IBM Mainframe Forum

[ramachandran]

what are the pseudo instructions available in assembler?

[William Thompson]

what are the pseudo instructions available in assembler?

I waited to see if anybody had any idea of what you meant by "pseudo instructions", but I guess everybody else is just a mystified as I am.......

Try again, are you referring to the "PLx" stuff the supervisor/nuclease is coded in? Or just macros?

[dick scherrer]

Hello and welcome to the forum,

Might you mean macro instructions rather than pseudo?

Pseudo-code/instructions are often used to demonstrate logic so that something may explained rather than implemented in some specific instruction set.

[hlasm1]

EQU is an example of pseudo instruction in assembler. Pseudo instructions are never categorised as RR,RX,RS,SS1,SS2,Si instructions. Pseudo instructions do not occupy memory like A,AR and so on.

[dick scherrer]

Hello and welcome to the forum,

I believe the term you are describing is a pseudo-operation:

A pseudo-operation, commonly called a pseudo-op, is an instruction to the assembler that does not generate any machine code. The assembler resolves pseudo-ops during assembly, unlike machine instructions, which are resolved only at runtime. Pseudo-ops are sometimes called assembler instructions, assembler operators, or assembler directives.

Additonal info is available here:
http://www.nersc.gov/vendor_docs/ibm/as ... _ovrvw.htm

[billyy2288]

Hello and welcome to the forum,

I believe the term you are describing is a pseudo-operation:

A pseudo-operation, commonly called a pseudo-op, is an instruction to the assembler that does not generate any machine code. The assembler resolves pseudo-ops during assembly, unlike machine instructions, which are resolved only at runtime. Pseudo-ops are sometimes called assembler instructions, assembler operators, or assembler directives.

Additonal info is available here:
http://www.nersc.gov/vendor_docs/ibm/as ... _ovrvw.htm

Such a very amazing link!

[steve-myers]

The HLASM Language Reference does not use either term "pseudo operation" or "pseudo instruction." I must admit I was surprised! HLASM calls them "assembler instructions," and defines several types. Taken as a generic, a "pseudo operation," "pseudo instruction, or "assembler instruction" refers to Assembler code that appear to be a machine code but serve other purposes. Many Assemblers have a REM pseudo instruction to define a comment, but HLASM does not define such an animal in the manual.

• Program control - AINSERT, CNOP, COPY, END, EXITCTL, ICTL, ISEQ, LTORG, ORG, POP, PUNCH, PUSH, and REPRO.
• Listing control - CEJECT, EJECT, PRINT, SPACE and TITLE.
• Operation code definition - OPSYN
• Program section and linking - ALIAS, AMODE, CATTR, COM, CSECT, CXD, DSECT, DXD, ENTRY, EXTERN, LOCTR, RMODE, RSECT, START, WXTRN and XATTR.
• Base register - DROP and USING.
• Data Definition - CCW, CCW0, CCW1, DC and DS.
• Symbol definition - EQU.
• Associated data - ADATA.
• Assembler options - *PROCESS (Since *PROCESS starts in column 1, arguably it's not a pseudo instruction), ACONTROL.

I have to admit I've never used many of these; I'm just copying them from the HLASM Language Reference.