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Latest revision as of 13:54, 14 August 2023
स्क्वोज़ संक्षेपित रूप में संक्षेपित किया गया है जिसे एसक्यूजेड भी कहा जाता है एक मेमोरी-कुशल प्रतिनिधि है जो पंच्ड कार्ड पर सिम्बल टेबल के साथ संयुक्त स्रोत और स्थानांतरणीय ऑब्जेक्ट फ़ाइल प्रोग्राम की प्रतिनिधि है।[1][2] इसे 1958 में एसकैट असेंबलर के साथ आईबीएम 709 के लिए शेयर ऑपरेटिंग सिस्टम पर प्रस्तुत किया गया था।[3][4] इस फ़ॉर्मैट में एक प्रोग्राम को स्क्वोज़ डेक कहा जाता था। इसका उपयोग बाद में भी किए जाते थे, जिसमें आईबीएम 7090 और 7094 भी सम्मिलित थे।[5][6][7]
एन्कोडिंग
स्क्वोज़ एन्कोडिंग में, प्रतीक तालिका में पहचानकर्ताओं को 50-वर्ण वर्णमाला में दर्शाया गया था, जिससे 36-बिट मशीन शब्द छह अक्षरांकीय वर्णों और दो ध्वज बिट्स का प्रतिनिधित्व कर सके, इस प्रकार प्रति छह वर्णों में दो बिट्स की बचत हुई।[6][1]क्योंकि सामान्यतः प्रत्येक वर्ण के लिए आवंटित छह बिट्स वर्णमाला के 50 अक्षरों का प्रतिनिधित्व करने के लिए आवश्यक केवल 50 राज्यों के बजाय 64 राज्यों तक संग्रहीत कर सकते हैं, और 506<234.
स्क्वोज़ इंकोडिंग में, सिम्बल टेबल में पहचानकर्ताओं को एक 50-वर्णांतर के रूप में प्रतिनिधित किया गया था, जिससे एक 36-बिट मशीन वर्ड छ: अक्षरीय अंकों को प्रतिनिधित कर सकता था, और इसमें दो फ्लैग बिट्स थे, इसलिए प्रति छ: अक्षरों के लिए दो बिट बचाए जा सकते थे। यह इसलिए क्योंकि हर अक्षर के लिए सामान्यतः दिए गए छ: बिट स्थिति को 50 अक्षरों के प्रतिनिधित्व करने के लिए आवश्यक 50 स्थितियां स्टोर कर सकते थे, और 506 < 234।
| अधिकांश महत्वपूर्ण अंक | सबसे कम महत्वपूर्ण अंक | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Dec | +0 | +1 | +2 | +3 | +4 | +5 | +6 | +7 | ||
| Oct | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ||
| Dec | Oct | Bin | 000 | 001 | 010 | 011 | 100 | 101 | 110 | 111 |
| +0 | 0 | 000 | space | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
| +8 | 1 | 001 | 7 | 8 | 9 | A | B | C | D | E |
| +16 | 2 | 010 | F | G | H | I | J | K | L | M |
| +24 | 3 | 011 | N | O | P | Q | R | S | T | U |
| +32 | 4 | 100 | V | W | X | Y | Z | = # | / % | ) ⌑ |
| +40 | 5 | 101 | + & | - | - @ | + & | - | * | / | $ |
| +48 | 6 | 110 | , | . | — | — | — | — | — | — |
पहले से ही बेस 50 का उपयोग हर तीन अक्षरों में एक बिट बचाता है, इसलिए यह दो तीन-अक्षरीय टुकड़ों में उपयोग किया गया था। मैनुअल में छ: अक्षरों ABCDEF को इंकोड करने के लिए एक सूत्र है: उदाहरण के लिए स्क्वोज़,
सामान्यतः 36 बिट्स: 35 33 37 31 44 17(base 8) 34 बिट्स में फिट करने के लिए दो 17-बिट टुकड़ों में एन्कोड किया जाएगा ( 0o220231 << 17 ) | 0o175473 == 0o110114575473.
