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From: Evertjan. on 19 Jun 2010 04:31
Tim Streater wrote on 17 jun 2010 in comp.lang.javascript:

>> However it ment "swap registers a and b"
>
> Was it not "swap bytes" on an operand in the PDP-11? So you might say:
>
> swab R3 or swab (SP)
>
> for example to swap the bytes in register 3 or the top item on the stack.

This could be, tim,
as my connection at Philips in that era was a PDP-11 programmer.

If so, it was NOT an 2650 opcode. ;-(

=============

The problem of storng a word highbyte first or lowbyte first was a mayor
headache, so the operand was very useful, methinks.

I think Steve Morse of 8086 fame, now a mayor programmer for Ellis Island
files and Jewish geneology <http://stevemorse.org/>, wrote about that in
one of his books of the late 1970's?

No, not this one: <http://stevemorse.com/>

--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)
From: Andrea Giammarchi on 20 Jun 2010 06:43
just because nobody wrote any example like this one ...

var
a = 1,
b = 2
;

with ({swap:null}) {
swap = a;
a = b;
b = swap;
}

which can be shortcutted to:

with ({swap:a}) {
a = b;
b = swap;
}

another missed opportunity via one of the most misunderstood operator

Regards,
Andrea Giammarchi
From: Dr J R Stockton on 20 Jun 2010 14:35
In comp.lang.javascript message <timstreater-A97D44.21225919062010(a)news.
individual.net>, Sat, 19 Jun 2010 21:22:59, Tim Streater
<timstreater(a)waitrose.com> posted:

>In article <DmRh$GGjw9GMFwoo(a)invalid.uk.co.demon.merlyn.invalid>,
> Dr J R Stockton <reply1024(a)merlyn.demon.co.uk> wrote:
>
>> In comp.lang.javascript message <timstreater-150A94.10555217062010(a)news.
>> individual.net>, Thu, 17 Jun 2010 10:55:52, Tim Streater
>> <timstreater(a)waitrose.com> posted:
>>
>> >
>> >Was it not "swap bytes" on an operand in the PDP-11? So you might say:
>> >
>> > swab R3 or swab (SP)
>> >
>> >for example to swap the bytes in register 3 or the top item on the stack.
>> >
>>
>> Probably, since it is on page 10-13 of my copy of a handbook for the
>> LSI-11 series.
>>
>> Did you ever consider 014747, which is MOV -(PC),-(PC) ?
>
>Doesn't that cause your code to execute backwards, eating itself as it
>goes? Or something?

IIRC, it only creates, without eating. Each successive instruction
written is freshly written before the previous one. On a PDP-11,
hardware may stop it at address 0400 (?), but on an LSI-11 it may
overwrite the interrupt despatch area ...


--
(c) John Stockton, nr London UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
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