Contributor: JOSE CAMPIONE
program valid_drv;
uses dos;
{
Function ready_drives reports as valid only drives that are
ready to be read. Findfirst does not cause a critical error even
if a floppy is not ready and in machines with a single floppy
the prompt to insert a diskette when testing for the B: drive
(from IO.SYS) is avoided by the use of DOS services 4408ドル and
440ドルE (requires DOS 3.2 or up). -
Jose Campione (1:163/513.3) August 1994 -
}
function ready_drives: string;
var
regs : registers;
i : byte;
drs: string;
sr : searchrec;
function is_last(d:byte):boolean;
{true if d is the only or the last name assigned to that drive}
begin
regs.ax:= 440ドルE;
regs.bl:= d;
msdos(regs);
is_last:= ((regs.flags and fcarry) = 0) and ((regs.al = 0) or (regs.al = d));
end;
function is_floppy(d: byte): boolean;
{true if d is a removable medium}
begin
regs.ax:= 4408ドル;
regs.bl:= d;
msdos(regs);
is_floppy := ((regs.flags and fcarry) = 0) and (regs.ax = 0);
end;
begin
drs:= '';
for i:= 1 to 26 do begin
if (not is_floppy(i)) or is_last(i) then begin
findfirst(chr(i + 64) + ':\*.*',AnyFile,sr);
if doserror = 0 then drs:= drs + chr(i + 64);
end;
end;
ready_drives:= drs;
end;
begin
writeln('drives ready : ',ready_drives);
end.