[Coco] An interesting Question to the Software gurus

[jdaggett at gate.net]

All 

I have been pondering something about the GMIE chip the past few 
days and have come to an interesting point. 

This is my understanding of how the Interrupts from the GIME chip 
work.   

Bits #5 and #4 of $FF90 act as Global enable/disable. A one to 
these bits allow the GIME chip to output an IRQ/FIRQ to the CPU. It 
appears that $FF92 and $FF93 act as local IRQ enable/disable and 
as status Flag. It seems that if you write $00 to $FF92 and $FF93 
that will also do the same thing as writting a "0" to bits 5 and 4  of 
$FF90. Here is my question and ponderance! If IRQ/FIRQ are 
disabled by writing $00 to $FF92 and $FF93,  are the flags still set 
when a peripheral device generates an IRQ/FIRQ? If so then this 
should allow the peripheral device to be used in polled mode intead 
of IRQ mode. Does OS9 or RSDOS  work in this mode?


james