On 11/29/16 1:24 PM, Charles Dickman wrote:
On Tue, Nov 29, 2016 at 12:54 PM, Toby Thain <t...@telegraphics.com.au> wrote:
On 2016-11-29 12:22 PM, Noel Chiappa wrote:
> From: Peter Coghlan
> Can anyone suggest an existing, simple QBUS device that I could
study
> the documentation of to figure out what a basic QBUS device needs to
> have and to give me some ideas on how to implement one?
Depends. Do you want to be able to do interrupts? Do you want to be able
to
do DMA? Each is a significant increment in complexity.
Later DEC QBUS devices may not be the best things to look at, since they
tend
to use special DEC QBUS control chips (I'm _not_ talking about bus
transceiver chips here) which are of course no longer available.
The DEC Chipkit documentation has the internal schematics for the
standard DEC interface chips and is very much worth a read.
The major advantage of using chipkit parts is space. If you build on a
quad wide board
then its fairly easy to do DMA, bus arbitration, interrupt chain, and
interrupt vectors
as its all documented in the various Qbus PDP-11 books.
About the only thing I've done is simple parallel interfaces as any
other function
was available built. Though one of these days a CF "disk" board with
boot rom
would be handy. that would make a 11/23, dlv11j, memory and self contained
disk card a nice 4 board system in a BA11-VA box.
Allison
