On Jul 9, 2011, at 11:43 AM, Doug McNutt wrote: > > Audio goes to a speaker and a phone jack and was never mixed with the video > in a composite output. Some third party may have made an NTSC, National > Television Standards Committee, conversion to allow for a second monitor but > I never saw it. Apple's earlier Apple II line did put out NTSC video and you > could run a TV monitor from that but even there I don't think the audio was > ever mixed with the video.
Composite video does NOT carry audio. Composite video and audio can both be modulated onto an RF carrier which is how analog TV worked. > > It was the SE, system extendable, series that first had an internal plug-in > capability. That made it possible to drive a lot of monitors probably > including third party color NTSC composite. Radius was a major supplier of > cards for that. The SE doesn't support Color Quickdraw so the number of color video boards is very limited. AFAIK there was one board that let you do the 8 colors of original QuickDraw. But this may have been a SCSI interface, it's been quite a while since I saw it. > > NTSC is a 14.5 or so kHz horizontal scan rate with a 30 Hz vertical refresh > rate. Video bandwidth is about 4 MHz. The horizontal lines are interlaced > with all odd lines delivered on one vertical pass while the even lines are > delivered on the next. That tends to eliminate perceived fluctuations in TV > sets. Color NTSC has other things added. Interleaving was a method to double the number of scan lines of the original NTSC format while maintaining both forward and backward compatibility Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/
