Contributor: BRAIN PAPE
{===========================================================================
Date: 10-03-93 (00:14)
From: BRIAN PAPE
Subj: disk ready
---------------------------------------------------------------------------
Does anyone know if there is any better (and FASTER!) way to tell if a
disk drive is ready? I wrote a function yesterday to do that by calling
the BIOS Read Track interrupt. The only problem is that it has to
actually read from the disk, and it is rather slow, especially on slower
computers.
Here is my code: }
{ NOTE :
Added a BOOLEAN function and added Reset DRIVE GDAVIS 10/15/93}
USES CRT;
VAR
Buf : ARRAY[0..512] OF BYTE; { Buffer MUST be outside }
function diskstatus(drive:byte):byte; assembler; { drive is A=0, B=1 etc}
asm
cmp drive,26
jb @driveok
mov drive,0 { if drive isn't between 0 and 25, make it 0 (for A:) }
@driveok:
mov ax, seg buf
mov es, ax
mov bx, offset buf
mov ah, 02 { read disk sectors }
mov al, 1 { number of sectors to transfer }
mov ch, 1 { track number }
mov cl, 1 { sector number }
mov dh, 1 { head number }
mov dl, drive { drive number (0=A, 3=C, or 80h=C, 81h=D) }
int 13h
mov bl,0 { assume drive is ready }
jnc @done { carry set if unsuccessfull (i.e. disk is not ready) }
mov bl,ah
jmp @done
{ take out the above two lines to make this just check
for disk ready/not ready }
and ah,80ドル
jz @done { error was something other than disk not ready }
mov bl,false{ disk wasn't ready. store result }
@done:
mov ax,0000ドル { reset drive }
INT 13H
xor ax,ax { shut off disk drive quickly }
mov es,ax
mov ax,440h
mov di,ax
mov byte ptr es:[di],01h
mov al,bl { retrieve result }
end; { diskstatus }
function diskready(drive:CHAR):BOOLEAN; assembler;
asm
cmp drive,'a'
jb @isupcase { make it UPPER case }
sub drive,20H
@isupcase:
cmp drive,'Z'
jb @driveok
mov drive,'A' { if drive isn't between 'A' and 'Z', make it A) }
@driveok:
mov ax, seg buf
mov es, ax
mov bx, offset buf
mov ah, 02 { read disk sectors }
mov al, 1 { number of sectors to transfer }
mov ch, 1 { track number }
mov cl, 1 { sector number }
mov dh, 1 { head number }
mov dl, drive
sub dl, 'A' { subtract ORD of 'A' }
{mov dl, drive { drive number (0=A, 3=C, or 80h=C, 81h=D) }
int 13h
mov bl,true { assume drive is ready }
and ah,80ドル
jz @done { error was something other than disk not ready }
mov bl,false{ disk wasn't ready. store result }
@done:
mov ax,0000ドル { reset drive }
INT 13H
xor ax,ax { shut off disk drive quickly }
mov es,ax
mov ax,440h
mov di,ax
mov byte ptr es:[di],01h
mov al,bl { retrieve result }
end; { diskready }
BEGIN
ClrScr;
WriteLn(DiskStatus(0));
WriteLn(DiskReady('a')); { case ain't significant }
readkey;
END.