[cctalk] Re: Address wrapping in PDP-11 MMU

2023-11-17 Thread Martin Bishop via cctalk
OK, a faux descriptor would work round the documented checks which are on block number rather than EA - there is a hardware overide I'm delighted to hear that RSTS won't play along and set up for EA overflow Martin -Original Message- From: Paul Koning [mailto:paulkon...@comcast.net] Se

[cctalk] Re: Address wrapping in PDP-11 MMU

2023-11-17 Thread Paul Koning via cctalk
Ok, but I think that's not what I meant. Suppose I have APR6 = 17 and length > 1. That means VA 140076 maps to physical address 1776, and VA 140100 maps to physical addres 2000 which when masked with 22 bits would end up at 0. The offset within the page is <= the page length. Mea

[cctalk] Re: Address wrapping in PDP-11 MMU

2023-11-17 Thread Martin Bishop via cctalk
EK-DCJ11-UG-Pre DCJ11 Microprocessor User's Guide says it will abort [the first processor guide on the shelf] $4.5.2.2 (p4-7) Page Length Field ... "The block number of the virtual address is compared against the page length field to detect length errors" ... $4.7.1 MMR0 <14> Abort Page Length