magore@watdcsu.UUCP (03/13/87)
In article <634@sask.UUCP> long@sask.UUCP (Warren Long) writes: [munch...] >I have been toying with this idea for some time. I wrote a little >program on the atari 800 to screen-flip different intensities to the >screen and so create images with 4 grey levels, with 320 * 192 >resolution. Worked okay, but definate flicker. [munch...] >Warren Ok, I like all these ideas so I would like to offer a few of my own to add to the mix... With a very simple external bit of hardware [ or maybe software by playing with the display chips sync mode to confuse them for the correct ammount of time???] it would be possible to have 640*800 in high res and 640*400 color high res. Most monitors start the vertical sync sweep down the screen right after the release of vertical sync without concern for horizontal phase. If every other screen was delayed in the normal release of vertical sync by 1/2 half horizontal sync then you could interlace both screens just as normal TV does. On the mono-high-res this would work with much less flicker then a normal TV with NTSC would. [70hz!]. [ The frame rate would be twice as much ]. On color mode it would be the same with minor flicker , as on normal tv with near horizontal fine detail]. Also every other screen would have to display form two differing screen copies. [ New software drivers required though]. Oh yes, now turn your monitor on it's side and use as a full page display 800*640!?! Discarding the latter ideas of 800*640 we can do VERY fast scrolling 640*800 for full screen width displays. Here is how: Lose some memory and ORG each scan line [ or group of them ] MOD 256. Have the horizontal interrupt routine traverse a linked list so scrolling is a simple matter of altering a pointer! Imagine what UNITERM could do with this [ hint hint:) ]. Last idea. I have made a $20 video digitizer by running my cammera off the ST's sync and using the color high-res screen as a trigger source for a sample hold connected to an A/D. Start in the upper left hand corner and set/reset points top down and repeat left to right. 16 seconds later you have an image using the atari to replace most of the counting hardware you would normally need to do this. The whole set up works off the printer port and triggers off the red video output. [ It's works just great I have been using it for half a year now]. On using 5 1/4" drives don't forget to buffer the drive select and side select signals with open collector drivers and pull-up's. The drivers on the ST for those signals alone can not drive the termination packs in standard 5 1/4" drives... I use TEAC 80 track drives at the noramal ST step rate and they work just fine. I added a 37 pin D connector to the ST520 case above where the RF modulator isn't :) I used the same pin out as the 34 pin cable less 3 wires... [ I mention the drive type because not all 5 1/4" drives work at the fast rates so be careful... ] Best Regards, PS. I know some of ideas are simple and obvious to a few of you out there but if they were not and anyone finds them useful remember me when your rich :) Though I would make do with say a demo copy of course :) hint hint] # Mike Gore # Institute for Computer Research. ( watmath!mgvax!root - at home ) # These ideas/concepts do not imply views held by the University of Waterloo.