program timecmos;
type str5 = string[5];
const month_name: array[0..12] of string[3] =('Err','Jan','Feb','Mar','Apr','May',
                  'Jun','Jul','Aug','Sep','Oct','Nov','Dec');
      day_of_week_name: array[0..6] of string[3] =('Mon','Tue','Wed','Thu','Fri','Sat','Sun');
      CMOS_ID_port: byte =$70;
      CMOS_DATA_port: byte = $71;

var
  hours, minutes, seconds,
  day_of_week, day, month, year,
  century_byte                              : byte;
  ch                                        : char;
  CMOS_info                                 : array[0..63] of byte;

  function valid_CMOS: boolean; begin
    port[CMOS_ID_port] := $0E;
    delay(1);
    valid_CMOS :=((port[CMOS_DATA_port])=0) end;

  function CMOS_busy: boolean;  begin
    port[CMOS_ID_port] := $A;
    delay(1);
    CMOS_busy := port[CMOS_DATA_port] and $80 >0  end;

  function read_CMOS_reg(r: byte): byte; begin
   while CMOS_busy do delay(10);
   port[CMOS_ID_port] := r;
   delay(1);
   read_CMOS_reg := port[CMOS_DATA_port] end;

  function write_CMOS_reg(r,v: byte): boolean; begin
   while CMOS_busy do delay(10);
   port[CMOS_ID_port] := r;
   delay(1);
   port[CMOS_DATA_port] := v;
   write_CMOS_reg := (read_CMOS_reg(r) = v) end;

  function num_floppies: byte; begin
    if CMOS_info[$14] and $C0=0 then num_floppies := 1
    else num_floppies := 2
    end;

  function good_flag(v,f: byte): str5;
    const ok_st: str5 = 'good';
          bad_st: str5 = 'bad';
    begin
      if CMOS_info[v] and $80 = $80 then good_flag := ok_st
      else good_flag := bad_st
    end;

procedure fill_CMOS_info;
var i: byte;
begin
  for i := 0 to 63 do CMOS_info[i] := read_CMOS_reg( i);
  seconds      := CMOS_info[0];
  minutes      := CMOS_info[2];
  hours        := CMOS_info[4];
  day_of_week  := CMOS_info[6];
  day          := CMOS_info[7];
  month        := CMOS_info[8];
  year         := CMOS_info[9];
  century_byte := CMOS_info[$32];
end;

procedure display_INFO;
var i: byte;
begin
  writeln(hours shr 4,hours mod 16,':',minutes shr 4,minutes mod 16,':'
    ,seconds shr 4,seconds mod 16);
  write('Today (',day_of_week,') is: ',day_of_week_name[day_of_week]);
  writeln(', ',day shr 4,day mod 16,'. '
    ,month_name[(10*(month shr 4))+(month mod 16) ],' ',
    century_byte shr 4, century_byte mod 16,year shr 4, year mod 16);
  writeln('  CMOS info: ');
  write('Bytes  0- 9: ');  for i :=  0 to  9 do write(CMOS_info[i]:4); writeln;
  write('Bytes 10-19: ');  for i := 10 to 19 do write(CMOS_info[i]:4); writeln;
  write('Bytes 20-29: ');  for i := 20 to 29 do write(CMOS_info[i]:4); writeln;
  write('Bytes 30-39: ');  for i := 30 to 39 do write(CMOS_info[i]:4); writeln;
  write('Bytes 40-49: ');  for i := 40 to 49 do write(CMOS_info[i]:4); writeln;
  write('Bytes 50-59: ');  for i := 50 to 59 do write(CMOS_info[i]:4); writeln;
  write('Bytes 60-63: ');  for i := 60 to 63 do write(CMOS_info[i]:4); writeln;
  writeln('Time is contained in bytes 0(sec), 2(minutes), 4(hours)');
  writeln('Alarm is contained in bytes 1(sec), 3(min), 5(hours)');
  writeln('Date is contained in bytes 7(day), 8(month), 9(year), 6(day of week)');
  writeln('Bytes 10 .. 15 contain CMOS, RTC house keeping info');
  writeln('Byte 13 MSB containes flag for good (1) battery power, bad = 0');
  writeln('Battery power is ',good_flag(13,7),'.');
  writeln('Bytes 30 and 31 contain the CMOS checksum: ', CMOS_info[30],' ', CMOS_info[31]);
  writeln('Byte 20, bits 6,7: floppy info: ',num_floppies,' drives.');
end;
begin {Time}
  if not valid_CMOS then begin writeln('CMOS invalid'); exit end;
  fill_CMOS_info;
  display_info;
  write('HAK'); read(kbd,ch);
  if write_CMOS_reg(1,0)= true then begin
    if write_CMOS_reg(3,0) = true then begin
    fill_CMOS_info;
    display_info end
 end  else writeln('Error writeing CMOS test byte');
end {Time}.