Yes, that's certainly an option, but was never very popular for cost reasons.
When memory got a little cheaper, it became less of an issue whether you had 11
bytes per character instead of (1 + a character-genrator). A graphic image of a
character would need about that much, at least 10 bytes, I think, if you want
full decenders. Back in the Apple and CP/M days, inexpensive microprocessors
were too slow to do that sort of thing at a reasonable rate. Later on it was
not uncommon to have different font sizes/styles/colors in the same graphic, but
that was a different era. It was never a secret that one could do this, but the
cost factor was what made character generators popular for presenting text.
Character generators (ROMs) weren't cheap either, BTW.
Dick
----- Original Message -----
From: "Pete Turnbull" <pete_at_dunnington.u-net.com>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, July 18, 2001 12:54 AM
Subject: Re: Light Pens ...
> On Jul 17, 20:22, Richard Erlacher wrote:
>
> > If the refresh memory is to support text and graphics, the pipeline must
> be
> > two-forked.
>
> Not necessarily. In a BBC Micro, for example, the 6845 is essentially
> generating a stream of pixel addresses, since what's stored in the screen
> memory is the bitmap of the character, not the character code. That's how
> you mix text and graphics on the same screen. When text is written to the
> screen, the OS looks up the bitmap(s) of the character(s) and writes the
> individual pixels to screen RAM.
>
> --
> Pete Peter Turnbull
> Network Manager
> University of York
>
>
Received on Wed Jul 18 2001 - 14:24:23 BST