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Text File | 1994-08-25 | 13.0 KB | 284 lines

MPATCH - The Monitor Patch Utility, V37.9 ========================================= WHY MPATCH? ----------- Some time ago, I upgraded my old A2000 with the latest Denise revision since I do a lot of writing and DTP on my AMIGA, and that 50 Hz PAL display started to hurt my eyes. The MULTISCAN mode was better, but my C1960 monitor seemed to have problems sync'ing on the 60 Hz signal: the picture was always stretched vertically, so I had to switch to MANUAL and adjust the vertical size manually. However, the PAL mode was then squeezed vertically, resulting in a very odd aspect ratio; so I had to switch from MANUAL to AUTO and back every time a program came up with a PAL screen. The EURO72 mode introduced with V38 was a bit better but its 640 x 400 screen tended to become quite crowded once I had one or two CLI windows and the SE window open on it. Also some older software, like the famous PowerPacker, would always open a 60 Hz Productivity screen - so it had to be Multiscan (and switching manually) again. Then, one day, I scanned my C include files in search of some struct definition, and came across the monitor.h file, spotted the word VSYNCTRUE somewhere, and the rest was history. I had already toyed with various sync settings on a graphics card, and so I knew that some monitors (like the C1960) use the polarity of the sync signals to determine the aspect of the video signals they receive. I just had no idea that the ECS chipset supports positive sync signals as well. All I had to do is to find out where the BeamCon0 values are stored, and then write this small program. As I tested it, I found some other goodies to include, and so MPATCH grew ... USAGE ----- MPATCH can only be run from the CLI or Shell. MPATCH <monitor-name> [HSYNCTRUE][VSYNCTRUE][SYNCTRUE][HSYNCFALSE] [VSYNCFALSE][SYNCFALSE][LOLDIS][HSYNCDELAY <delay>] [VSYNCDELAY <delay>][HSYNCLEN <len>][VSYNCLEN <len>] <monitor-name> is the name of the monitor to be patched, e.g. "multiscan.monitor" or just "multiscan". Upper/lowercase is important. V37 (2.0) and V38 (2.1) monitor names are all in lower case; the new modes introduced with V39 (3.0), however, are mixed case. You must type "DoublePAL" or "DoubleNTSC" in order that these names be recognized. HSYNCTRUE - changes the horizontal sync signal's polarity to positive, or "true" (1) logical level. By default, all monitors have their syncs set to negative, or "false" (0) logical level. VSYNCTRUE - changes the vertical sync signal's polarity to positive, or "true" (1) logical level. By default, all monitors have their syncs set to negative, or "false" (0) logical level. SYNCTRUE - this is just a shortcut for HSYNCTRUE VSYNCTRUE; so if you specify SYNCTRUE, both syncs are switched to "true" (see above for details) HSYNCFALSE, VSYNCFALSE, SYNCFALSE - these are the counterparts to the ...SYNCTRUE switches listed above. The horizontal, vertical, or both sync signals are set to "active low", which is the default for all monitors from V37 (V2.04) to V39 (V3.0) of the AMIGA OS. LOLDIS - means "LOng LIne DISable". On the "non-native" video mode (PAL on NTSC machines, NTSC on PAL machines), every second scanline is a "long line" due to DMA timing restrictions. (The exact length of a PAL video scanline would be 227.5 DMA cycles per line. Since 0.5 cycles are impossible for the hardware, every second scanline is displayed with a length of 228 cycles, hence the name "long line"). This flag is set by default for all nonstandard ("VGA") modes. It should be set for the NTSC mode on PAL AMIGAs as well, at least if you are using "BBlank" or a similar utility that enables border blanking; otherwise the right border might look a bit wobbly. The following options can only be used with VGA/Multiscan modes, and will be ignored if used with the PAL or NTSC modes. The <delay> and <len> values for HSYNCDELAY and HSYNCLEN all in 280 ns "ticks" (the exact interval depends on whether you are using a PAL or NTSC machine.) NOTE for users of versions V37.7 and below! The behaviour of the HSYNCDELAY and VSYNCDELAY options has been changed damatically. The <delay> value is now an absolute offset from the start of the blanking interval rather than relative to the current settings. Negative values are no longer allowed. Do not