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©annax1 PC-technology Keyboard Graphics Interface cards.

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Presentation on theme: "©annax1 PC-technology Keyboard Graphics Interface cards."— Presentation transcript:

1 ©annax1 PC-technology Keyboard Graphics Interface cards

2 ©annax2 Keyboard Scan matrix fig p SDU - serial data unitfig. p Keyboard interrupt - IRQ1 Scan code ASCII code

3 ©annax3 Keyboard Accessing the keyboard –BIOS memory area called keyboard buffer addresses from 40:17 to 40:1d, 40:80, 40:82, 40:96 to 40:97 - pointers and status bytes addresses 40:1e to 40:3d (32 bytes) - data area fig 34.4 p –Access via interrupts BIOS INT 16H DOS INT 21H –Access directly via ports port 60H, port 64H

4 ©annax4 Graphics Fig p.1045 –Character ROM –Character generator –Attributefig –Signal generator –Video RAMfig –Palettesfig

5 ©annax5 Graphics BIOS data area 40:10video adapter BIOS data area 40:49 to 66 cursor positions, active page, control registers etc. Adress area in RAM: –Text modeB800:0000 –Graphics modeA000:0000 –low byte = character, high byte = attribute

6 ©annax6 Peripherals, Interface cards IRQ(page 394) I/O-address area DMA-channel

7 7 Peripherals, Interface cards

8 ©annax8 Peripherals, Interface cards Example: I/O-address area for COM ports


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