Re: A83: Grbuf again

To: assembly-83@lists.ticalc.org
Subject: Re: A83: Grbuf again
From: Linus Akesson <lairfight@softhome.net>
Date: Fri, 06 Aug 1999 01:05:43 +0200
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-83@lists.ticalc.org
In-Reply-To: <37A9FA0C.B3E921B1@calc.org>
Reply-To: assembly-83@lists.ticalc.org


In accordance with the prophecy, Scott Dial uttered:

> AHH... I am tired of people wasting 5 bytes! It is in the rom...
> lcd_busy is in the include file!

Yes, it's in the rom and the rom version is compatible with new, faster
versions of the ti-83 (I assume), _BUT_ TI documents that the routine that
causes the needed delay is:

push af
inc hl
dec hl
pop af
ret

together with a call to that routine. Calling the rom routine wastes several
clock cycles, which is why I used my own routine in Ride - The Demo.

However, these lcdbusy routines are not very lcd-driver friendly. Reading
port 10h and checking bit 7 would be the correct procedure, but would of
course be quite slow.

Linus

- --- Linus Akesson ------------------------ http://linusworld.cjb.net --- -


       Those are my principles. If you don't like them I have others.
                                                      -- Groucho Marx

Follow-Ups:

Re: A83: Grbuf again

From: Patrick Milheron <pmilheron@ti.com>

References:

Re: A83: Grbuf again

From: Scott Dial <wrath@calc.org>