1802 problems

J.C. Wren jcwren at jcwren.com
Sat Dec 31 21:20:24 CST 2005

    Tony, could the 1802 be in LOAD mode (CLEAR low, WAIT low)?  You'll 
get DMA-IN cycles in that mode.

    "LOAD: Holds the CPU in the IDLE execution state and allows an 
device to load the memory without the need for a "bootstrap" loader. It 
modifies the IDLE condition so that DMA-lN operation does not force 
execution of the next instruction."


Tony Duell wrote:

>>Oh, also the SC0/SC1 states are only valid on TPA.  Does your datasheet 
>>call that out?
>Thanks, no I'd not spotted that. Tomorrow (it's getting late...) I will 
>see (a) which states it is going into and (b) if the pulse on SC1 occurs 
>coincident with TPA. And so on.

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