Hmm, it would be nice to have screen switching with QPC.

Malcolm


Derek Stewart wrote:
> Robert,
>
> When not put Minerva into your machine, then you will have a faster 
> operating system than JS or earlier and the second screen is working.
>
> Derek
>
> Robert Newson wrote:
>   
>> omega wrote:
>>
>>   
>>     
>>> Hello all,
>>>
>>> I want to present kind of "demo" for QL on the retro-computing 
>>> competition called Forever see: http://forever.zeroteam.sk
>>> I did some graphics already on PC and it looks good (looks cool in fact 
>>> :-). But, I need to write special screen hadler with following conditions:
>>>
>>> 1) I need to use both screens of the QL without affecting of the 2nd 
>>> screen by system variables.
>>> (if there must be some variables, how much is the minimum for 
>>> functionality interrupt handler?)
>>> 2) I still need to call my routine every interrupt (50/60Hz)
>>> 3) It must run on unexpanded QL with standard QDOS (sandyQboard 
>>> optional), no aurora, no Q40, Q60, no (S)GC. Plain, pure, virging QL only.
>>> 4) Safe return to Qdos is not required.
>>>     
>>>       
>>   
>>     
>>> Anyone has any idea if it's possible?
>>>     
>>>       
>> Have you/can you get your paws on a copy of the Advanced QL User Guide by 
>> Adrian Dickens (ISBN 0 947929 00 2)?
>>
>> On Pg 289-292 [of my copy] is a description of the second screen on the QL 
>> plus an assembler program to add pSeudoBASIC extensions to toggle the 
>> display.  It notes that the system variables splat over the top 1/5(ish) of 
>> the screen 1 and so keeps screen 0 displaying the top 1/5(ish) and then 
>> displays the required screen (0/1) for the bottom 4/5(ish).
>>
>> The active code allocates 0x6be0 bytes from the common heap which should be 
>> allocated in the memory screen 1 uses (to prevent any other program getting 
>> it).  It then uses a routine added to the 50/60Hz interrupt to switch 
>> screens as required.
>>   
>>     
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