VSYNC with VGA 640x350,16 color ???

johnxx

Hi there.
Could somebody tell me, how to make vsync in the 640x350, 16 colors mode ? Known at Turbo Pascal VGAmed ???

Thank's a lot!!!

Sephiroth

: Hi there.
: Could somebody tell me, how to make vsync in the 640x350, 16 colors mode ? Known at Turbo Pascal VGAmed ???
:
: Thank's a lot!!!
:
I would think you need only render the entire buffer prior to sending it to the display, and only send X number of renders where X is the refresh rate of the monitor. I haven't touched DOS since around 1994 though, so I honestly don't remember specifics.

-[italic][b][red]S[/red][purple]e[/purple][blue]p[/blue][green]h[/green][red]i[/red][purple]r[/purple][blue]o[/blue][green]t[/green][red]h[/red][/b][/italic]

Phat Nat

: : Hi there.
: : Could somebody tell me, how to make vsync in the 640x350, 16 colors mode ? Known at Turbo Pascal VGAmed ???
: :
: : Thank's a lot!!!
: :
: I would think you need only render the entire buffer prior to sending it to the display, and only send X number of renders where X is the refresh rate of the monitor. I haven't touched DOS since around 1994 though, so I honestly don't remember specifics.
:
: -[italic][b][red]S[/red][purple]e[/purple][blue]p[/blue][green]h[/green][red]i[/red][purple]r[/purple][blue]o[/blue][green]t[/green][red]h[/red][/b][/italic]
:

I think it would be the same as with all other DOS resolutions (which I still play with here and there, love DOS

Read Port 3DAh until bit 3 becomes , then immediately read it until bit 3 becomes 1. This will give you the beam at the top of the refresh.

I program in TP, but I use inline assembly for the speed. Hopefully this makes sense to you:
[code]
Mov dx,3DAh
@l1:
In al,dx
And al,08h
Jnz @l1
@l2:
In al,dx
And al,08h
Jz @l2
[/code]

I think the first loop waits until the beam hits the end, then the second is where it starts at the top. (not sure on this though)

Phat Nat

johnxx

: : : Hi there.
: : : Could somebody tell me, how to make vsync in the 640x350, 16 colors mode ? Known at Turbo Pascal VGAmed ???
: : :
: : : Thank's a lot!!!
: : :
: : I would think you need only render the entire buffer prior to sending it to the display, and only send X number of renders where X is the refresh rate of the monitor. I haven't touched DOS since around 1994 though, so I honestly don't remember specifics.
: :
: : -[italic][b][red]S[/red][purple]e[/purple][blue]p[/blue][green]h[/green][red]i[/red][purple]r[/purple][blue]o[/blue][green]t[/green][red]h[/red][/b][/italic]
: :
:
: I think it would be the same as with all other DOS resolutions (which I still play with here and there, love DOS
:
: Read Port 3DAh until bit 3 becomes , then immediately read it until bit 3 becomes 1. This will give you the beam at the top of the refresh.
:
: I program in TP, but I use inline assembly for the speed. Hopefully this makes sense to you:
: [code]
: Mov dx,3DAh
: @l1:
: In al,dx
: And al,08h
: Jnz @l1
: @l2:
: In al,dx
: And al,08h
: Jz @l2
: [/code]
:
: I think the first loop waits until the beam hits the end, then the second is where it starts at the top. (not sure on this though)
:
: Phat Nat
:
:
Thanks a lot!!! it works funnily enough, 'cause i tried it before with this routine, but it didn't want work. Thanks a lot for the hint!!!