Driving the Real Time Clock

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3 total messages Started by mhw Mon, 09 Nov 1992 11:20

#313

Author: mhw
Date: Mon, 09 Nov 1992 11:20

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Can someone tell me the part number of the real time clock/non-volatile
RAM chip used in the A3xx and A4xx series machines and suggest where I
might be able to get hold of data sheets from? Are the same parts used
in the newer machines (i.e. A5000 and co.)?

Thanks,

-Mark.

Re: Driving the Real Time Clock

#358

Author: Alan Williams
Date: Wed, 11 Nov 1992 14:50

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In article <721308024.4228@minster.york.ac.uk> mhw@minster.york.ac.uk 
writes:

>Can someone tell me the part number of the real time clock/non-volatile
>RAM chip used in the A3xx and A4xx series machines and suggest where I
>might be able to get hold of data sheets from? Are the same parts used
>in the newer machines (i.e. A5000 and co.)?

Its a PCF 8583 and it comes from Philips, at least the data book I have does.  
The whole IIC chipset fills two hefty volumes and includes some quite 
remarkable devices.  It makes fascinating reading.  I have done a bit of work 
driving IIC from my Model B if you ever want 6502 code to do it! 

I am interested by the suggestion made recently in this news group, that this chip 
may have a mode where it becomes an 'engine hours' counter rather than a RTC.  
I have a customer who is reporting exactly these symptoms for his machine I 
will be rather pleased if I can find a soft fix.  Power on R sounds like a good 
start.  I am going home to night to read the data book!

I think that its the same chip in all machines ( except being in an smd pack these 
days) , the A4 loads a different IIC module so that may be the odd one out.

Alan.

The views expressed are my own and are not necessarily those of Acorn.

Re: Driving the Real Time Clock

#400

Author: Stuart Tyrrell
Date: Thu, 12 Nov 1992 15:18

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mhw@minster.york.ac.uk writes:

>Can someone tell me the part number of the real time clock/non-volatile
>RAM chip used in the A3xx and A4xx series machines and suggest where I
>might be able to get hold of data sheets from? Are the same parts used
>in the newer machines (i.e. A5000 and co.)?

Yes, the chip is a Philips chip no PCF8583. The details are available in
the general philips data book range (I think it's book 4 - the one on IIC
products anyway!). If you are at an academic institution, the electronics
dept should have them somewhere! or try the library.

Hope this helps,

Stuart.

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