CompuServe Thread

Super72 800×600 is interlaced, even on AGA. It doesn't flicker as bad as NTSC 640×400 interlaced because it uses a 72-Hz refresh as opposed to a 60-Hz one. To get a non-interlaced AGA display, you need to use DblNTSC or DblPAL. You can also avoid flicker by using the non-interlaced resolutions of the other modes. For example, Super72 800×300 is not interlaced. To totally avoid flicker in all resolutions, a hardware de-interlacer is required. You should download the latest version of MonEd. It'll allow you to tweak sizes, positions, and frequencies of your monitor drivers. Also, see if you can get a copy of the 1942 setup disk. Although you don't have a 1942, the new monitor drivers, overscan prefs, and setpatch programs should help your situation. There is a fix on-line here for the vertical banding problem that some A1200's and A4000's suffer. It's an easy fix that's applied to the 23 to 15 pin adapter.

CH >>My problem is that in the higher resolutions there is some pretty bad flicker.<< What monitor drivers are you using? You can have high resolutions with both the NTSC & PAL drivers, BUT you need to use the Double-NTSC & Double-PAL drivers to have a higher refresh rate. The Double-NTSC, Double-PAL, Euro72, & Multiscan drivers, have a vertical refresh rates almost twice that of the NTSC, PAL, & Euro36 drivers. The Super72 driver, can generate a 800×300 screenmode with a vertical refresh rate of ~24-kHz (higher that NTSC, but lower than Multiscan), and a horizonal refresh rate of 72-Hz. The screen can be interlaced for a resolution of 800×600. — If the screen isn't properly centered, try using the Overscan program, located in the PREFS drawer. It will need to be used for each monitor driver. If that doesn't help, look on local BBS's for either "setp4014.lha" or "1942mon.lha", or "V39_update.lha", which contain updated versions of the monitor drivers, Overscan, and the Setpatch. — Selecting the "mode promotion" option of Icontrol, will inform the system that you want the Dbl-PAl & Dbl-NTSC drivers substituted for the PAL & NTSC screens. Icontrol doesn't work too well. Look in the Libraries for a program called "PPrefs.LHA". This is a promoter that works with most screens & resolutions, and it allows the user to select what screen types get promoted and what mode to promote them into. — CH >>Is this related to the software deinterlacing done on the A1200 as opposed to the hardware deinterlacing done on my A3000s?<< Yes, and no. In the past the hardware de-lacers for the Amiga, would convert ~15-kHz NTSC & PAL screens into ~31-kHz VGA screens. They captured the video data after the screen was generated, re-mixed it, and sent the video signal out at a higher rate. The Amiga's output hadn't changed, it was simply intercepted, and altered. The de-lacers expected to find only ~15-kHz video signals, and resolutions of 320 or 640 pixels wide, and 200 to 512 pixels tall. The AGA (& ECS) now outputs ~15-kHz, ~24-kHZ, ~31-Khz, with resolutions from 160 to 1280 wide, and 150 to 1024 pixels tall. De-lacing became a little more complicated. The A1200's (& A4000's) mode promotion feature attempts to identify what screenmode is being used, see if there is a alternative listed, then create that screenmode instead. There isn't any real de-lacing since the promotion allows skipping the generation of the laced version of the screen. Promotion, would be better described as a screenmode/resolution cross matching system for selecting one of many alternative screenmodes. — There are a few problems with the promotion. First, the system has to signaled, that you want a screenmode promoted. Programs that use a custom bootdisk, often will not include a way to activate the promotion. Second, the built-in promoter only bothers to promote a limited number of resolutions. This can be fixed by a third party promotion software, such as PPrefs. Third, there are programs whose graphics bypass the OS, preventing the promoter from substituting the requested screenmode for that program. These programs may be system friendly in every other way, but the OS's graphic system is blind to their existance. Ron. – ap'ing with AP. (Eagles may fly, but weasels aren't sucked into jet engines.)