RTCと周期的な割り込み

Question

RTCが周期的な割り込みを生成する方法を教えてもらえますか？ここで私が試したことがあります。

mov al, 0Bh 
out 70h, al 
in al, 71h 
or al, 10000000b 
push ax 
mov al, 0Bh 
out 70h, al 
pop ax 
out 71h, al 

mov al, 0Ah 
out 70h, al 
in al, 71h 
or al, 00001111b 
push ax 
mov al, 0Ah 
out 70h, al 
pop ax 
out 71h, al 

mov al, 0Bh 
out 70h, al 
in al, 71h 
or al, 01000000b 
push ax 
mov al, 0Bh 
out 70h, al 
pop ax 
out 71h, al 

mov al, 0Bh 
out 70h, al 
in al, 71h 
and al, 01111111b 
push ax 
mov al, 0Bh 
out 70h, al 
pop ax 
out 71h, al 

私は間違っていますか？実際には、RTCをブロックするのは奇数ではないようですが、これが私が試すことができる最後のものでした。

Answer 1

私は実際のハードウェア上で動作するために使用さボーランド/ターボパスカルでいくつかの古いコードを持っているし、まだDOSBoxをして動作し、それは場合に役立ちます参照してください。

uses 
    crt, dos; 

const 
    daystr : array [0..6] of string[10] = (
    'Saturday', 'Sunday', 'Monday', 'Tuesday', 'Wednsday', 
    'Thirsday', 'Friday'); 

var 
    poldtimer : pointer; 
    irq8_enabled, 
    rtc_int_enabled : boolean; 
    int_count : integer; 
    hour, minute, second, 
    dayofweek, 
    day, month, year, century : word; 

function readcmos (reg : byte) : byte; assembler; 
asm 
    mov al, reg 
    out $70, al 
    jmp @1 
@1: 
    in al, $71 
end; 

procedure writecmos (reg, value : byte); assembler; 
asm 
    mov al, reg 
    out $70, al 
    jmp @1 
@1: 
    mov al, value 
    out $71, al 
end; 

{ New IRQ8 ISR } 
procedure irq8 (Flags, CS, IP, AX, BX, CX, DX, SI, DI, DS, ES, BP: Word); interrupt; 
begin 
    inc (int_count); 
    readcmos($c);       { W/O this, RTC doesn't work } 

    if irq8_enabled then 
    asm 
     pushf 
     call dword ptr [poldtimer]  { Call to original IRQ8 ISR } 
    end 
    else begin 
    port [$20] := $20; 
    port [$a0] := $20 
    end; 
end; 

begin 
    clrscr; 
    int_count := 0; 
    irq8_enabled := port[$a1] and 1 = 0; 
    rtc_int_enabled := readcmos ($b) and $40 = $40; 

    getintvec ($70, poldtimer);     { Save old IRQ8 ISR address } 
    setintvec ($70, @irq8);      { Set new IRQ8 ISR } 

    if not irq8_enabled then 
    port[$a1] := port[$a1] and $fe;    { Unmask IRQ8 } 

    writecmos ($a, $26); 

    if not rtc_int_enabled then 
    writecmos ($b, readcmos($b) or $40);  { Enable RTC interrupt } 

    writeln ('Testing IRQ8. Wait a second...'); 

    delay (1000);         { Little delay } 

    if not rtc_int_enabled then 
    writecmos ($b, readcmos($b) and not $40); { Disable RTC interrupt } 

    if not irq8_enabled then 
    port[$a1] := port[$a1] or 1;    { Mask IRQ8 } 

    setintvec ($70, poldtimer);     { Restore old IRQ8 ISR } 

    writeln ('Counts per second: ', int_count); 

    writeln ('Current time and date:'); 
    repeat 
    gotoxy (1, wherey); 
    while (readcmos($a) and $80 = $80) do; 
    second := readcmos(0); 
    minute := readcmos(2); 
    hour := readcmos(4); 
    dayofweek := readcmos (6); 
    day := readcmos (7); 
    month := readcmos (8); 
    year := readcmos (9); 
    century := readcmos ($32); 
    write (hour shr 4, hour and 15, ':', minute shr 4, minute and 15, ':', 
      second shr 4, second and 15, ' '); 
    write (day shr 4, day and 15, '/', month shr 4, month and 15, '/', 
      century shr 4, century and 15, year shr 4, year and 15, 
      ' [', daystr[dayofweek], ']'); 
    until keypressed; 
    while keypressed do readkey; 
    writeln 
end. 

それは（DOSBoxをして）出力します。

Testing IRQ8. Wait a second... 
Counts per second: 1048 
Current time and date: 
03:13:19 30/03/2012 [Friday]