[Toaster]

I went poking around with this and found the following:
IRQX=####
The IRQ assignment is valid but the number one uses designates "bytes" added to the FIFO buffers.
(FIFO=first in, first out)
It seems the "size" is simply a "buffer" for the IRQ to ready itself for CPU interupt service.
I dont think the value is in "megabytes" but rather "bytes" but I could be wrong. In my case, system memory did NOT drop 4 MB but 4k bytes wouldn`t be notable as a memory usage amount. There is also a "time" switch that can be used here to give particular devices more or less time on the bus. The switch you discovered adjusts the FIFO buffers and has the same effect to some degree. For devices that use a great deal of CPU time (CD-ROM and IDE devices) this could have good effect. This should work on ANY device using ANY IRQ. As to its behavior on a shared IRQ is something to discover but I suggest it simply increases the FIFO buffers for the IRQ in question and not the device per se.