[ih] "network unix"

[Jack Haverty]

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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