nbz wrote:My guess: it was meant to be a RESET pin, and when it's actually used as a RESET pin, it syncronizes component timings, thus eliminating the whole wakestate mess.
ijor wrote:Now, if you take control of this pin somehow, disconnect it from ground and attach it to some custom logic, you could change the wakeup at willing!
calimero wrote:So Atari was aware of wakestates but did not bother to fix this problem?
troed wrote:I've had an idea of creating a circuit that would read some output value of the ST and power cycle until it gets the "right" value - together with wakestate-detecting code in a bootsector. Thus allowing me to program a wanted wakestate value and then wait for the computer to happen into it.
calimero wrote:"Wakestate" consequence did not appear on ST users until invention of Spectrum512 technique for displaying more colors, right?
troed wrote:Actually "Spectrum 512 pixels" is another wakestate that I don't think is perfectly nailed down yet ...
The only "normal" ST operation affected by wakestates is that graphics is physically shifted as to the exact location on the screen So, if you were to pinpoint the exact placement of pixels on your monitor, you would see that it can be in four different locations, differing by one pixel from eachother.
ijor wrote:troed wrote:Actually "Spectrum 512 pixels" is another wakestate that I don't think is perfectly nailed down yet ...
That's something I yet have to test. I don't think I ever seen the issue.
What happens when it doesn't work? Does it happen on the actual Spectrum 512 program as well? Or only when you mix Spectrum 512 effects with full screen or syncscroll?
troed wrote:It's a persistent state (so, wakestate - power cycling is the only solution) where there's a pixels difference between graphics displayed on screen and when a palette change happens. So if you match palette changes vs graphics (like Spectrum 512 was the first to do) if you're pixel accurate in one state you might show black pixels in the other, the palette change hasn't "happened" when it "should". It happened with the release Spectrum 512 software, the manual basically said to power cycle if they happened.
(It's not because of ST wakestates DE-to-LOAD differences - the issue is the same on STE)
fpgaarcade wrote:It's used to speed up the H/V counter testing during production.
vertclk_test <= TEST xor VERTCLK
reset_test <= RESET and TEST
vs_cnt(1) <= not (XMDE1 and NTSC);
Users browsing this forum: No registered users and 4 guests