[Info-vax] OT: PDP-11 history in arstechnica

[Rich Alderson]

chris <chris-nospam at tridac.net> writes:

> On 03/15/22 01:22, Simon Clubley wrote:
>> On 2022-03-14, Bob Gezelter<gezelter at rlgsc.com>  wrote:
>>> On Monday, March 14, 2022 at 7:47:34 PM UTC-4, Arne Vajhøj wrote:
>>>> https://arstechnica.com/gadgets/2022/03/a-brief-tour-of-the-pdp-11-the-most-influential-minicomputer-of-all-time/

>>> Arne,

>>> Not sure where the author of the arstechnica piece saw "$" for immediate
>>> mode, e.g., mov $10,r0. MACRO-11 as I new it, always used a "#", e.g., MOV
>>> #SS.XYZ,R0.

>>> Spent lots of time writing and generating assembler for RSX-11 systems and
>>> relatives, e.g., P/OS. Did many interesting things.

>>> - Bob Gezelter, http://www.rlgsc.com

>> DEC versus AT&T syntax (and yes, I know the following is Intel not DEC,
>> but it's much the same thing here for the syntax you mention):

>> https://wiki.osdev.org/Opcode_syntax

>> Perfectly normal and expected. Also note "mov src, dest" instead of
>> "mov dest, src".

> Yes, from, to, left to right. Same for 68000 series as well. Intel
> always were a bit backward in that respect...

>> Expect to see more of it in your future. :-)

"DEC" syntax, hmm?  Macro-10:

	MOVE 17,SUMWHR
	ADDI 17,37
	MOVEM 17,ELSWHR

The "destination" AC always follows the opcode immediately, the effective
address of the "source" comes after the comma.  Note that since there are
"to-memory" instructions, the notion of "source" vs. "destination" is not
particularly useful...

-- 
Rich Alderson					  news at alderson.users.panix.com
      Audendum est, et veritas investiganda; quam etiamsi non assequamur,
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									--Galen