🚀 go-pugleaf

I have the following it of code which was given to me. Aside from the "few"
errors, the person claims that this will cause a message:

ON BOARD PARITY ERROR
ADDR (HEX) = (xxxx:xxxx)
SYSTEM HALTED.

This apparently appears when the following is run:

mov al,74
out 43,al
mov al,ff
out 41,al
mov al,ff
out 41,al
ret

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I can not check this since I am running OS/2 and traps the error before it
appears on the screen. The person claims that he interfers with the DMA
refresh rate and this is the reason a parity error appears.

Could someone check if this is the case and if so, why the error appears. From
my understanding, a parity error can only be caused by DRAM and I/O parity
errors. Furthermore, on the PC AT, 2BH and 29H are the post addresses for the
Interrupt controller (8259A). THe Programmer's PC Sourcebook mentiones that
ports 20 and 21 are only used. There seems to be something very strange going
on with this program. Thanks...

Mark K.
E-Mail: kovarski@zooid.guild.org