Re: A86: how writing to the lcd works
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Re: A86: how writing to the lcd works
>i have a question which could be considered a hardware question, but you asm
>hopefully can answer it as it deals somewhat with asm...
>
>ok so the graphics port points to the area of mem where the image that will
>be on the screen is stored. Am i actually writing right to the lcd
>hardware. can anyone tell me how the data in the area of mem pointed to by
>the graphics port gets to the lcd.
>
>the lcd is 128 x 64 pixels = 1024 bytes ... 8192 bits or 8192 possible place
>that can be turned on or off...
>
>so inside from between somewhere and the lcd there are 128 wires
>across....how does it do the 64 down....
>
>the main thing i need to know is this a software process or a hardware
>process to organize and take and put the right data from mem to send the
>right electrons up the 128 wires to the right height.
>
>if this is a software process...does anyone know where in the rom this is.
>
>if not could someone explain how this does work.
>
>it will have asm implications for a project i'm doing...if i can figure it
>out...
None of this information is official, and none of it is confirmed, but this
is what i believe is true. Unlike the 83, there is no driver to run the
screen. Whatever is on the current bit plane is what you see on the screen.
This is all hardwired as far as i know. Using port 0, you can change where
the screen is mapped from.
equation: $100($C0+Value)
Ex:
ld a,$3C ;$3C is Value
out (0),a ;This points the offset to $FC00
There may be more extensive information on the 85, which has the same type
of screen port.
Now, when you have an 86 with one of those nifty overhead ports, i guess
that they map the screen to there as well, but it seems kind of odd, since
it definatly doesnt have 8000 little pins.
Again, no guarentees as to the validity of this info.
Chicane
chicane@reninet.com
http://zapo.calc.org
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