From mboxrd@z Thu Jan 1 00:00:00 1970 From: jnc@mercury.lcs.mit.edu (Noel Chiappa) Date: Thu, 31 Dec 2015 08:45:23 -0500 (EST) Subject: [TUHS] v6 RK05 bootloader question Message-ID: <20151231134523.33F9318C0D5@mercury.lcs.mit.edu> > 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? Noel