install this version (V37.9) if the old version produced good results. There is absolutely no point in doing so, just a lot of extra work. NOTE: Do not use any of these keywords if you have installed AmigaOS 3.1, as this release has the ability to adjust the image position built into the Overscan editor. HSYNCDELAY <delay> - Modifies the position of the horizontal sync pulse in the horizontal blanking period. The <delay> is an offset from the start of the horizontal blanking period, and must lie between 0 and 18. If you specify a value that is out of range, reasonable default settings are used instead. HSYNCLEN <len> - specifies the width of the horizontal sync pulse. Reasonable values are between 2 and 20; the default value for most monitor definitions is 14 which gives a sync pulse width of approx. 4 microseconds. Most monitors, even older ones, are satisfied with 1 microsecond, <len> value of 4. VSYNCDELAY <delay> - Modifies the position of the sync pulse in the vertical blanking period. The <delay> is an offset from the start of the vertical blanking period in scanlines, and must lie between 0 and 20; the actual maximum depends on the monitor definition and the VSYNCLEN setting. VSYNCLEN <len> - specifies the length of the vertical sync pulse. <len> is in scanlines. Reasonable values are between 2 and 10. If you specify a value that is out of range, MPATCH will use a safe default value. The MPATCH command will most likely find a place in your startup-sequence or user-startup file. It MUST be inserted after the monitor definitions have been added to the system's database; I recommend putting it somewhere at the top of your user-startup file, before any output is made to the console window, so changes to the workbench screen's monitor are effective before the workbench screen is opened. HOW TO FIND THE CORRECT SETTINGS FOR YOUR MONITOR ------------------------------------------------- Before you start patching around, you should select your "default" display mode and adjust the monitor's controls so that it fills most of the screen and is centered horizontally and vertically. If you own a monitor that has a ADD/NOR switch (might also be labeled differently on your monitor, so consult your manual), set it to ADD (or whatever it is labeled). Such switches are found on the C1960 and some older VGA/SVGA multiscans. If your monitor supports PAL or NTSC display, use one of these modes to adjust the picture position, since it is not possible to adjust the position of any video mode with MPATCH. DO NOT TOUCH any of the monitor's controls afterwards - you won't need to anyway. (Close the small trapdoor if the monitor has one!) Now, open a shell window and invoke the Overscan Preferences editor. Select the monitor you wish to patch. Click on the "Set Text Overscan" gadget. Note to which direction the display is offset. Note whether it appears vertically stretched or squeezed. Click "Cancel" (or press <ESCAPE>), and activate your shell window. Now type: "mpatch <monitor_name>", where <monitor_name> is the name of the monitor you selected in the Overscan editor. Add one or more switches following the guidelines below: * If a mode appears stretched vertically (on my C1960, the MultiScan mode used to behave this way), try the SYNCTRUE option. (Remember, this option sets both the vertical and horizontal syncs to TRUE). * If a mode appears squeezed vertically, try the VSYNCTRUE option. * If a mode is too far to the right or to the left, try the HSYNCDELAY option. * If the right border appears to be somewhat instable, try the LOLDIS switch. Press <ENTER> and go back to the Overscan editor. Click "Set Text Overscan" again. The display should now be somewhat different. If you are satisfied, note all the switches you set and add a line at the top(!) of your "S:user-startup" file. If you wish to patch your workbench screen's monitor as well, you *MUST* insert the MPATCH command before any text is printed to the console window, or the changes will not affect the workbench screen. Repeat the above steps for all monitors you wish to patch. TECHNICAL DETAILS (for those who are really interested!) -------------------------------------------------------- A) SYNC POLARITY ---------------- Some monitors, especially the C1960 and most VGA Multiscans, use the polarity of the sync signals to determine the aspect of the