided to develop its own version of a PL/S compiler to meet both operational objectives and contractual commitments.
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of its licensed intellectual property is not known. The phase names of this PL/S compiler were the same as the corresponding phase names of IBM's PL/I Optimizer compiler, with the initial "I" (IBM) in each phase name being replaced by an initial "J" (Japan). All IBM copyright notices (source and object) within the modules were deleted to hide their true origin and ownership.
282:” was developed to allow Arpanet interrupts to be handled by specially written code while all other interrupts were handled by MVT. When the MVS operating system was announced by IBM, Rand volunteered as an early “beta” site for the operating system with the intent of porting the hypervisor and other modifications to MVS.
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A fully compliant PL/S compiler was "developed" by
Fujitsu Ltd in the late-1970s, adapting IBM's PL/I Optimizer compiler source code as its starting point. This PL/S compiler was used internally by Fujitsu, and also by Fujitsu's external affiliates. Whether or not IBM was aware of this unlicensed use
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W.R. Brittenham and B.F. Melkun, "The
Systems Programming Language Problem", Proceedings of the IFIP Working Conference on Machine Oriented Higher Level Languages, Trondheim, Norway, August 29–31, 1973, pp. 29–47. Amsterdam: North-Holland Publishing Co.; New York: American Elsevier, 1974. This
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language. This was assured by parsing many thousands of lines of IBM written PL/S code taken from the MVS distribution files. The assembler language code produced by the Rand RL/S compiler is not identical to the code produced by IBM’s PL/S compiler, but it is functionally equivalent.
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were distributed to attendees. IBM quickly responded claiming the language was “proprietary”. While Rand admitted no wrong doing in developing RL/S, Rand management agreed not to distribute the compiler publicly. Rand, however, continued to use the RL/S language and compiler
232:). The Rand RL/S compiler was developed independently of and without any assistance from IBM. Only publicly available, non-copyrighted PL/S documentation and PL/S source and generated assembler code examples from IBM distributed source files for the
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By the 1970s, IBM was rewriting its flagship operating system in PL/S. Although users frequently asked IBM to release PL/S for their use, IBM refused, saying that the product was proprietary. Their concern was that open PL/S would give competitors,
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PL/S was succeeded by PL/S II, PL/S III and PL/AS (Programming
Language/Advanced Systems), and then PL/X (Programming Language/Cross Systems). PL/DS (Programming Language/Distributed Systems) was a closely related language used to develop the
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vendors a competitive advantage. However, even though they refused to make available a compiler, they shipped the PL/S source code to large parts of the OS to customers, many of whom thus became familiar with reading it.
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and later converted to RL/S to improve performance. With few restrictions, RL/S programs could be developed using IBM’s PL/I compiler for preprocessing and debugging, with the final code then compiled by RL/S.
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As the market for computers and software shifted away from IBM mainframes and MVS, IBM recanted and has offered the current versions of PL/S to select customers (ISVs through the
Developer Partner program.)
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paper explores the technical and psychological problems encountered in implementing PL/S. The language and compiler are described. The discussion that followed presentation of the paper is included.
278:, including modifications to improve the performance of the Arpanet on its IBM 360 computer. Because MVT did not process network interrupts quickly enough to handle the Arpanet traffic, a “
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396:, International Business Machines Corp., 1974. GC28-6794-0 Note that this manual is very out of date with respect to the PL/X language in use today.
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was developed in the early 1970s by the
Computation Center of the Rand Corporation in Santa Monica, CA. It was implemented using the
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The Rand RL/S language and compiler were publicly announced in August, 1976, at a Share meeting where numerous copies of the
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359:, International Business Machines Corp., 1968, Z28-6642-0. Note that BSL was renamed PL/S and replaced by PL/S II
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Rand’s interest in PL/S derived from extensive modifications that the
Computation Center had made to IBM’s
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operating system, and PL/DS II was a port of the S/370 architecture for the DPPX/370 port.
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Closed PL/S meant that only IBM could easily modify and enhance the operating system.
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Rand has been a long-time contributor to computer research and development (e.g.,
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Proceedings of the SIGPLAN symposium on
Languages for system implementation 1971
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404:, The Rand Corporation, The Rand Computation Center, R-1555/11 1977
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compiler generator system by a team of three Rand programmers (
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RL/S announcement button distributed by Rand at Share 1976
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W.R. Brittenham, "PL/S, Programming
Language/Systems",
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on internal software projects; it included support for
263:). Rand was also one of the early nodes on the
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PL/S "please" button distributed by Share attendees
131:Early projects using PL/S were the batch utility,
46:but its sources remain unclear because it lacks
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267:, the Defense Department’s precursor to the
16:Proprietary IBM systems programming language
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302:The RL/S compiler was initially written in
366:, GUIDE 34, May 14, 1972, pp. 540–556
215:Rand RL/S compiler for IBM’s PL/S language
77:Learn how and when to remove this message
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239:RL/S is fully compatible with IBM’s
108:in the late 1960s, under the name
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418:PL/I programming language family
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401:RL/S Language Reference Manual
319:internally for many projects.
314:RL/S Language Reference Manual
157:Storage Technology Corporation
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433:IBM System/360 mainframe line
428:Systems programming languages
155:(National Advanced Systems),
94:Programming Language/Systems
356:BSL Language Specifications
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124:and explicit control over
165:Magnuson Computer Systems
116:), as a replacement for
32:This article includes a
61:more precise citations.
323:Fujitsu "Developments"
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228:, and the team leader
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199:Rand Compiler for PL/S
110:Basic Systems Language
104:. It was developed by
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343:High-level assembler
276:MVT operating system
234:MVS operating system
98:programming language
137:Time Sharing Option
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223:R. Lawrence Clark,
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34:list of references
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118:assembly language
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394:Guide to PL/S II
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122:inline assembly
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53:Please help
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378:John Ehrman
295:As is well
253:Rand tablet
236:were used.
59:introducing
412:Categories
349:References
297:documented
280:hypervisor
135:, and the
67:April 2010
100:based on
332:See also
269:Internet
126:register
265:Arpanet
241:PL/S II
173:Hitachi
169:Fujitsu
143:, TSO.
133:IEHMOVE
128:usage.
55:improve
257:WYLBUR
251:, the
149:Amdahl
384:, in
338:PL360
261:Baran
40:, or
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249:JOSS
213:The
189:DPPX
153:Itel
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90:PL/S
219:XPL
177:PCM
141:MVT
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