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yugendran
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Joined: 14 Dec 2007
Posts: 51
Location: indore
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Hi Guys,
when/why we go for an assembler program if we can complete the same with other languages like COBOL etc.
If the answer is performance/efficiency, could you pls just elaborate on that with examples?
could you pls give me some examples where we have to use only assembler? ie the things which can't be handled by other languages..
Thanks,
Yuge |
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Garry Carroll
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Joined: 08 May 2006
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Location: Dublin, Ireland
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If you look at the LIST output from Cobol or PL/1, you can see how generalised the generated code is in certain areas. Writing in Assembler, you can avoid these generalisations and be more specific. This reduces the instruction path-length and this can improve run-time efficiency.
Some exits available in software packages must be written in Assembler, so if these are required you must code Assembler.
Garry. |
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PeterHolland
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Joined: 27 Oct 2009
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Location: Netherlands, Amstelveen
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| Accessing system control blocks is mostly done in assembler. |
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yugendran
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Joined: 14 Dec 2007
Posts: 51
Location: indore
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@Garry,
Thanks for the reply.. It would be very helpful if you pls explain the below point with example?
"If you look at the LIST output from Cobol or PL/1, you can see how generalised the generated code is in certain areas. Writing in Assembler, you can avoid these generalisations and be more specific. This reduces the instruction path-length and this can improve run-time efficiency."
Thanks again..  |
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Garry Carroll
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Joined: 08 May 2006
Posts: 1205
Location: Dublin, Ireland
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The pseudo-assembler from a PL/1 OPEN of a file
| Code: |
ST r1,_temp1(,r13,200)
L r1,MYFILE(,r6,8)
ST r1,_temp1(,r13,196)
ST r0,_temp1(,r13,192)
LA r0,_temp1(,r13,192)
L r15,=V(IBMQOFOP)(,r3,6)
LA r1,#MX_TEMP1(,r13,152)
ST r0,#MX_TEMP1(,r13,152)
BASR r14,r15 |
which involves a call to external routine IBMQOFOP compares with an assembler OPEN macro expansion
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+ CNOP 0,4
+ BAL 1,*+8
+ DC AL1(128)
+ DC AL3(MYFILE)
+ SVC 19 |
The generalisation is in the IBMQOFOP routine which caters for many file types.
The same holds true for many code expansions in high-level languages.
Garry. |
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yugendran
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Joined: 14 Dec 2007
Posts: 51
Location: indore
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| Thanks a lot Garry!!! It helps... |
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Robert Sample
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Joined: 06 Jun 2008
Posts: 8700
Location: Dubuque, Iowa, USA
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| One case where assembler comes in handy is when vendors are writing programs to access multiple files of different length records. COBOL, for example, requires at compile time that the record length be known since the FD must be completed. This information can be deferred to run time with assembler. |
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dick scherrer
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Joined: 23 Nov 2006
Posts: 19243
Location: Inside the Matrix
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Hello,
| Quote: |
| when/why we go for an assembler program if we can complete the same with other languages like COBOL etc. |
There are many "things" that assembler does and cobol and other high-level languages do not. . . Like the cases Peter and Robert mentioned along with the considerations from Garry.
Usually, assembler is not chosen when the program can be implemented using the "standard" application development language for the organization. There are fewer and fewer solid assembler people in the business  |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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| Quote: |
There are fewer and fewer solid assembler people in the business
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Yes Dick,
we (I) belong to a dying breed.  |
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enrico-sorichetti
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Joined: 14 Mar 2007
Posts: 10889
Location: italy
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we should apply UNESCO to be included in the protected world heritage treasures  |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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| enrico-sorichetti wrote: |
| we should apply UNESCO to be included in the protected world heritage treasures |
Absolutely Enrico,
but do we IT people fit in this "Social and Human Sciences" program? |
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dbzTHEdinosauer
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Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne
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| Quote: |
| "Social and Human Sciences" |
more likely, archeology  |
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