GRAPHIC

Unknown

I'm studying a FIRE.ASM sample file and I've

got these questions about asm graphic programming..

1)What are "masks"?

2)What is an IRQ mask? And how can I use it?

3)What is a NMI mask? And how can I use it?

4)What is a "palette"? How to interpret its numbers?

5)What are "ports" (accessed by IN and OUT instructions)

and why are they so important?

6)How can I reach a "port"?

Thanx for the help.

Unknown

: I'm studying a FIRE.ASM sample file and I've

: got these questions about asm graphic programming..

: 1)What are "masks"?

Masks are merely a way of blanking out part of something

which is normally enabled.

: 2)What is an IRQ mask? And how can I use it?

The IRQ mask allows you to block out hardware requests that

you don't want happening during sensitive times. It's normally

only needed for interrupt routines. You can block out IRQ's

via the PIC, Port 21h. It's a rather detailed process, so

ask it as a separate question if you REALLY need to know how to

operate it.

: 3)What is a NMI mask? And how can I use it?

One interrupt can't be masked out by the CLI command or IRQ

masking. That's the NMI, INT 2h, or Non-Maskable Interrupt.

You can mask it via a port on the motherboard, but I forget

which one. There's really no need to, as it's only called

by a hardware debugger or by the motherboard due to hardware

failure.

: 4)What is a "palette"? How to interpret its numbers?

Video modes with 256 colors or under have more different colors

than are displayable. The available colors for display out of the

total possible is the palette. Interpreting it varies by graphics

mode. Once again, this is a rather complex topic, try a separate

post and I'll try to find the time to explain it.

: 5)What are "ports" (accessed by IN and OUT instructions) and why are they so important?

Ports are the pins on the processor that interface with all the hardware.

Ports are the method of data transfer and command between floppy drives, video

hardware, etc.

: 6)How can I reach a "port"?

Ports are written to via the OUT command, and read from via the IN command.

The effects vary widely by port, so don't do anything with them unless

you have proper documentation. For example:

IN AL, 60h ;Get key from keyboard, stored in AL.

Matthew Gross

Acheron@hotmail.com

http://acheronx.resnet.tamu.edu

: Thanx for the help.

Unknown

no friggin text