Re: [avr-gcc-list] one-byte stack bug in tiny26

[Bob Paddock]

On Tuesday 27 April 2004 05:51 am, Marek Michalkiewicz wrote:

> > According to the datasheet, the register of SPH is reserved.

> Well, it worked long time ago - non-existent SPH was read as zero.

"Reserved" registers should not be read in any case, ever.

Reserved does not necessarily mean "unimplemented".

Frequently "Reserved" registers are used for internal test functions when
the chip is made.  Some manufactures will tell us about  that, others do not.

Accessing the "Reserved" registers can get the chips in to peculiarly test 
modes not consistent with the data sheets.

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