“G,” either alone or in “GF,” in their mnemonics



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“G,” either alone or in “GF,” in their mnemonics

Postby BillW » Fri Nov 11, 2011 8:11 pm

I have only started to look at the Principle of Ops/ Z-Arch. Does the "G" or "GF" have a meaning, like Gosh, GoshFarkle. I sure I will eventually find this, but thought it would be could to know before I digest this 1400 page behemoth. TIA.
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Re: “G,” either alone or in “GF,” in their mnemonics

 

Re: “G,” either alone or in “GF,” in their mnemonics

Postby enrico-sorichetti » Fri Nov 11, 2011 8:21 pm

I have only started to look at the Principle of Ops/ Z-Arch. Does the "G" or "GF" have a meaning,
:shock:
they might have it ...
if You want good answers please learn to ask good questions...

if You tell which instruction is giving You this headache, or where in the manual You fund such distressing letter combination
it would be faster for us to give You a good reply :geek:

I remember that at the beginning the instructions dealing with 64 bits <things> were called GRANDE instructions
but that' s just a wild guess

the only one that know will just the IBM IT developers
cheers
enrico
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Re: “G,” either alone or in “GF,” in their mnemonics

Postby enrico-sorichetti » Fri Nov 11, 2011 8:37 pm

follow on...
anyway the instruction mnemonics just bear similarities to the real <actions> only marginally

AGF might hint an addition dealing with Grande(64 bits) and Full (32 bits ) values, but ... beware

but then all the mnemonics should be checked for consistency
and that' s just a wild guess knowing the warped mind of some IBMers

look at the mnemonics where the G and the GF appear and carry on the appropriate associations
cheers
enrico
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Re: “G,” either alone or in “GF,” in their mnemonics

Postby BillW » Sat Nov 12, 2011 5:39 am

Enrico,

Thanks, but the purpose of a mnemonic is to help you remember. Hence L, LA, LM, LR all do a Load of one sort or another. I could give you bunches of examples of this, but I don't think you need that. What I would like to know precisely is this, does the "G" or the "GF" that have been included have such a mnemonic meaning? You indicate "Grande" as an example. Is this of your own design? or has it been found in an IBM manual? (if so, which one) Often, having the real meaning of the letter(s) is helpful in understanding it's use.

Oh, just as aside, I wrote my first ibm bal program for a 360 in 77. Thank you very much.
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Re: “G,” either alone or in “GF,” in their mnemonics

Postby dick scherrer » Sat Nov 12, 2011 12:32 pm

Hello,

What I would like to know precisely is this, does the "G" or the "GF" that have been included have such a mnemonic meaning?
If you post a few of these, it will help someone clarify for you. . . I'm not sure which instructions you are asking about :?

Oh, just as aside, I wrote my first ibm bal program for a 360 in 77.
Ah, kinda new are ya. . . 8-)
Hope this helps,
d.sch.
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Re: “G,” either alone or in “GF,” in their mnemonics

Postby enrico-sorichetti » Sat Nov 12, 2011 2:02 pm

Thanks, but the purpose of a mnemonic is to help you remember.

That' s the general idea, but it' s effectiveness usually depends on the associativity capability of the users neurons
and when the number of abbreviations grows the objective gets more difficult to achieve

Hence L, LA, LM, LR all do a Load of one sort or another. I could give you bunches of examples of this, but I don't think you need that.
What I would like to know precisely is this, does the "G" or the "GF" that have been included have such a mnemonic meaning?
depends of what You intend for precise and mnemonic...

if You had read and meditated a few seconds on the paragraph
General Instructions for 64-Bit Integers
( in page 1-2 of the z/Architecture Principles of Operation SA22-7832-08 )

The 32-bit-binary-integer instructions of ESA/390
have new analogs in z/Architecture that operate on
64-bit binary integers. There are two types of analogs:
• Analogs that use two 64-bit binary integers to
produce a 64-bit binary integer. For example, the
ESA/390 ADD instruction (A for a storage-to-register
operation or AR for a register-to-register
operation) has the analogs AG (adds 64 bits from
storage to the contents of a 64-bit general register)
and AGR (adds the contents of a 64-bit general
register to the contents of another 64-bit
general register). These analogs are distinguished
by having “G” in their mnemonics.
• Analogs that use a 64-bit binary integer and a
32-bit binary integer to produce a 64-bit binary
integer. The 32-bit integer is either sign-extended
or extended on the left with zeros, depending on
whether the operation is signed or unsigned,
respectively. For example, the ESA/390 ADD (A
or AR) instruction has the analogs AGF (adds 32
bits from storage to the contents of a 64-bit general
register) and AGFR (adds the contents of bit
positions 32-63 of a 64-bit general register to the
contents of another 64-bit general register).
These analogs are distinguished by having “GF”
in their mnemonics.

You would have had no need to ask ...

but if You do not trust the IT developer and You want to double check
You will have to go thru all the instructions with the G and the GF and check accordingly

You indicate "Grande" as an example. Is this of your own design?
stupid remark/question when I answer I always check that reasonable evidence exists

if You had googled for 'grande instructions' You would have found quite a few references
SHARE presentations, Assembler manuals from Tachyon and Dignus,
unfortunately, unless I missed something, nothing explicit IBM
Often, having the real meaning of the letter(s) is helpful in understanding it's use.
as said before ... depends on the associativity capability of the users neurons
and on having read and understood the above quoted paragraph
Oh, just as aside, I wrote my first ibm bal program for a 360 in 77

irrelevant to the discussion, i did that quite a few years before that
such a long experience should have warned You on the obscure ways of IBM
but on the other side the quote from the manual is not that obscure

if you post a few of these, it will help someone clarify for you. . . I'm not sure which instructions you are asking about

Dick! seems to me that the gentleman is just arguing about the G and GF <mnemonicity> :geek:
cheers
enrico
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Re: “G,” either alone or in “GF,” in their mnemonics

Postby dick scherrer » Sun Nov 13, 2011 10:04 am

Hi Enrico,

As often happens, i came late to the party. . . :)

seems to me that the gentleman is just arguing about the G and GF <mnemonicity>
I wasn't sure what was actually the question :oops:

Many neurons fried and few replacements in sight.

Later,

d
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