Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!RITVAX.BITNET!DGR0093
From: DGR0093@RITVAX.BITNET
Newsgroups: comp.sys.apple
Subject: RE: Clock cards and Prodos
Message-ID: <8805010007.aa15125@SMOKE.BRL.ARPA>
Date: 1 May 88 07:06:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 32

NOTE: I tried posting this earlier, but somehow only the inclusion from
the note I was replying to got back to me, so I assume everyone else got
the same fragmented version. So here's another try at it...

> Can anyone tell me how Prodos interfaces with a clock card?  I have (I think)
> the chips necessary to construct a card but would like to know what addresses
> Prodos looks at to get the time and date.  I suppose what I'm really after is
> a memory map of the Thunderclock card.  Can anyone help?  Thanks in advance.

I think you could do it by having your card (I don't know much about hardware
interfacing on the level you're doing, so I don't know if this method is
actually possible) update the date and time in locations $BF92-93 for the
time, and $BF90-91 for the date. The bytes hold the date and time information
somewhat encoded, though, so I here enclose an example I get from the Beagle
Bros. Pro-Byter manual:

Date Bits: YYYYYYYM MMMDDDDD (bytes in reverse order)
Time Bits: HHHHHHHH MMMMMMMM    "   "   "   "   "

EXAMPLE: 25-Jan-42 06:42 [I don't know why they used 42, but they did.]
Appears in memory as such:
BF90:39 54 15 06
Swap the order to get: 54 39 and 06 15
Date Bytes: $54         and $39
     Bits : 01010100        00111001
    or Year 0101010, month 0001, day 11001
    or Year 42, month 1, day 25
Time Bytes: $06         and $15
     or Hour 6, minute 21

Hope this is what you're looking for. Have fun and good luck...

Dave Rutherford a.k.a. Michelangelo H. Jones            DGR0093@RITVAX.BITNET