> > Date: Fri, 11 Aug 2017 17:22:58 +0100 > From: Rod Smallwood <rodsmallwoo...@btinternet.com> > Subject: pdp-8/e restoration update. > > Hi List > > Well I think I've found why the RX01 is not responding. > > The device address (75) is not getting decoded on the controller because > the CPU does not assert BUS I/O PAUSE L > > Which it should do I think when it sees an IO instruction. > > Do I have this right? > > Rod Smallwood >
Yes, you have it right. Take a look at E7 pin 6 in the M8330 Timing Generator. It is in section C2 on the prints. It decodes the instruction 6xxx, USER MODE H, and I/O TIME (1) and drives I/O PAUSE low. -- Michael Thompson
