Each DMA channel has one Request and one Acknowledge line.

Similarly, DMA channel 4 is reserved for cascading 0-3 leaving seven channels active.

Some IRQ and some DMA channels are used on the motherboard and not exposed on the expansion bus.

These DMA channels performed 8-bit transfers and could only address the first megabyte of RAM.

Each DMA channel has a 16-bit address register and a 16-bit count register associated with it.

A device that uses DMA must be configured to use both lines of the assigned DMA channel.

Most notably is usage of three DMA channels to read for example from the analog-to-digital converter (ADC).

The architecture had a simple programmed I/O bus, plus a DMA channel.

Unless you at least dimly understand the innards of your computer and things like hardware interrupts and DMA channels, delegate installation to someone who does.

It should also be noted that many modern PCI bus cards also do not require free DMA channels to operate.