tailieunhanh - The Little Black Book of Computer Viruses phần 10

Đăng ký: ah = 2 al = Số lượng của các thành phần để đọc theo dõi cùng, người đứng đầu cl = ngành số để bắt đầu đọc từ số Theo dõisố ổ đĩa để đọc es: bx = đệm để đọc ngành này vào c = thiết lập lỗi ah mã lỗi =, thiết lập như sau (đối với tất cả các 13H fctns Int) 80 H - ổ đĩa không đáp ứng 40 H - Tìm kiếm sự hoạt động không thành công | 156 The Little Black Book of Computer Viruses Interrupt 13H BIOS Disk Services Function 0 Reset Disk System Registers ah 0 Returns c set on error This function resets the disk system sending a reset command to the floppy disk controller. Function 2 Read Sectors from Disk Registers ah 2 al Number of sectors to read on same track head cl Sector number to start reading from ch Track number to read dh Head number to read dl Drive number to read es bx Buffer to read sectors into Returns c set on error ah Error code set as follows for all Int 13H fctns 80 H - Disk drive failed to respond 40 H - Seek operation failed 20 H - Bad NEC controller chip 10 H - Bad CRC on disk read 09 H - 64K DMA boundary crossed 08 H - Bad DMA chip 06 H - Diskette changed 04 H - Sector not found 03 H - Write on write protected disk 02 H - Address mark not found on disk 01 H - Bad command sent to disk i o Function 2 reads sectors from the specified disk at a given Track Head and Sector number into a buffer in RAM. A successful read returns ah 0 and no carry flag. If there is an error the carry flag is set and ah is used to return an error code. Note that no waiting time for motor startup is Appendix G BIOS and DOS Interrupt Functions 157 allowed so if this function returns an error it should be tried up to three times. Function 3 Write Sectors to disk Registers ah 3 al Number of sectors to write on same track head cl Sector number to start writing from ch Track number to write dh Head number to write dl Drive number to write es bx Buffer to write sectors from Returns c set on error ah Error code as above This function works just like the read except sectors are written to disk from the specified buffer Function 5 Format Sectors Registers ah 5 al Number of sectors to format on this track head cl Not used ch Track number to format dh Head number to format dl Drive number to format es bx Buffer for special format information Returns c set on error ah Error code as above The buffer at es bx should .

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