Annoying octal notation

Grant Edwards grante at visi.com
Sat Aug 22 16:08:09 CEST 2009


On 2009-08-22, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
> On Fri, 21 Aug 2009 10:45:51 -0700, John Nagle <nagle at animats.com>
> declaimed the following in gmane.comp.python.general:
>
>> 
>>      And it's over.  We can finally dispense with octal by default.
>>
> 	I've not looked at modern Intel processor format, but if there are
> folks still using variants of 8080 (8051?) and Z-80, Octal still works
> nice for op-codes... I don't recall the exact values, but the MOV
> instruction was something like '1SD'o, where S and D are three bit
> register specifications (A, B, C, D, E, H, L, and Memory as I recall)

The Heathkit's terminal I have uses a Z80, and IIRC, the
assembly listings were in split-octal [a 16 bit word ranges
from 000 000 to 377 377]. Stuff for the PDP-11 (which also had
instruction fields 3 bits wide) was always in octal as well.
The PDP-11 is pretty much dead, but I think there are embedded
Z80 derivitives still in use.

-- 
Grant




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