Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!pepper!cmcmanis From: cmcmanis%pepper@Sun.COM (Chuck McManis) Newsgroups: comp.sys.amiga Subject: Re: Cable to hook up Philips multi-sync monitor with amiga 500 Message-ID: <29417@sun.uucp> Date: Tue, 29-Sep-87 14:25:04 EDT Article-I.D.: sun.29417 Posted: Tue Sep 29 14:25:04 1987 Date-Received: Thu, 1-Oct-87 02:43:18 EDT References: <164@geocub.UUCP> Sender: news@sun.uucp Reply-To: cmcmanis@sun.UUCP (Chuck McManis) Organization: Sun Microsystems, Mountain View Lines: 46 In article <164@geocub.UUCP> anthes@geocub.UUCP (Franklin Anthes) writes: > All fine and well, the only problem was that this didn't work! >I tried disconnecting the HSYNC and VSYNC signals, and then the connection >worked! The Amiga uses the HSYNC line to determine if there is a GenLock on the video connector. If it has sufficient load (like it was being driven by a sync generator) KS 1.2 switches it to an input. Since the entire system is synced to this clock (and in your case it is not a clock at all) the system stops dead in it's tracks. In the video world you only need Composite Sync (CSYNC) -OR- Horizontal and Vertical Sync, not both since they provide exactly the same information. There is also an external clock input on the video connector that you can use to run the Amiga at different clock speeds. (Normally it runs at 28.xxx Mhz (8 * colorburst), and you can goose it to about 30 Mhz before things start not working correctly.) Note you must have a multisync monitor to do this since it will destroy the video timing. > a: what video sync signals should I have hooked up to get the most > out of my monitor? Just CSYNC, adding H & V Sync is superfluous. And it cuts down on RFI too to have just one sync line running out to your monitor. > > b: Why doesn't my amiga 500 boot when the HSYNC and VSYNC signals are > present, while my friends 1000 does fine with the same signals? > And of course what can I do about it? The Amiga 1000 is not mistaking the H and V sync lines as an external load. If you decide you can't sleep without hooking them up, try a current limiting resistor in line with the H and V sync lines. Start with 2.2K and go down until the 500 wont boot anymore. > While I'm "on the air" I'd like to send out a plea for someone to post GOFM, >because it sounds like a real godsend for anybody who is doing development on >the amiga. (like maybe even me:-) Actually a better Godsend is metascope, even if you don't like to use it. Run Metascope programname and if the system traps to one of the GURU addresses it will (like illegal instruction, or address fault) it will jump into metascope and you can look around. If it hits something like 'corrupt free list' you'll want to reboot anyway so why bother no? --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.