dhollis@shiloh.UUCP (Dan Hollis @ 7819367) (07/15/90)
Ok, I'll try to clear this up.... The problem with 50hz and 60hz, is that power supplies in the USA and Europe are different. Where the US uses 60hz cycle power, Europe uses 50hz cycle power. The ST can operate in both modes regardless of what power supply you are on (50hz/60hz) but running your ST in the mode that corresponds with your power supply makes it alot easier on your system. So, there is a little toggle in a hardware register which changes between these two modes. The address is $ff820a, you toggle bit #1 ON for 50hz, and OFF for 50hz (bit #1, not bit #0).. this sets the scan rate for the monitor as well! The vertical blank timing gets altered to match the new screen rate, so programs tied to the vertical blank will get messed up.. This is a good way to tell if a program is an import or not, because most (not all!) imports set the screen rate.. I wish they would leave the scan rate alone, and put a little sticker on the software package that says 'this program was imported' rather than fiddling with the scan rate.. =( If you know your assembly code, you *can* sometimes hack into some of the older european programs and clean the scan rate changes out, but with the newer stuff, it is usually coded/encrypted, and hacking encrypted code is no fun at all! BTW, in Blood money, there _is_ a key you can hit to change scan rates, it's F8/F9 on the main screen (not when it's booting, but when it's finished booting and asks for disk 2).. it's an undocumented 'feature'.. you want something interesting, try hitting F10 while playing the game! Hope that cleared things up!!