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Atari coding BBS
Re: STE stable fullscreen
Posted by: Troed Sep,02.2015-11:41 

I think it's important to try to have a consistent terminology here, but I'm not claiming to be authorative.

ST wakeup states: GLUE/CPU offsets (4 in total) - can be detected via software. These influence at which cycle you need to change registers. These are _fixed_ at boot and won't change with heat or clock migration or whatever you could think of.

ST & STE "Shifter modes": Offsets between GLUE+MMU & Shifter, or GST-MCU & Shifter, that influence several things. The most common being "banded screen" (known as every 16 pixels black, more information in my talk to come at STNICCC) and "striped horisontal lines" etc.

- the "striped horisontal lines" effect is due to the Shifter registers not being cleared and then next line then starts at a different position or is bitmap shifted etc. Is this what you mean with unstable lines? If so, then yes, even on STE this can happen and it's also a migratory state which means it can change during a single power on. Imagine this as the Shifter still being able to clear its registers everyone line even though your 186 byte lines are not divisable by 4 when the machine is "cold" - but when its "warm" it sometimes fails to clear all the words in the registers.

(I believe "Spectrum 512 dots" to be due to MMU/GST-MCU & Shifter desync in the rotation registers 32MHz clock vs the clock running LOAD, yet another cause and effect. This _might_ be a fix state set at boot. I hope to have time to present more info on this as well at STNICCC ... )

FWIW. I've never tried using STE hwscroll while manipulating line lengths so I don't know which of all these things match your "unstable" effect :)


[All messages in this thread]

Topic Posted by  Date 
STE stable fullscreen Leonard Aug,26.2015-16:10
  Re: STE stable fullscreen Patrice Mandin Aug,27.2015-16:45
    Re: STE stable fullscreen evil Aug,27.2015-18:07
      Re: STE stable fullscreen Leonard Aug,27.2015-18:19
        Re: STE stable fullscreen evil Aug,27.2015-18:38
          Re: STE stable fullscreen Leonard Aug,28.2015-09:26
            Re: STE stable fullscreen evil Aug,28.2015-10:27
              Re: STE stable fullscreen Patrice Mandin Aug,28.2015-18:43
                Re: STE stable fullscreen Leonard Aug,28.2015-20:55
                  Re: STE stable fullscreen Patrice Mandin Aug,29.2015-10:17
                    Re: STE stable fullscreen Leonard Aug,29.2015-10:23
                      Re: STE stable fullscreen Patrice Mandin Aug,29.2015-15:42
                        Re: STE stable fullscreen Bod/Effect Sep,29.2015-16:53
  Re: STE stable fullscreen Troed Sep,02.2015-11:41
    Re: STE stable fullscreen Troed Sep,02.2015-12:08

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