Re: A86: the 0 port
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Re: A86: the 0 port
The grayscale asm pictures use the 0 port. Port 0 is used for changing the
address of the 1024 byte memory mapped region that the display is showing.
You can look at that source.
Instead of $FC00, for example, you can change it to something else. The only
uses I can see it for is for double buffering and grayscale... I am still
studying the grayscale src though, so....
-Matt
>Can somebody explain exactly how the 0 port is used? The 86ports.txt
>isn't much help.
>---
>Andy Johnson
>"Change is inevitable...
> except from vending machines"
>
>On Tue, 17 Mar 1998 14:43:11 +0100 Robert Niedziela <meth@friko2.onet.pl>
>writes:
>>
>>I have that same problem, changing display memory every 5 interrupts
>>is minimum, but it starts to flick.
>>
>>KIRK MEYER wrote:
>>
>>> hello. i finally realized i was unsubscribed. i have a question
>>about port 0. i know it switches the memory that the screen displays,
>>but there are some funny things about it. when the port is alternated
>>every other interrupt routine, nothing happens. is the screen updated
>>every OTHER interrupt? if you switch it every four, it does something,
>>and it does something very odd with lots of lines going down the
>>screen. if you switch it every six or eight, it works but flickers way
>>to much. any help is appreciated.
>
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