6 Jan
2011
6 Jan
'11
2:18 a.m.
2011-01-04 17:14, Pete Turnbull skrev:
In the 11/23 the bootstrap is on the BDV11 card if I haven't
misunderstood. Is the MXV11 an equivalent or a more modern card?
I seem to lack one crucial part for my 11/73 system then.
I have a BA23 (with space for drives that slide out in front) I don't
know what backplane (it is in storage now). The CPU is the dual-height
M8192. I got the chassis and CPU from different places.
- Pontus
M8047: MXV11 -
probably a 16Kword card w/SLUs - also small for a
large system
It's an MXV11-A, which won't have a proper diagnostic bootstrap for an
11/73 (it won't initialise everything properly for a KDJ11). You need
an MXV11-B for a KDJ11, and the ROMs aren't interchangeable (paging
hardware works quite differently). It also only supports 18-bit
memory addressing, so it would limit what else you could use. Every one
I've seen can work in an 18-bit or 22-bit chassis. That's the
limiting factor - what's your backplane? A post-rev-A KDF-11 in a
BA23 has no problems with being configured as a 22-bit system. It's
also possible to run wires to upgrade an 18-bit backplane to 22-bits -
many of us on the list have done that.
Yup, I did that to all mine, years ago. The other thing to check is
exactly what backplane you have in the 11/73. Is it an 11/73 in a
BA11 box (looks like an 11/03 or 11/23)? Or is it a microPDP-11/73 in
a BA23/BA123 box? Check, for they have different backplanes! And is
the 11/73 a dual-height (M8192) or quad-height (M8190) card? The
dual-height ones were often used as upgrades for older 11/23 systems,
but were also sold as 11/73S systems in a BA11-S box. A
microPDP-11/73 is always a BA23 or BA123 box, but the quad-height
boards were sometimes used as upgrades to 11/23plus systems in BA11
boxes.
See http://www.dunnington.u-net.com/public/PDP-11/QBus_chassis