PDP 11/23 help needed

From: Allison J Parent <allisonp_at_world.std.com>
Date: Wed Apr 22 18:12:39 1998

<Um... Am I way out here? Doesn't the 23 support 22 bit addressing? And

The basic M8186 early revs are 18bit but most work as 22bit, the later
revs were 22bit. That's assuming the backplane is wired for 22bit as
well.

<I never before heard of a 16 bit Qbus! ISTRT the F11 processor is

LSI-11/03 cpu and box. The backplane was wired for only 16bit addesses.
Also that particular CPU put some of the microcode signals on what would
have ben the A16-21 lines.

<settable between 18 and 22 bit (128KW, 256KB and 2MW, 4MB respectively).
<The 18 bit setting is used in the 23 on 18 bit Qbuses and in the 24 on
<unibuses. The 22 bit setting is used on 22 bit Qbuses, but you need
<extra hardware to use it in the 24 (i.e. on unibus).

Your thinking of latter machines with specific backplanes.

Allison
Received on Wed Apr 22 1998 - 18:12:39 BST