segments

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GhostXoPCorp

Joined: 13 Dec 2008
Posts: 199
Location: 01F0:0100

GhostXoPCorp 04 Jun 2009, 21:31

my os is in real mode, everything is only up to ffffh thats it (0xffff)
i see how the whole 0000:0000 thing works (not all though)
i have yet to find out wha happens if

a file is loaded at 2000:0300
now what happens when i load something at 3000:0300 will it over write :0300
in the last load or will the 3000: be erased, what happens?

_________________
Oh that divide overflow. Just jumps out of the bushes every time to scare the day lights out of me.

04 Jun 2009, 21:31

bitRAKE

Joined: 21 Jul 2003
Posts: 4042
Location: vpcmpistri

bitRAKE 05 Jun 2009, 02:45

SEG:OFF can be converted to a linear address with SEG * 16 + OFF. So, 2000:0300 would be a linear address of $20300. 3000:0300 would be a linear address of $30300. Therefor, if the file loaded at 2000:0300 was over $10000 bytes then the following load at address 3000:0300 would over write a portion of the file.

05 Jun 2009, 02:45

GhostXoPCorp

Joined: 13 Dec 2008
Posts: 199
Location: 01F0:0100

GhostXoPCorp 05 Jun 2009, 08:14

thanks for the info

_________________
Oh that divide overflow. Just jumps out of the bushes every time to scare the day lights out of me.

05 Jun 2009, 08:14

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