[Coco] technical assembler question

[Bob Devries]

Robert Gault said:
> Probably depends on how often your code will do the BREAK test. You would 
> not want several seconds to go by but the user is not likely to notice the 
> difference of a poll every second vrs VSYNC intervals.

To do a break check on the VSYNC interrupt would mean I'd need to write a 
bit of code to enable the VSYNC interrupt, and catch it, am I right?
Then I would still need to do a check if in fact the break key had activated 
my interrupt routine. My programme is I/O intensive (reading a disk), but it 
seems slow to respond to the break key (at least in MESS).

--
Regards, Bob Devries, Dalby, Queensland, Australia

Isaiah 50:4 The sovereign Lord has given me
the capacity to be his spokesman,
so that I know how to help the weary.

website: http://www.home.gil.com.au/~bdevasl
my blog: http://bdevries.invigorated.org/

----- Original Message ----- 
From: "Robert Gault" <robert.gault at worldnet.att.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Thursday, May 17, 2007 11:37 AM
Subject: Re: [Coco] technical assembler question


> Bob Devries wrote:
>> dear friends,
>>
>> I'm doing some writing in assembler for RSDOS (DECB). I don't do this 
>> often, you understand, so I've got a question:
>>
>> When checking for a BREAK key, is it necessary yo do multiple reads of 
>> the POLCAT routine to ensure the key is not missed? At the moment i have 
>> this code:
>>
>> jsr [POLCAT]
>> beq dskcont ;no key pressed, continue
>> cmpa #BREAK ;that's #$03
>> bne dskcont ;on BREAK, fall through to exit routine
>>
>> Should I loop through that a few times to be sure I don't miss it or will 
>> that slow the programme down too much.
>>
>> What do the "experts" do in this case?
>>
>
> Probably depends on how often your code will do the BREAK test. You would 
> not want several seconds to go by but the user is not likely to notice the 
> difference of a poll every second vrs VSYNC intervals.
>
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