उसी तर्क का एक सरल उदाहरण यह होगा कि तीन अंकों वाला बाइनरी-कोडित दशमलव 12 बिट्स लेगा, जैसे कि 987: 9 8 7(base 16) 1001 1000 0111(base 2), परंतु ऐसे किसी भी मूल्य को सीधे 10 बिट्स में संग्रहीत किया जा सकता है, दो बिट्स को बचाते हुए, जैसे कि 987: 3db(base 16) 11 1101 1011(base 2).
व्युत्पत्ति
"स्क्वोज़" वर्ब "टू स्क्वीज़" का विनोदपूर्ण भूतकालीन भिन्नर्थक रूप है।[5][6]
बाद में डीईसी मशीनों पर इसी नाम को उपयोग करके समान योजनाओं को उधारा गया गया था। उनमें एक 40-वर्णांतर था और उन्हें डीईसी रैडिक्स 50 और MOD40 कहा गया था, लेकिन कभी-कभी उन्हें डीईसी स्क्वोज़ के नाम से भी जाना जाता था। [8]
यह भी देखें
- पैक्ड बीसीडी
- हर्ट्ज़ एन्कोडिंग
- चेन-हो एन्कोडिंग
- सघन रूप से पैक दशमलव
- बीसीडी
- बेस 50
- आधार रूपांतरण
संदर्भ
- ↑ 1.0 1.1 1.2 SHARE 709 System Committee, ed. (June 1961) [1959]. "Section 02: SCAT Language; Appendix 1: Table of Permissible Characters; Appendix 3: SQUOZE Deck Format - Chapter 8: Dictionary". SOS Reference Manual - SHARE System for the IBM 709 (PDF). New York, USA: SOS Group, International Business Machines Corporation. pp. 02.00.01 – 02.00.11, 12.03.08.01 – 12.03.08.02, 12.01.00.01. X28-1213. Distribution No. 1–5. Archived (PDF) from the original on 2020-06-18. Retrieved 2020-06-18. pp. 12.03.08.01 – 12.03.08.02:
[…] Bit Positions Used […] Bit 0 […] Bit 1 […] Bits 2–35 […] Base 50 representation of the symbol with heading character. […] The base 50 representation of a symbol is obtained as follows: […] a. If the symbol has fewer than five characters, it is headed (by blank if it is in an unheaded region). […] b. The symbol with it[s] heading character is left-justified and any unused low-order positions are filled with blanks. […] c. Each character in the symbol is replaced by it[s] base 50 equivalent. […] d. The result is then converted by the following: if the symbol, after each character is rep[l]aced by its base 50 equivalent, is ABCDEF, its base 50 representation is (A*502+B*50+C)*217+(D*502+E*50+F). […]
[1][2] - ↑ Salomon, David (February 1993) [1992]. Written at California State University, Northridge, California, USA. Chivers, Ian D. (ed.). Assemblers and Loaders (PDF). Ellis Horwood Series In Computers And Their Applications (1 ed.). Chicester, West Sussex, UK: Ellis Horwood Limited / Simon & Schuster International Group. ISBN 0-13-052564-2. Archived (PDF) from the original on 2020-03-23. Retrieved 2008-10-01. (xiv+294+4 pages)
- ↑ Jacob, Bruce; Ng, Spencer W.; Wang, David T.; Rodrigez, Samuel (2008). "Part I Chapter 3.1.3 On-Line Locality Optimizations: Dynamic Compression of Instructions and Data". Memory Systems: Cache, DRAM, Disk. The Morgan Kaufmann Series in Computer Architecture and Design. Morgan Kaufmann Publishers / Elsevier. p. 147. ISBN 978-0-12-379751-3. (900 pages)
- ↑ Jones, Douglas W. (2018). "Lecture 7, Object Codes, Loaders and Linkers - Final steps on the road to machine code". Operating Systems, Spring 2018. Part of the CS:3620 Operating Systems Collection. The University of Iowa, Department of Computer Science. Archived from the original on 2020-06-06. Retrieved 2020-06-06.
