Martin S�fke wrote:
(... but I missed his first mail. I assume the bug is only in the time display, not in
time going
ahead/back or something similar).
>write('CMOS time: '); {Hack time out of CMOS}
>port[$70]:=(port[$80] and $80) or $04; {Display it in BCD}
Why do you read port $80 instead of port $70? (BTW this is harmless)
Ok, so you set the address latch to read register 4 (hours).
>write(hexbyte(port[$71]));
Read the value in BCD format (default) and display it in hex.
The value is wrong because of a bug in dosemu (missing BCD conversion
for hours). Corrected, thank you.
>write(hexbyte(port[$71]),' binary: ');{Display it in Binary}
I hope you didn't think "now I set the clock to binary mode", because
it is still in BCD (you need to write status register B to change mode).
You just display BCD values in decimal, which makes no sense.
BTW the MC146818 datasheets and two of my books say that bit 2=0 means
BCD and 1 means binary. However, a third book says the contrary.
There is a wrong comment in dosemu because of this, but the code
is right.
>port[$70]:=(port[$80] and $80) or $0B; {Display CMOS settings for clock}
>if (port[$71] and $04)=$04 then write('binary') else write('BCD');
>port[$70]:=(port[$80] and $80) or $0B;
>if (port[$71] and $02)=$02 then write(' 24h ') else write(' am/pm ');
>port[$70]:=(port[$80] and $80) or $0B;
>if (port[$71] and $01)=$01 then writeln(' DLS') else writeln;
Second "bug" in dosemu: the DLS was disabled because it is obsolete and
unused. If you write 1 in bit 0 of status reg B, you still read 0. Give
me a good reason to set this bit...
Patch against 0.99.12 follows. (Hans: I will not resend this one)
begin 644 cmos.dff.gz
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MAC"$8!P%HVAX!L%D,FD[CO,O2?=`$_#]*#R-PG$-='$!7C`8N4$(CGT/X>*B
M#2TX@604LY(D.0.2$UD`+W6S,=QN5!M*-#O8&<3J9T4D@T?RP$!4NNW9]3#&
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MG^Q'PF"``H)C7B-;)FQQ,$5=F8;OF+\DNT<'_C+2*2VK%,U2P(DNIFT/;+@N
M-K8V5:GX?<DHI!F1]2J>,2VUTK;N*_-MJN!9L$>NTPPZ!K^&/[#W]2PZ7IE_
MNXE,$EN_&X'6]JR'>)ES]/*Z*E/-L:5,<W=-,UEG9O#(\QP)L?0')%Q#"&)=
MPV!;-M9#`G!EY\9&B@UV'HZS3:7-2H':U:X"#-.5K!-\V5K,<-_Z:L_UZ^WW
MNZC50J)WRQE@E\E>KV>R!Y@=39>`8AH'B]UJQDV:,Q0-I[-=PYR>R8DB8@L?
MI9L:7)Q9NQB^ALZ'/:5#UW?A(_K>J.O\#4WA&,6R82V9+$F.;4"42>%"*;2Y
ML,GEO#>700Q";W>WG8#U<4LB!K^+HZN1U'\*PJG5"W-]P,?F:QT('MCNK1^6
MH\Y;I$^8RLS'@UA<]O;Q+[5(S?[6JD?5Q,4Z^F4W(.Z9MNZR_P^0S&_>-(FD
$*P@`````
`
end
Alberto
