Boot rom chip select!!

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Hi all,


Can anybody give me some idea..
what is the basic difference b/w Boot chip select and normal chip select for a
microprocesor/microcontroller.
If I am not wrong boot cs :
Restricts itself to a  fixed start and end address of memory.
Default it always remains enabled.  

What are the other special things about boot cs?

Any help will be highly helpful...

Thanks and best regards
Paraveen deshpande

Re: Boot rom chip select!!

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It depends on the specific processor.

Pretty often it's the chip select corresponding to the startup address of
the processor. In processors with programmable chip-select units it's the
only chip select alive at reset. The idea is to put a fixed memory (e.g.
Flash) with suitable code behind the boot chip select, so the chip select
unit can be set up at startup.

For examples, get e.g. data sheets for Intel 80186 and Atmel AT91x4xx.

HTH

Tauno Voipio
tauno voipio @ iki fi



Re: Boot rom chip select!!
snipped-for-privacy@rediffmail.com (Praveen Deshpande) wrote in message
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  This is based on Motorola's scheme as used in the 68HC16 and 683xx
CPUs.
The boot CS is available at device reset, read-only, of a fixed size
and timed for slow memory, like EPROM. The memory-width (8 or 16 bits)
is selected by pulling a data-line (#?) low during reset.
 After start-up, the chip-select's timing, address-range and width can
all be changed by software.
Wade Hassler

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