dmb@wam.umd.edu (David M. Baggett) (03/20/91)
>European TVs work at 50 Hz. We make up for the fewer frames per second by >having more vertical resolution and properly-encoded colours. The only real reason game writers alter the scan rate is so the game play timing won't change. Games run 16.3% faster on U.S. ST's because the scan rate is 60Hz here. This means Joust, e.g., is more difficult in the U.S. than it is in the UK, something I always make clear when comparing high scores with my British competitors. :-) An example of a problem caused by the scan rate difference is the treasure room in Guantlet II. U.S. players will notice that the timer only counts down to about 4 or so, then the level ends. This is because the countdown code stupidly relies on the scan rate being only 50 frames per second (it counts a second by waiting for 50 vblanks to elapse). On U.S. machines 50 vblanks occur in 5/6ths of a second, so the timer counts down too quickly, and you only get 16.6 seconds in the treasure room instead of the normal 20. (Or is it 25?) To avoid the timing problems, some European programmers force U.S. machines into 50Hz mode. (This is accomplished by twiddling a bit in one of the video hardware registers.) Unfortunately, many early ST monitors (those made by GoldStar, I think) just can't handle the switch, and the monitor goes completely off sync. (We're talking "instant headache mode".) It's a shame too, because the GoldStars had better picture quality to my eyes. Many European games and demos are completely unuseable on my machine -- I can only assume that European folks just don't know their stuff doesn't work on a substantial portion of U.S. machines. Thank God Speedball II doesn't change the scan rate... (Hmm, this sounded a bit technical. Followups to c.s.a.s.tech...) Dave Baggett dmb%wam.umd.edu@uunet.uu.net
kentd@FtCollins.NCR.com (Kent.Dalton) (03/21/91)
>>>>> On 20 Mar 91 05:26:58 GMT, dmb@wam.umd.edu (David M. Baggett) said: >European TVs work at 50 Hz. We make up for the fewer frames per second by >having more vertical resolution and properly-encoded colours. > The only real reason game writers alter the scan rate is so the game > play timing won't change. Games run 16.3% faster on U.S. ST's because > the scan rate is 60Hz here. This means Joust, e.g., is more difficult > in the U.S. than it is in the UK, something I always make clear when > comparing high scores with my British competitors. :-) I used to have only a mono monitor and would use an old color color TV with it. The TV's controls were broken so I couldn't adjust the picture for 50Hz games and demos... Fortunately, I now also have an SC1224 that syncs to 50Hz properly. What I used to do, though, is if the game wasn't too heavily copy protected, disassemble it and look for code which changes the hardware register that controls the sync rate, then change it to put it in 60Hz. Most of the time it worked. I forget the exact address of the register but if anyone's interested I can look it up. After a while, I wrote a TSR that could toggle between 50Hz/60Hz using a hot key. This was more hit and miss, since most games/demos autoboot making it hard to install the TSR and also some completely take over the keyboard so the hot key doesn't work. If the Hz change worked, it almost never affected the functionality of the game. -- /**************************************************************************/ /* Kent Dalton * EMail: Kent.Dalton@FtCollins.NCR.COM */ /* NCR Microelectronics * CIS: 72320,3306 */ /* 2001 Danfield Ct. MS470A * */ /* Fort Collins, Colorado 80525 * (303) 223-5100 X-319 */ /**************************************************************************/ Fortune: Earn cash in your spare time -- blackmail your friends.
neil@cs.hw.ac.uk (Neil Forsyth) (03/25/91)
In article <1991Mar20.052658.9162@wam.umd.edu> dmb@wam.umd.edu (David M. Baggett) writes: ]The only real reason game writers alter the scan rate is so the game ]play timing won't change. Games run 16.3% faster on U.S. ST's because ]the scan rate is 60Hz here. This means Joust, e.g., is more difficult ]in the U.S. than it is in the UK, something I always make clear when ]comparing high scores with my British competitors. :-) Don't listen to him folks! He's just a sore loser! :-) x 10E6 ]An example of a problem caused by the scan rate difference is the ]treasure room in Guantlet II. U.S. players will notice that the timer ]only counts down to about 4 or so, then the level ends. This is ]because the countdown code stupidly relies on the scan rate being only ]50 frames per second (it counts a second by waiting for 50 vblanks to ]elapse). On U.S. machines 50 vblanks occur in 5/6ths of a second, so ]the timer counts down too quickly, and you only get 16.6 seconds in ]the treasure room instead of the normal 20. (Or is it 25?) Leaderboard conversely assumes a 60Hz frame rate. I'm not sure how this affects the game but it really screws up the demo when in 50Hz. The guy plays bad and doesn't sink the put. Proper timing should be done using Timer A in the MFP or by latching on to the system timer (Timer C) which is 200Hz everywhere (a configuration I believe that should not be changed). ]Dave Baggett ]dmb%wam.umd.edu@uunet.uu.net +----------------------------------------------------------------------------+ ! DISCLAIMER:Unless otherwise stated, the above comments are entirely my own ! ! ! ! Neil Forsyth JANET: neil@uk.ac.hw.cs ! ! Dept. of Computer Science ARPA: neil@cs.hw.ac.uk ! ! Heriot-Watt University UUCP: ..!ukc!cs.hw.ac.uk!neil ! ! Edinburgh, Scotland, UK "That was never treasure chests!" ! +----------------------------------------------------------------------------+