Subject: Byte offsets in Q-bus map registers?
To: None <port-vax@NetBSD.ORG>
From: John Wilson <firstname.lastname@example.org>
Date: 02/04/2000 13:08:29
I have an annoying hardware question:
Can anyone tell me whether Q-bus MicroVAXen typically support byte offsets in
DMA map registers? E.g. on a VAX-11/780, setting bit 25 (the "byte offset"
bit) of a map register allows a Unibus device to do word transfers to that
page at odd physical memory addresses, even though Unibus word addresses
are always even. Do MicroVAX machines have the same capability or do Q-bus
word DMA transfers have to go to even addresses like on a PDP-11? Or does
it vary from one model to another?