10 Mar
2013
10 Mar
'13
5:39 p.m.
On 03/10/2013 02:32 PM, Ian Finder wrote:
Hi everyone,
I recently obtained a box of stuff.
The box appears to contain a complete 11/23 boardset!
I've wanted a PDP 11 for some time, so needless to say, it would be great
to make an actual PDP 11/23 out of the boards.
My options appear to be purchasing a complete chassis with a backplane,
power supply, and IO-- or alternatively building my own replacements for
these parts.
The key item is a backplane, they are around so find one rather than
trying to make one.
Boxes complete are not that much harder to find though the PS may
need to be checked/repaired.
Power supply is +12, -12, +5 and has AC-low, DC-LO and BEVENT (for 50/60hz
real time clock used in most all in software). PC supply does not do
all this.
Candidates, BA11 series, BA23, BA123. Heathkit H11 also was compatable
though it was only Q16.
Qbus came in three forms, Q16 used for the first machines with LSI-11 cpu.
Later were the Q18 (18bit wide address bus) and Q22 (22bit wide address
bus).
The Q22 is preferred but the earlier ones can have wires added to make
them Q22.
FYI and BIG suggestions find a copy of the "PDP-11 Microcomputer
Handbook" (digital Equipment corp press)
one from the 1981 to '87 time frame is handy to have. You will learn
DEC terminology and they
contain important programming and configuration information.
Are chassis something that pop up from time to time? Are there multiple
models that will take this board set?
If its Qbus it's likely a suitable
candidate.
Geography defines how easy it is to find stuff. Here in MA I tend to
trip on it
and I could not even give it away. In foreign countries not so much
L'll bet.
Alternatively, is the backplane something fancy
I'd be unable to roll my
own of?
Not a reasonable task. Connectors are scarce, expensive, and accurate
placement is a big thing.
Allison