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RTC card

A project log for Going 8-bit in style: the PIC18 computer

My attempt to create a fully expandable 8-bit system built around a modern architecture

KnivDKnivD 07/19/2019 at 09:223 Comments

This one is done "the proper way" :)  Not I2C or SPI, but with address decoding and mapped into the main address space. Unfortunately there are not many manufacturers who still make RTC ICs with parallel bus. In fact, except Maxim there are hardly any others. Fortunately this good chip from TI is perfect for the need. Not the cheapest option on the market, but still bearable price.

Sending this one the factory way too, for prototype PCBs.

Discussions

Ken Yap wrote 10/19/2019 at 23:24 point

Given the low bandwidth requirements of a RTC I don't think I would spend money for an uncommon chip and board+slot space just for a RTC when I2C RTCs can be had for just over a buck with battery holder included.

Of course it does bring back the nostalgia of add on RTC cards for CP/M and early DOS micros.

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KnivD wrote 10/20/2019 at 14:05 point

I agree, but the point is not how cheap it can be made

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danjovic wrote 10/19/2019 at 22:54 point

I2C is vintage 8bit friendly as long as you do it banging bits, lol!

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