Re: A83: Grbuf again

To: assembly-83@lists.ticalc.org
Subject: Re: A83: Grbuf again
From: Patrick Milheron <pmilheron@ti.com>
Date: Fri, 06 Aug 1999 07:53:33 -0500
Delivered-To: assembly-83-outgoing@towerguard.unix.edu.sollentuna.se
Delivered-To: assembly-83@lists.ticalc.org
Organization: Texas Instruments
References: <yam7887.2168.274540632@mail.telia.com>
Reply-To: assembly-83@lists.ticalc.org


Fomr what I remember when we 1st started using that
lcd driver the status check from the driver was not 
reliable. So we stopped using it and went to the
delay routine.

Later,
Pat

Linus Akesson wrote:
> 
> 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

References:

Re: A83: Grbuf again

From: Linus Akesson <lairfight@softhome.net>