Cheshire's PDP-11. The cabinet claims it's a PDP-11/03, but it has been long since upgraded with a CPU from a PDP-11/73. I believe it has 4 MB of RAM (which would be the limit due to the 22 bit address bus on the QBUS and the J-11 CPU chip set), but the architecture limits the address space of any single process to only 64 KB. My first introduction to an MMU was to divide a large physical address into many small logical addresses. These days, MMUs are usually used the other way around.

It was originally put into service in 1983 and is still operational. It runs the TSX-11 timesharing system over an RT-11 kernel.

Also on the QBUS are a pair of third party co-processor boards, each with 4MB of linear addressed DRAM, one with an intel 80486 (the XP-11) and the other with a Motorola 88000 (sometimes known as the YP-11). We used a Greenhills C compiler hosted on the co-processor to build utilities that needed larger address spaces as well as more raw CPU power.

Also in the rack are 5.5" and 8" floppy drives, the hard drive, and a 9 track tape drive. The whole thing would fit in one 4foot tall rack, but we got a good deal on two...

The minitower sharing the hollow at the right is a Pentium 2 PC running Win2K.

The lower right corner is missing because this photo has been substantially corrected for perspective in Photoshop and the pixels just weren't present in the original image. The alternative would have been to change lenses to something wider so that I could have put the camera directly in front of the rack, but it isn't in a very large room and the wide angle lens I have available is a lot slower than the 50 I used for this shot.