- ↑ 5.0 5.1 Boehm, Elaine M.; Steel, Jr., Thomas B. (June 1958). Machine Implementation of Symbolic Programming - Summary of a Paper to be Presented at the Summer 1958 Meeting of the ACM. ACM '58: Preprints of papers presented at the 13th national meeting of the Association for Computing Machinery. pp. 17-1–17-3. doi:10.1145/610937.610953. Archived from the original on 2020-06-06. Retrieved 2020-06-06. (3 pages)
- ↑ 6.0 6.1 6.2 Boehm, Elaine M.; Steel, Jr., Thomas B. (April 1959). "The SHARE 709 System: Machine Implementation of Symbolic Programming". Journal of the ACM. 6 (2): 134–140. doi:10.1145/320964.320968. S2CID 16545134. Archived from the original on 2020-06-04. Retrieved 2020-06-04. pp. 137–138:
[…] There is an interesting feature related to the encoding of symbols for inclusion in the dictionary. In the usual mode of expression, symbols may be constructed from a set of 50 characters. If encoding were character by character, six bits would be required for the representation of each such character. As a symbol may contain as many as six characters, a total of 36 bits would be required for the representation of each symbol. This might seem convenient, as the length of a 709 word is exactly 36 bits, but a moment's consideration shows that it is unfortunate as it would be desirable to have a bit or two available in the same word as the symbol representation, giving a clue to the nature of the symbol. These flagging bits can be obtained. Let each character possible represent a digit in a number system having a base of fifty. Now six character symbols may be read as natural numbers in a base fifty system. If these numbers are converted to the usual base two system, only 34 bits are required for the maximum number and a gain of two flag bits has been made. This has the incidental feature of decreasing the requisite number of bits for representing the entire code, but conversion time would outweigh the saving by a significant margin were it not for the peculiar length of the 709 word. Here is a clear illustration of the critical effect the precise specifications of the machine concerned hold over the details of an encoding schema. […]
{{cite journal}}: CS1 maint: unfit URL (link) (7 pages) - ↑ Shell, Donald L. (April 1959) [October 1958]. "The SHARE 709 System: A Cooperative Effort". Journal of the ACM. 6 (2): 123–127. doi:10.1145/320964.320966. S2CID 16476514. Archived from the original on 2020-06-16. Retrieved 2020-06-16.
{{cite journal}}:|archive-date=/|archive-url=timestamp mismatch (help) (5 pages) - ↑ "8.10 .RAD50". PAL-11R Assembler - Programmer's Manual - Program Assembly Language and Relocatable Assembler for the Disk Operating System (2nd revised printing ed.). Maynard, Massachusetts, USA: Digital Equipment Corporation. May 1971 [February 1971]. p. 8-8. DEC-11-ASDB-D. Retrieved 2020-06-18. p. 8-8:
[…] PDP-11 systems programs often handle symbols in a specially coded form called RADIX 50 (this form is sometimes referred to as MOD40). This form allows 3 characters to be packed into 16 bits […]
[3]
अग्रिम पठन
- Williams, Al (2016-11-22). "Squoze your data". Hackaday. Archived from the original on 2020-06-06. Retrieved 2020-06-06.
- Ehrman, John Robert; Snyder, James N. (1964-04-15). "3.3.2.1 SCAT". The PORTHOS Executive System for the IBM 7094 - User's Manual (PDF). University of Illinois, Graduate College Digital Computer Laboratory. Archived (PDF) from the original on 2020-06-07. Retrieved 2020-06-07.
[…] SCAT is a two part assembler which in brief operates as follows: Programs written symbolically as one order per card are ingested during the first phase by the "compiler" which scans the program for symbols and outputs a condensed deck of cards (SQUOZE deck) containing tables of these symbols and the program condensed and efficiently coded. During the second phase this SQUOZE deck is ingested by the "modify and load" program which converts the object program to binary machine language which by option can either be loaded ready to run or output on absolute binary cards (23 orders per card) for loading and running at a later time. The "lister" can produce a printed version of the program at either of these stages. Symbolic corrections to a program can be inserted into the second phase along with the SQUOZE deck. […]
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