[Info-vax] Assembly languages, was: Re: OT: PDP-11 history in arstechnica

[Johnny Billquist]

On 2022-03-17 01:48, Simon Clubley wrote:
> On 2022-03-16, Rich Alderson <news at alderson.users.panix.com> wrote:
>>
>> ALL the PDP-10 mnemonics for instructions which access memory have the same
>> form (taking MOVE as a canonical example):
>>
>> 	MOVE	load accumulator with contents of memory at effective address
>> 	MOVEI	load accumulator with immediate effective address calculation
>> 	MOVES	load accumulator with swapped halfwords of contents of memory
>> 		at effective address
>> 	MOVEM	store accumulator into memory at effective address
>>
>> Look at the last character of the instruction.  You don't even have to remember
>> the difference between "load" and "store".
>>
> 
> Doesn't anyone else find it strange that the mnemonic across all
> architectures is some variant of MOVE or MOV instead of COPY or CPY ?

You mean across all of these two (or three) DEC architectures (PDP-10, 
PDP-11 and VAX)?

Because some others use LOAD, LD, or some variant thereof. And then you 
have (as mentioned) the PDP-8 which only have TAD (two complement add), 
so if you want to read something out of memory, you better make sure the 
AC is 0 before you do. Which of course is helped by the store 
instruction which implicitly also clears the AC (DCA - Deposit and Clear 
AC).
And there are other things out there as well, if we talk about "all 
architectures".

   Johnny