picture they are displaying. The term "polarity", although frequently used in this context, is not fully accurate, because the sync signals are always standard TTL level (+5V) signals. A better description would be "active-low" and "active-high". By default, the sync signals are "active-low", meaning that the sync lines are always on high (or logical "1") level and go to low (or logical "0") level only at the end of a scan line (HSYNC) or frame (VSYNC). Setting HSYNCTRUE or VSYNCTRUE reverses this behaviour. Now the lines are by default on low level and go to high level only at the end of a scan line or frame. There are 4 possible combinations of sync polarity: HSYNC NEG, VSYNC NEG - standard setting HSYNC NEG, VSYNC POS - stretches the picture vertically (all modes) HSYNC POS, VSYNC NEG - ??? (no result on my monitor) HSYNC POS, VSYNC POS - squeezes display vertically (VGA/SVGA modes only) NOTE that this behaviour applies to the C1960 monitor. Your monitor might show a completely different behaviour or no reaction at all. UPDATE: The MicroVitec 1438 shows a similar behaviour. B) SYNC DELAY AND PERIOD ------------------------ The HORIZONTAL blanking period starts at the end of each scan line and must be long enough for the beam to reach the left border before any data is being displayed. The horizontal sync signal must occur somewhere within this period. The "beam return" starts with the end of the sync pulse. Hence, the later the sync pulse occurs within the blanking interval, the more the picture will start to the left. NOTE that the sync/blanking counters are independent of display data fetch which is controlled by other register values, so it may well be possible to start scan line display before the beam has reached its leftmost position. MPATCH will not allow you to do so. The VERTICAL blanking period starts at the bottom of the frame and must be long enough for the beam to reach the top of the screen. The vertical sync signal must occur somewhere within this interval, and must be at least one scanline long in order to be recognized as a vertical sync signal by the monitor. The "beam return" starts with the end of the sync pulse. By modifying the position of the sync pulse within the vertical blanking interval it is possible to adjust the vertical picture position by a few scan lines. Specifying a positive delay will make the picture appear "higher", while specifying a negative delay will make the picture appear "lower". However, specifying a delay that is too great will result in a partially invisible display, as the beam needs some time to reach the top of the screen. LEGAL STUFF: ------------ This software is provided "as-is". No warranties are made. All use is at the user's own risk. The author assumes no liability for any incidential or consequential damage to your equipment, physical or mental health resulting from the use of this product. This software and its documentation are freely distributable but remain Copyright (c) Gregor S. M. Kuhlmann. TERMS OF DISTRIBUTION: §1 All files, especially the copyright notices, must be left intact. §2 No more than a reasonable fee to cover copying, media and mailing costs should be charged. §3 Inclusion of the software on PD Collections and magazine coverdisks is expressly encouraged. In both cases, I would like to receive a free copy of the collection or magazine (including disks). However, this is not mandatory. BUGS, COMMENTS, SUGGESTIONS: ---------------------------- MPatch has been successfully tested on an A2000 with ECS chipset, Kick/WB 3.0, 1 MB of chip memory and 9 MB of 32-Bit memory on my GVP GForce 030/25 board, and on a stock A1200 with nothing installed except a clock module, with a C1960 monitor attached to both of them. If you encounter any problems with MPatch, have some reasonable suggestions for improvements or find the program useful enough to send any money, feel free to write to the following address. You are also invited to contact me if you want to swap Japanese comic books, ANIME videotapes (Manga and others, VHS PAL only) or ANIME slide shows. This is my private MsgPort address Gregor S. M. Kuhlmann Friedhofsallee 4/5 A-2451 Hof am Leithaberge AUSTRIA EUROPE but I can also be reached at Gregor S. M. Kuhlmann c/o Digital Sound & Vision Kauergasse 10/2 A-1150 Wien AUSTRIA EUROPE (sorry no email yet, but I'm working on it ...)