What is the BTCS instruction ?
Mark Smith
mark at SSD.HARRIS.COM
Wed Jan 30 05:11:41 AEST 1991
In article <9101241939.AA19540 at csd4.csd.uwm.edu> jgd at CSD4.CSD.UWM.EDU (John G Dobnick) writes:
>We received some code to fix a problem on our tahoe machine -- code
>which uses the BTCS instruction. While the assembler seems to know
>what this is, it is _not_ described in any of the manuals we have
>available. This makes it slightly difficult to understand just what
>the code is doing. (I believe we have the most current manuals our
>vendor supplies. This does not mean they are _really_ current, however.)
>
>My Question of the Day is:
>
> What is this BTCS instruction?
>
>Ideally, I seek a response that provides all the information that the
>architecture reference manual supplies for the other instructions --
>to wit, instruction format, operand specifications, description of
>operation, "pseudo code" description of the instruction, condition
>codes, etc.
>
Chapter 8 (Instruction Set) of the Harris Computer Systems Division
HCX-7 and HCX-9 Architecture Manual (Publication Number 0830022-100)
decribes the BTCS instruction as follows:
BTCS
BRANCH TO CONTROL STORE
Purpose: Custom design of new instructions
Format: opcode operand
Condition Code
Settings: N Z V C
Exceptions: None
Related Opcodes: 0xCE - Branch to WCS
Detailed Description: Branch to one of sixteen WCS locations. This
instruction allows the addition of customized
instructions for specialized functions.
Processing Details: Branch to one of sixteen unique WCS locations
pointed to by the last four bits of htet operand.
btcs()
/*********************************************/
/*BRANCH TO ONE OF SIXTEEN WCS LOCATIONS */
/*********************************************/
------------------------------------------------------------------------
That's it. Hope it helps.
>Thank you for whatever information you can supply,
>--
>John G Dobnick (JGD2)
>Computing Services Division @ University of Wisconsin - Milwaukee
>INTERNET: jgd at csd4.csd.uwm.edu ATTnet: (414) 229-5727
>UUCP: uunet!uwm!csd4.csd.uwm.edu!jgd
>
>"Knowing how things work is the basis for appreciation,
>and is thus a source of civilized delight." -- William Safire
Mark Smith
Internet: mark at flipper.csd.harris.com
UUCP: ...!uunet!travis!flipper!mark
Mark Smith
Internet: mark at flipper.csd.harris.com
UUCP: ...!uunet!travis!flipper!mark
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