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RE: DECstation rtc driver

To: Ralf Baechle <ralf@uni-koblenz.de>
Subject: RE: DECstation rtc driver
From: Harald Koerfgen <Harald.Koerfgen@home.ivm.de>
Date: Tue, 28 Mar 2000 17:22:40 +0200 (MEST)
Cc: linux-mips@fnet.fr
In-reply-to: <20000327223734.A3523@uni-koblenz.de>
Organization: none
Reply-to: "Harald Koerfgen" <Harald.Koerfgen@home.ivm.de>
Sender: harry@franz.no.dom
On 27-Mar-00 Ralf Baechle wrote:
> The DECstation RTC driver has the following lines of code
> 
> [...]
>         } else if (year >= 70 && year <= 72) {
>                 epoch = 1928;
>                 guess = "Digital DECstation";
> [...]
> 
> around line 676.  This means that only two the years 1998 to 2000 will be
> recognized for the `Digital DECstation Epoch'.  Looks broken to me.  I
> tried to fix it but don't know the secrets of DECstation RTC timekeeping so
> could a DECstation guru look at it?

Sad, but true. The DECstation engineers, in their infinite wisdom, decided to
use the RTC chip as a TOY (Time Of Year clock) and as such the BootPROM allows
only the years 70..72 as valid values (70 for even years, 71 for odd years, and
72 for leap years).

Otherwise you'll get a self test failure and the date will be reset, as Maciej
already pointed out. And yes, this code has to be modified every two years :(.

-- 
Regards,
Harald

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