Re: accessing device memory

spamtrap@xxxxxxxxxx schrieb: 
Hiya,

Prehaps this a basic question and not suited here, however I hope you
can offer me some guidance.

I have recently read on www.hackaday.com "Hiding behind antiquity",
whislt there is currently no slides or notes from this presentation I
have wondered for a long time how to access the memory of devices, such
as the NIC and Graphics Cards.

I have just ordered the " IA-32 Intel® Architecture Software
Developer's Manual, Volume 1: Basic Architecture" with the hope that
this will provide me some information as to the address of these
devices?

with ASM (or C, but thats not your department...) how would I go about
reading x number of bytes from a memory location?


Read one byte(ASCII) from the text-ram(upper left corner).
debug
-a
xxxx:0100 mov ax,B800
xxxx:0103 mov ds,ax
xxxx:0105 mov di, 0
xxxx:0108 mov al,[di]
xxxx:010A
G=CS:0100 010A

AX=xxXX BX=0000
     ^^
Now the byte(XX) is stored in the AL-Register the lower part
of the AX-Register.

....or...

-d b800:0

-q = To quit debug

Dirk

.

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