[Simh] pdp11 and unix

[Timothe Litt]

On 27-Feb-16 14:57, Paul Koning wrote:
>> On Feb 27, 2016, at 2:49 PM, Bill Cunningham <billcun at suddenlink.net> wrote:
>>
>> Thanks much. Yes I know you were speaking of assembly. I was just considering history. I've always heard binary was first. What that might mean IDK. And there was no evidence presented for that.
> It may just be a case of people not familiar with early documents, extrapolating from the fact that early programming was in machine language and many early machines were binary.  In other words, overlooking the fact that the use of octal or even decimal would be a pretty natural choice even right at the beginning.
>
> 	paul
Binary, octal, hex - all the same thing.  Just how you group the bits.

I programmed on the switches (binary), but thought in octal.  Or Hex.

Mentally translating even the large PDP-10 or VAX instruction set to
binary is no more difficult than speaking a second language.  The
-8 and -11 are equivalent to baby talk :-)

I ended up doing this a lot during hardware debug, where the machine
didn't work well enough for debuggers with instruction decode to work.
(yet).  Easiest way to write a quick test or scope loop.

After a while I could look at a few instructions in memory near the PC and
tell where in the OS they came from.  My coworkers were amused (and
slightly frightened) when I told them where to look in the VMS listings, and
quoted the comments verbatim :-)

Before that, when machines had ASR33s for "mass storage", it was a whole
lot faster to debug and patch on the switches than to prepare an
error free source tape, load the assembler, load the tape twice (2-pass
assembler), punch the binary, load the binary - and check the results.

Not that assemblers and HLLs are bad things.  The environment dictates
what's feasible - and one should always use the right tool for a job.

Hitting a screw with a hammer may be cathartic, but the result isn't
optimal. 

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