lucifer@world.std.com (Kevin S Green) (05/11/91)
I have been researching RGB monitor options for the Apple //gs and I need to
get answers to some slightly technical questions. When selecting a monitor,
1) is the "dot pitch"/"pixel density"/"mask pitch" (measured in millimeters)
relevant? If so, what dot pitch (or range of pitches) is usable with the //gs.
2) is the horizontal & vertical "scanning frequency" (measured in KHz)
relevant? If so, what range of frequencies is acceptable?
3) what relevance does "video bandwidth" (measured in MHz) have? (Some
examples: Magnovox 1CM135 has bandwith of 6.5 MHz, Zenith ZCM-1492 has
bandwith of 28MHz, Goldstar Model 1610 VGA has bandwith of 45Mhz, NEC
MultiSync 2A has bandwith of 38Mhz)
4) what kind of RGB connector does the //gs use and what kind of connectors
on the monitor are not convertable (ie BNC, DB9-15p, DB9P, DB15P, DB25P,
DA15, etc).
5) is "input signal" relevant? (Example: Zenith ZCM-1492 is 0-.714 volts)
6) is "interlaced" vs. "non-interlaced" resolution relevant?
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Kevin S. Green / lucifer@world.std.com / {xylogics;uunet}!world!lucifertoddpw@nntp-server.caltech.edu (Todd P. Whitesel) (05/11/91)
lucifer@world.std.com (Kevin S Green) writes: >1) is the "dot pitch"/"pixel density"/"mask pitch" (measured in millimeters) >relevant? If so, what dot pitch (or range of pitches) is usable with the //gs. These are just measures of how nice the picture will look. With the //gs the better the monitor resolution is, the better your 640 mode dithered colors will look. Most monitors have little aliasing patterns when displaying 640 mode colors because of the 2-pixel dithering that is used. >2) is the horizontal & vertical "scanning frequency" (measured in KHz) >relevant? If so, what range of frequencies is acceptable? The GS outputs 15.7 Khz horizontal, 60 hz vertical -- effectively the same as VCR/TV signals. (See #6 below.) >3) what relevance does "video bandwidth" (measured in MHz) have? (Some >examples: Magnovox 1CM135 has bandwith of 6.5 MHz, Zenith ZCM-1492 has >bandwith of 28MHz, Goldstar Model 1610 VGA has bandwith of 45Mhz, NEC >MultiSync 2A has bandwith of 38Mhz) This is basically the densest 'checkerboard' pattern you can display with the monitor. The bandwith of 640 mode video is either 16 or 8 mhz depending on whether they mean the maximum dot rate or the actual electrical bandwidth (which is half of the dot frequency since the worst case video signal is _alternating_ white and black dots). Anything over that will have no problems displaying crisp 640 mode text. >4) what kind of RGB connector does the //gs use and what kind of connectors >on the monitor are not convertable (ie BNC, DB9-15p, DB9P, DB15P, DB25P, >DA15, etc). The GS has a DB-15 which is similar but not quite identical to the connector used by color Macs. Only composite sync is available, both externally and internally (on all three RGB lines, BTW). Some monitors that take seperate vertical and horizontal sync will in fact accept an external sync at both inputs and work -- the Commode Door 1084 appears to work this way, although you might need to put a bit of resistance between the two sync inputs so they don't interfere with each other (really, it's highly dependent on how the monitor sync circuits were designed, you usually have to just experiment). >5) is "input signal" relevant? (Example: Zenith ZCM-1492 is 0-.714 volts) hm. It _should_ be 1.0 volts peak-to-peak. That's the RS-170a standard. >6) is "interlaced" vs. "non-interlaced" resolution relevant? Not really. Interlaced is simply twice as many lines but with flicker. Todd Whitesel toddpw @ tybalt.caltech.edu
gwyn@smoke.brl.mil (Doug Gwyn) (05/12/91)
In article <1991May11.110738.8916@nntp-server.caltech.edu> toddpw@nntp-server.caltech.edu (Todd P. Whitesel) writes: >Interlaced is simply twice as many lines but with flicker. That's misleading. Your home color TV set interlaces at the same rate as a IIGS monitor (using, for example, Apple's Video Overlay Card in 400-line mode), and it doesn't flicker. It depends on the phosphor persistence. Actually, the only time I see appreciable flicker on my Apple RGB monitor in interlaced operation is when there is a single- pixel horizontal line. Most images look fine.
daveh@ccwf.cc.utexas.edu (Dave Huang) (05/13/91)
In article <16131@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes: >In article <1991May11.110738.8916@nntp-server.caltech.edu> toddpw@nntp-server.caltech.edu (Todd P. Whitesel) writes: >persistence. Actually, the only time I see appreciable flicker on my >Apple RGB monitor in interlaced operation is when there is a single- >pixel horizontal line. Most images look fine. Yes, and you're really not supposed to do that anyway... I forgot where I heard this, but one is taught never to make a single pixel horizontal line when doing video overlay or computer graphics to be viewed on TV... -- David Huang | Internet: daveh@ccwf.cc.utexas.edu | "Help! My ganglion is UUCP: ...!ut-emx!ccwf.cc.utexas.edu!daveh | stuck in some chewing gum!" America Online: DrWho29 |