Path: utzoo!attcan!uunet!iscuva!jimc
From: jimc@iscuva.ISCS.COM (Jim Cathey)
Newsgroups: sci.electronics
Subject: Re: Video Circuits
Message-ID: <2471@iscuva.ISCS.COM>
Date: 27 Apr 89 23:33:52 GMT
References: <2414@lll-lcc.UUCP> <16750021@hpfcdj.HP.COM>
Organization: ISC Systems Corporation, Spokane WA
Lines: 31

In article <16750021@hpfcdj.HP.COM> myers@hpfcdj.HP.COM (Bob Myers) writes:
>The 6845 is pretty up in years ...
>The 6845 is, by current standards, a pretty "dumb" video controller...

>The 7220 is a step up; it was introduced by NEC around, oh, 1983 or so (as my
>fuzzy memory recalls), and includes some ability to manipulate the frame
>buffer data (drawing lines, circles, etc.) in addition to providing the video
>timing.  It's probably mor widely available at this time, and will give you
>considerably better functionality.

The 6845 is definitely dated, but it's widely available and quite cheap
($2 in quantity).  If all you use it for is a timing controller it's
quite fine.  We use it in our bit-mapped graphics systems, and it works
just ducky.  The 7220 is more functional on a checkoff list, but it's
also extremely slow.  Our design (using a 7 MHz 68000 to do drawing)
kicks the cookies out of a 7220.  (An 8 MHz 68000 is $6 in quantity).
To get speed out of a 7220 you can't use its built-in drawing stuff, so
you might as well just use the cheaper timing controller.

The TI 34010 _is_ a much better way to go, but it's about $70 each.  And you
still need a bunch more stuff (memory, palette, interfacing, glue...)  Not
for the faint of heart.

+----------------+
! II      CCCCCC !  Jim Cathey
! II  SSSSCC     !  ISC Systems Corp.
! II      CC     !  TAF-C8;  Spokane, WA  99220
! IISSSS  CC     !  UUCP: uunet!iscuva!jimc
! II      CCCCCC !  (509) 927-5757
+----------------+
			"With excitement like this, who is needing enemas?"