Date   : Tue, 01 Dec 2009 03:34:55 +0000
From   : kevin@... (Kevin Bracey)
Subject: Tube - I/O processor memory questions

Jonathan Graham Harston wrote:
>> Message-ID: <4B12E964.9040304@...>
>>     
>  
> Kevin Bracey wrote:
>   
>> Phew. Wrong information in the (New and original) Advanced User Guides
>> there. 
>>     
>  
> No. Nothing in "X points to a four byte zero page control block"
> (AUG p337) that says that it must be poked across the Tube into I/O
> memory.
No, it's the note on page 338 that's the problem...

> How do you think BASIC does PTR#?
>   
Well, it could have used the necessary OSWORD 5/6s. Didn't seem /that/ 
far-fetched to me having just spent ages faffing around using them 
trying to get my command-line across the Tube. (Or are you going to tell 
me that the command-line is automatically copied across in some way I've 
missed?) And I've seen more complex calls where data really does lives 
in the I/O processor - OSWORDs whose main blocks contain pointers to 
other blocks or strings.

Hmm, having just written that, I've just looked at the page yet again 
and maybe that's the point - there is OSARGS A=1,Y=0 there, which 
returns the pointer to the command line. Maybe they'd misinterpreted 
docs about that command line residing on the I/O processor, as it does, 
and ended up writing that note about the main control block.

Kevin