Re: [comp.sys.cbm] New commodore hard drive controller

From: Asbjørn Djupdal (
Date: 2002-08-22 11:19:42

> > But I can't see how to get rid of the 7406 chip.
> That's pretty simple. You can use the AVR portbits like they were open
> collector outputs: set the respective output bits (PORTD.0 and PORTD.1)
> to '0's, and activate them using the data direction register when it's
> neccessary (DDRD.0 and DDRD.1). With DDRD.0 =1, the pin is output (= a
> strong 0 level), with DDRD.0 = 0 the pin is input ( = the pin is left
> floating) and you can read its value from PIND.0 . That's probably all
> about it.

Thats clever. I didn't think about it. I just looked at the 1541
schematics where they use a 7406 :)

> BTW, if it were smaller, it could call for a CompactFlash as media,
> rather than an old IDE HDD. If something at all, I especially like the
> noiseless operation of these old computers.

A good point. 


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