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Message from discussion semi-ot: motorola 6847
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Tarkin  
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 More options Jun 3 2012, 10:30 am
Newsgroups: comp.os.cpm
From: Tarkin <tarkin...@gmail.com>
Date: Sun, 3 Jun 2012 07:30:18 -0700 (PDT)
Local: Sun, Jun 3 2012 10:30 am
Subject: Re: semi-ot: motorola 6847
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On Jun 3, 4:21 am, Torfinn Ingolfsen <ti...@home.no> wrote:

> On 06/03/2012 09:23, Tarkin wrote:

> > Context:
> >    I know I've read more than once where some people find using a pc
> > as a serial terminal to a cp/m SBC or system a "waste".

> >    Noting that older crt-based serial terminals are dying off, I've
> > been
> > researching ways to drive NTSC (or PAL...) TVs and compatible LCDs
> > (don't laugh, small ones for camera interface are around 20USD...)
> > from a micro controller...

> Great! Kind of the way PockeTerm works:http://www.brielcomputers.com/wordpress/?cat=25
> except that it uses "normal" LCD monitors with VGA input.

> >    The best of the micro controller designs I've seen use two PICs- one
> > to process and drive data to the second, which produces line signals.

> Then you haven't look hard enough. There are a lot more than PIC
> microcontrollers out there.

yes....

Propellers, to my mind, are actually more than one microcontroller.
The arduino is an entire board.

> > A) Is the 6845 even feasible as a video signal generator? It seems
> > more like a glorified DRAM refresh controller...
> > B) Can the 6847 be used standalone, without an r/f modulator?
> > I.E., can one simply tap the Y output for monochrome video, and/or
> > Y + ϕA + ϕB for color (S-Video)?

> You do not need a specialized chip to generate a video signal.

Correct. But if I was.....

> Any fast enough microcontroller with enough pins can do it, using
> resistors as a D/A converter.

Yes. The PIC Pong is one of the oldest.

> For both composite and VGA output. Some example quickly found with Google.

> Arduino:http://arduino.cc/playground/Main/TVouthttp://little-scale.blogspot.n...

> Propeller:http://forums.parallax.com/showthread.php?140426-VGA-using-8-bits-RRR...

> HTH
> --
> Torfinn Ingolfsen,
> Norway

The Propeller may be worth a look, although it would make more sense
just to build the rest of a CP/M emulator with the remaining cores...

Thanks!

TTFN,
  Tarkin


 
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