[ih] "network unix"

[brian.e.carpenter at gmail.com (Brian E Carpenter)]

I don't recall a 6-bit byte notion in the PDP-8. The smallest addressable unit
was the 12-bit word, and the primary I/O device was an 8-bit ASR33 (which read
into bits 4 through 11 of the 12-bit accumulator, the 1966 manual reminds me).
Of course you could squeeze upper case ASCII down to 6 bits and store two
characters per word to save core memory; I expect I did that but this was 1969
so I don't quite remember.  Unlike some of my cohort, I didn't pad out my
dissertation by including source code, so it's long lost.

Regards
   Brian

On 10/10/2016 08:57, Jack Haverty wrote:
> Wow, people are actually reading this stuff...   Thanks to everyone who
> pointed out that PDP-8s didn't have 8-bit byte.  Tough audience...
> 
> What I meant to say was "PDP-8s had 12-bit words and IIRC some notion of
> 6-bit bytes.  PDP-11s had 8-bit bytes in 16-bit words"
> 
> Somewhere between brain and fingers my neural network must have dropped
> a packet......
> 
> /Jack
> 
> 
> On 10/09/2016 12:20 PM, Scott O. Bradner wrote:
>>
>>> On Oct 9, 2016, at 2:36 PM, Jack Haverty <jack at 3kitty.org> wrote:
>>>
>>> Hi Noel,
>>>
>>> You're right, I should have said 32KW....but I wonder how many people
>>> today would know what "KW" means?  I suspect many would think it
>>> referred to the power that our ancient monsters consumed...actually
>>> probably not far off for the bigger machines that consumed many square
>>> feet of lab space!
>>>
>>> The other aspect of the "Stone Age" that may not be remembered today is
>>> that a "byte" was not yet very well-defined back then.  PDP-8s had 8-bit
>>> bytes in 16-bit words.  
>>
>>
>> PDP-8s were 12 bit words
>>
>> PDP-1, 7, 9, 15 were 18 bit words
>>
>> PDP-11 were 16 bit words
>>
>> PDD 6, 10 were 36 bit words
>>
>> Scott
>>
>>> Other machines made different choices.  The
>>> PDP-10 was agnostic -- the instruction set allowed the programmer to
>>> specify whatever byte size they liked.  So a "byte" only made sense in
>>> the context of a specific machine.
>>>
>>> Today of course we all know that a byte is 8 bits.  Period.  Perhaps
>>> some historian can figure out exactly when that happened.....
>>>
>>> Fun times...
>>> /Jack
>>>
>>> On 10/09/2016 10:21 AM, Noel Chiappa wrote:
>>>> A few notes/corrections:
>>>>
>>>>> The /40 design utilized a single address space for instructions and
>>>>> data, so everything had to fit in 32KB of memory (yes K, not M or G).
>>>>
>>>> Err, that was 32KW, i.e. 64KB. But 8KB was the I/O page (device registers), so
>>>> only 56KB of memory - sort of, because V6 Unix used one 8KB page to map in
>>>> each process' kernel stack + other swappable per-process data, so really only
>>>> 48KB for all kernel code, data, disk buffers, etc.
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