Open source, stand alone, ASCII terminal project

Mr Ian Primus ian_primus at yahoo.com
Mon Dec 1 18:52:41 CST 2008


--- On Mon, 12/1/08, Chuck Guzis <cclist at sydex.com> wrote:

> > I think the best you could get is 40x24 or even less
> without the fonts
> > becoming a big mushy blur.
> 
> Going through a modulator or direct video input?  With
> direct video, 
> an NTSC TV can probably do 80x24.  Of course, you don't
> get ginormous 
> dots-per-character (7x7 is pretty typical), but you can do
> it.  Why 
> should this be any different from the NTSC-scan-frequency
> IBM CGA 
> monitor?

The primary difference here is the color decoding. You can get very legible, crisp, clean text on a CGA monitor, or a Commodore Amiga RGB monitor - both of which run at the standard NTSC rates. But in both cases, the set doesn't have to decode the color signals - they're separate. Most off-the-shelf TV sets and video monitors, even those with direct video input, will have a tough time giving clear 80 column text. Some of the better designed monitors, those meant specifically for computer use, such as the Apple color composite monitor - can produce good text. Others, such as a cheap color TV, won't work so well. A color picture tube is somewhat worse at providing a crisp monochrome text screen, due to it's phosphor design and the resolution limits thereof, but this is not the force that causes the fuzzy text. It's the color demodulation.

Monochrome monitors will almost universally (except for the very low quality) give legible 80 column text. I've even gotten legible 80x25 text out of a $20 portable black and white 5" TV, although the contrast/brightness controls had to be just so.
 
> My first video monitor was a Zenith B&W portable (tube)
> hot-chassis 
> TV that I won in a raffle and fed directly into the video
> amp from my 
> SWTP TVT II modified to give 64x16.  It looked fine, even
> if it was 
> foolish on my part.

Hehe. Been there, done that, have the blown fuses to show for it. For a while, I was using a 19" tube type black and white TV that I'd modified as a monitor for an Apple IIe. It worked great, and 80 columns was very usable. The set was hot chassis, and since I didn't have an isolation transformer, I'd modified the power cord of the TV such that it could only be plugged in one way, so the chassis was on the "neutral" side. All was well until I moved the setup to a friends house to play some games and copy disks. In the process, I'd inadvertantly unplugged the power cord from the back of the TV (hehe, "This cabinet back is equipped with a safety interlock, do not defeat it's purpose. Remove cover completely for service"). Plug in, switch on, >piff!< tripped the breaker. After reversing (and marking) the cable, and resetting the breaker, everything worked fine.

-Ian




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