Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site fortune.UUCP
Path: utzoo!watmath!clyde!floyd!harpo!ihnp4!fortune!norskog
From: norskog@fortune.UUCP (Lance Norskog)
Newsgroups: net.unix-wizards
Subject: Screen Updating
Message-ID: <2395@fortune.UUCP>
Date: Tue, 31-Jan-84 13:48:24 EST
Article-I.D.: fortune.2395
Posted: Tue Jan 31 13:48:24 1984
Date-Received: Tue, 7-Feb-84 06:00:13 EST
References: <2315@fortune.UUCP>, <1588@rlgvax.UUCP>, <2373@fortune.UUCP>
Organization: Fortune Systems, Redwood City, CA
Lines: 16

Folks, I blew it.

The Fortune screen does not update at 45kbaud, it updates at 45k chars/sec,
or 450kbaud.  This is from a test which just writes a 2000-char buffer
of ascii text.  The screen hardware is a simple character generator,
with 8 bits of attribute space for each 8 bits of character.

Our architecture allows the screen driver to reside in fast (expensive)
RAM or slow (cheaper) ROM, with a 3/2 performance hit.  We put it in ROM.
When we had it in RAM, it ran at 75k chars/sec.

Obviously, a tty driver page mode is not a luxury in this situation.

Lance C. Norskog
Fortune Systems, 101 Twin Dolphin Drive, Redwood City, CA
{cbosgd,hpda,harpo,sri-unix,amd70,decvax!ihnp4,allegra}!fortune!norskog