piclist 2000\04\21\022927a >
Thread: Disable Interupts While Accessing Bank 1,2,3 Ram ?
face BY : Mike Morris email (remove spam text)

<x-flowed>The simplest thing to do (for the '877) is define the context save register
for W in the upper 16 bytes of the GPRs since they are common to all 4
banks. Then it doesn't matter which bank you are in when you save W in your
interrupt service routine. If you don't use a location in the upper 16
bytes, then you have to make sure you allocate a 'w saving' register at the
same offset in all the banks, since you usually don't know which bank
you'll be in when an interrupt occurs. Interrupts while in any bank is no
problem as long as your context saving/restoring works properly. Just
follow the example in the '877 data sheet. Define w_temp in the upper 16
bytes of bank 0, and everything will work fine (well, as far as context
saving.  :)

- Mike

At 11:22 PM 4/20/2000 -0500, you wrote:
{Quote hidden}


In reply to: <000501bfab49$427b4380$57315d18@austin.rr.com>
See also: www.piclist.com/techref/mems.htm?key=bank
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Subject (change) Disable Interupts While Accessing Bank 1,2,3 Ram ?

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