[TUHS] v6 RK05 bootloader question

Noel Chiappa jnc at mercury.lcs.mit.edu
Thu Dec 31 23:45:23 AEST 2015

    > From: Wolfgang Helbig

    > The HALT instruction of the real PDP11 only stops the CPU 

I have this bit set that on at least some models of the real machine, when
the CPU is halted, it does not do DMA grants? If so, on such machines, the
trick of depositing in the device registers directly would not work; the
device could not do the bus cycles to do the transfer to memory. Anyone know
for sure which models do service DMA requests while halted?


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