Date   : Sun, 29 Nov 2009 23:51:49 +0100
From   : kortink@... (John Kortink)
Subject: Tube - I/O processor memory questions

On Sun, 29 Nov 2009 21:57:15 +0000, Kevin Bracey
<kevin@...> wrote:

>John Kortink wrote:
>> On Sun, 29 Nov 2009 21:36:36 +0000, Kevin Bracey
>> <kevin@...> wrote:
>>
>>
>>   
>>> Phew. Wrong information in the (New and original) Advanced
>>> User Guides there. [...]
>>>     
>>
>> That's probably a matter of interpretation ...
>>   
>Did you read it before making that comment?

Perhaps sadly, I didn't need to. I knew exactly what
you were referring to.

>Unlike all the other OS calls, it explicitly says for OSARGS
>
>"Note: the control block always resides in the I/O processor's memory, 
>regardless of the existence of a Tube processor."
>
>I'd be intrigued to see how you interpret that as "Note: the control 
>block lives in the current processor just like any other OS call, so I 
>don't know why we bothered writing this note, to be honest."

I wouldn't say the comment is not confusing, but I
always considered it to be made in the vein that,
clearly, if you specify only one byte of an address
it can't explicitly refer to second processor memory.
While with four, it can (which is explicitly stated
here and there as well).

In a strict sense, the comment applies to all addresses
which are less than four bytes long. It just forgets to
mention that the copying to I/O memory is done for you,
if necessary ...


John Kortink

-- 

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