Q on VGA font table location

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IdioticMoron

Joined: 17 Oct 2018
Posts: 4

IdioticMoron 07 Jan 2019, 23:37

In my quest to find a way to print text in mode13 using bitmap fonts, I found a code snippet that works. However, the money line is below:

lgs di,[fs:43h*4]

I get some of this. Load far pointer to the BIOS 8*16 font located at 43h. So what does the *4 do??

_________________
gee that's a large beetle
i wonder if it's poisonous?

07 Jan 2019, 23:37

DimonSoft

Joined: 03 Mar 2010
Posts: 1197
Location: Belarus

DimonSoft 08 Jan 2019, 04:04

If FS is zero by then, 43h*4 stays for the offset of vector 43h within IVT: TechHelp: INT 43H: EGA/VGA Graphics Character Font Pointer

08 Jan 2019, 04:04

zhak

Joined: 12 Apr 2005
Posts: 501
Location: Belarus

zhak 08 Jan 2019, 14:05

Each entry in interrupt table is 4 bytes. To get offset to entry number 43h you obviously should multiply it by entry size

08 Jan 2019, 14:05

IdioticMoron

Joined: 17 Oct 2018
Posts: 4

IdioticMoron 08 Jan 2019, 14:16

Thanks for the responses! Cool

_________________
gee that's a large beetle
i wonder if it's poisonous?

08 Jan 2019, 14:16

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