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From: elg@usl.UUCP (Eric Lee Green)
Newsgroups: net.micro.cbm
Subject: Re: 80 columns on the C-64
Message-ID: <867@usl.UUCP>
Date: Tue, 19-Aug-86 20:03:23 EDT
Article-I.D.: usl.867
Posted: Tue Aug 19 20:03:23 1986
Date-Received: Thu, 21-Aug-86 21:09:29 EDT
References: <306@tekgen.UUCP> <648@ulowell.UUCP>
Reply-To: elg@usl.UUCP (Eric Lee Green)
Organization: USL, Lafayette, LA
Lines: 38

In article <648@ulowell.UUCP> dfoley@ulowell.UUCP (the Aberration) writes:
>My problem: I am ambitiously trying to write a terminal program for the
>C-64, and have decided that it will be near useless without an 80-column
>display. I am aware that there are several boards out to do this, but am
>interested in a software-only solution. I would prefer to write my own, but
>can't decide all that would be involved. Has anyone got any theories on
>this? Please post responses, as my mailbox is kludgey.

Well, first thing you need to understand is how the C-64's hi-res
screen is laid out: as 8 bit by 8 byte squares (tat's right, the size
of a character!). To do pseudo-80-column, you just need a 4-bit-wide
font, and use the old and/or masking method to stuff it into the left
side or right side of that 8 by 8 square (depending on whether your 80
column "cursor" is on an odd or even number). The easy way to do this
is to have a double-defined font... that is, each character position
in the font is two 4-bit characters, one for each side of the 8-bit
character. 

For more information, I posted the sources to JAFT (an 80 column
TVI910 emulator) to the net a couple of months ago. I'll mail a copy
to anybody who mails me $2.50 (I get disks real cheep because the
computer club I belong to buys them bulk-rate, but the mailer and
postage add up). I also have a PROMAL implementation that I wrote just
playing with the concept of software-emulated 80 columns... however, I
don't know what disk it's on (I have two disk boxes full of old
programs I've written that I need to sort through, clean up, and
catalog... but I so hate deleting things, I'm such a pack-rat...).
If I find the Promal implementation, I'll post it to the net.

-- 

      Eric Green {akgua,ut-sally}!usl!elg
        (Snail Mail P.O. Box 92191, Lafayette, LA 70509)
          Bayou Telecommunications' ML guru, USL student

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