* Yet another programming file, this time relating to the BIOS Trap calls, again it should prove very useful if you don't already have this information, or would prefer to have it as an ASCII file. ----------------------------------------------------------------------- BIOS Calls Trap #13 ----------------------------------------------------------------------- Conventions: d0 is data register 0 d0.w means the lowest 16 bits in d0 - the high bits are undefined d0.l means a long word value is returned - all bits are defined d0.hw means the highest 16 bits of d0 d0.lw means the lowest 16 bits of d0 undefined means the bits can (and frequently do) have ANY value d0.hw, d0.lw are always used TOGETHER i.e all bits are defined move = move.w for error codes see: System Exceptions, GEMDOS,BIOS error codes (0) getmpb Get memory pointer block move.l #buffer,-(sp) buffer address move #0,-(sp) function number trap #13 addq #6,sp stack correction buffer ds.b 12 Result: .l pointer to memory free list memory descriptor [md] .l pointer to memory allocated list md .l pointer to roving md (1) bconstat Character device input status .wait move #2,-(sp) device move #1,-(sp) trap #13 addq #4,sp beq.s .wait results d0.w 0 no characters are available d0.w -1 character/s available devices: 0 prt printer parallel port 1 aux rs-232 2 con console, the screen 3 midi port 4 kbd keyboard ops: 0 prt 1 aux 2 con 3 midi 4 kbd bconstat no yes yes yes no bconin yes yes yes yes no bconout yes yes yes yes yes bcostat yes yes yes yes yes (2) bconin Read character from device move #dev,-(sp) device as above move #2,-(sp) trap #13 addq #4,sp results: does not return until a character is input d0.l $0000cccc c=character if dev = 2 (console) then d0.hw=scancode d0.lw=character (3) bconout Write character to device move #char,-(sp) character to output move #dev,-(sp) output device move #3,-(sp) trap #13 addq #6,-(sp) results: dev is device as listed above does not return until character written (4) rwabs Read/write logical sectors on a device move #drive,-(sp) drive move #logsect,-(sp) logical sector to start at move #numsect,-(sp) number of sectors read/write pea buffer address of buffer move #flag,-(sp) operation move #4,-(sp) trap #13 lea 14(sp),sp buffer ds.b 512*numsect results: bios error code flag is 0=read 1=write 2=read do not affect media change 3=write " " " " " buffer is read/write buffer, word aligned. numsect is number of sectors to tranfer logsect is where to start transfer drive is 0 drive A 1 drive B 2+ Hard discs, networks etc (5) setexc Set exception numbers move.l #vec_addr,-(sp) move.l #vec_num,-(sp) move #5,-(sp) trap #13 addq #8,sp vec_addr ~~~~ rte Results: d0.l odd interrupt vector, restore before exiting vec_num is the number of the vector to get or set vec_addr is the address of the new vector to be installed or is -1.l in which case only a read of the vector is done. (6) tickcal Timer calibration move #6,-(sp) trap #13 addq #2,sp Results: d0.? system timer calibration value, to the nearest milli second. (7) getbpb Get bios parameter block move #dev,-(sp) move #7,-(sp) trap #13 addq #4,sp Results: d0.l pointer to the BIOS parameter block for specifed drive or returns 0.l if bpb cannot be determined. the bpb: word sector size in bytes (512) word cluster size in sectors (2) word cluster size in bytes (1024) word directory lenght in sectors (7) word FAT size in sectors (5) word sector number of FAT 2 word sector number of the first data cluster word number of data clusters on the disk word flags bit 0 0=12 bit fat 1=16 bit fat (8) bconstat Return output device status move #dev,-(sp) move #8,-(sp) trap #13 addq #4,sp Results: d0.w 0 device no ready -1 device ready dev is as above (9) mediach Inequire media change move #dev,-(sp) move #9,-(sp) trap #13 addq #4,sp Results d0.w 0 no media change 1 possiable mc 2 media change GEMDOS will respond to a return value of 1 with a read operation. If the BIOS detects an absolute media change, it will return a "media change" error at that time (10) drvmap Return drive map move #10,-(sp) trap #13 addq #2,sp Results: d0.l A bitmap of all drives 1 = connected 0 = not connected (11) kbshift Set/return shift key status move #mode,-(sp) move #11,-(sp) trap #13 addq #4,sp Results: d0.w bit use 0 right shift key 1 left shift key 2 control 3 alt key 4 caps-locks 5 right mouse button (clr/home) 6 left mouse button (insert) 7 reserved