[A83] Re: lcd mem as ram
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[A83] Re: lcd mem as ram
On Fri, 4 Jan 2002, Olle Hedman wrote:
> when you write to the dataport, you can set the internal pointer to the lcd
> controller ram to either increase in x or y automaticly.
> default in the tios is incrementing in x, so you have to write a command to
> the lcd to change line.
> The fast screen update routines, like the one that comes with ION, set it
> to y-increment instead, then you write a column (or 8 columns, since you
> write bytes) before you have to change column, so you only have to do 12
> writes to the lcd command port to change column, instead of 64 writes to
> change line.
> this, and that they have less delay between writes instead of the tios call
> to a delayroutine which is quite oversized, makes them a lot faster.
> so x-incrementing and y-incrementing is only two different modes of the lcd
> controller that you can switch between by writing a certain command to the
> lcd controller.
> did this answer your question?
Wasn't x-incrementing vertical and y-incrementing horizontal? The TIOS
expects the lcd driver in x-increment mode, but the standard TIOS gbufcpy
routine switches to y-increment as that makes reading the contents of the
screen buffer easier. Joe's FastCopy routine uses x-incrementing and uses
the necessary additions (to get the proper screen buffer data) as delays
between two writes.
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