generating ntsc video

In article <gBjNd.3179$wK.468@newsread3.news.atl.earthlink.net>,
Jacek Mazurkiewicz  <jack@jessmaz.com> wrote:
>Can anyone give me an idea as to the bare minimum system requirements for
>generating the picture information for some NTSC video at a very low
>resolution?
>
>I'll be working with a small 8085 microcontroller for which I don't yet have
>the exact specifications (it either operates at a 1KHz or 1MHz clock
>speed), and I was wondering if I could somehow use this to generate a
>composite video signal, or if the microprocessor is underpowered for such a
>task.  I'd need some auxillary circuitry to generate the video sync
>(possibly using an LM1881).  If anyone here who's done something similar
>wouldn't mind giving a few pointers to a newcomer, please post any
>information that you think might be useful to know.

The sync generator is the LM1882, not the LM1881.  In addition it's
been renamed as the 74ACT715 (Fairchild).

For antique chips, the TI 9918/9928/9938 (used in the TI 99/4) and 
the Motorola MC6847 (used in the Radio Shack Color Computer) may 
be worth finding.  For newer chips, the Yamaha chips used in the
MSX game systems, or some of the EPSON video/LCD controllers.

The first "Home Control" computer from Steve Ciarcia's Circuit Cellar
column in Byte use one of the TI chips.  They need a couple of DRAMs 
on a seperate memory bus and communicate with a byte wide I/O port.
That project should be in his books from McGraw-Hill.

Mark Zenier  mzenier@eskimo.com  Washington State resident