[geeks] WOOHOO!!

[Dave McGuire]

   I had to get away from QYXie stuff a bit because it was driving me 
insane.  It's taken me nearly two days of work with schematics, an 
oscilloscope, and a multimeter, but....

   Wait for it...



   WAIT FOR IT.....




   My PDP-11/70 just booted RT-11!!

   For you weirdos who don't know what a PDP-11/70 is (though I'm sure 
everyone here has at least heard of them), it's the biggest, baddest 
PDP-11 ever built...the granddaddy of 'em all, circa 1974.

   There are a few large pics of various parts of it, taken late last 
night, at http://www.neurotica.com/pics/pdp1170/.

   The panel with the LEDs and switches is the processor, the 10.5" bay 
to the right of it (with the white vented front cover) is the MK11 
memory subsystem (1.5MB), best seen in DSCN1153.JPG.  Below the MK11 
(with no cover, with the big yellow warning label, best seen in 
DSCN1155.JPG) is the old MJ11 core memory subsystem (dunno how much 
yet) that was in the system when it was originally purchased in 
1975...the MK11 (semiconductor memory, type 4116 DRAM chips) was added 
as an upgrade later...lower power consumption, faster, and more 
reliable than magnetic core.

   Just below the MJ11 core subsystem and above the rightmost power 
controller, there's a little rectangular panel.  That's the memory 
subsystem control panel...from four thumbwheel switches and three 
toggle switches, you can control power to the memory subsystem, set its 
starting address and interleave, and enable or disable ECC.

   The board in DSCN1154.JPG is a memory array board from the MK11 
memory subsystem, and the board in DSCN1169.JPG is an RL11 disk 
controller for RL01 or RL02 drives like the one in the upper leftmost 
spot in the racks.

   The TE16 magtape drive on the right isn't connected yet because I 
don't have a MASSbus cable for it.  I'm looking for one now.

   The processor itself can be seen in DSCN1164.JPG as the large group 
of boards toward the right of the backplane.  The other side of that 
backplane, with its miles of wiring, can be seen in DSCN1161.JPG.

   I first read about the design of this particular member of the PDP11 
family while sitting up way too late on a school night, reading in my 
bed with a flashlight, hoping my grandmother wouldn't bust me.  I 
remember thinking "My GOD...cache memory...22-bit address 
bus...microcode single-stepping capability...I'll *never* be able to 
get one of those!" ...I was 13, that was twenty years ago.

   This is a really, really big deal for me.

        -Dave

--
Dave McGuire                  "Mmmm, big."
St. Petersburg, FL                -Den