🚀 go-pugleaf

zrepachol@cc.curtin.edu.au writes:

>In article <BznHn7.A5F@world.std.com>, mbg@world.std.com (Megan B Gentry) writes:
>> mfroedge@lunatix.uucp (Maxwell Froedge) writes:
>...
>> 	There are two things contributing to whether your
>> 	system is 18-bit or 22-bit.  First, the CPU.  If you
>> 	have a KDF11-B (quad-high module), you have 22-bit
>> 	support on-board.  If it is a KDF11-A (rev.c), you
>> 	also have 22-bit support.  KDF11-A (rev.a) is 18-bit
>> 	only.

>Bzzt, wrong. The rev c KDF11-A was the only 18 bit CPU in the 23s, despite
>DEC propaganda of the time. ( "No, you have to pay $$$$ for a 23+ for that... ")
>You will also have to chuck any 18-bit memory or controlers if you want more
>than 128KW. Note, 128, not 124. You can have all 128KW in a Qbus.

Sorry, I have a KDF11-A (rev.c) which has MUCH more than 128kw on it
at home...  The KDF11-A (rev.c) carried the extra four addressing
lines out to the bus, where the rev.a had not.  The rev.a could
only address 18-bits because those addressing lines stopped on-board.

(I seem to remember someone hacking a rev.a board so that the extra
four lines were carried to the bus, but I don't remember who.  I think
the lines had to pass through inverters first.)

					Megan