Serial Number AG19054
The 11/04 was a mid/late-70s implementation of the Unibus pdp-11 architecture, and was essentially a replacement for the 11/05 & 11/10. It was the first pdp-11 to escape without a 'proper' lights & switches front panel, instead it had the glorified 'programmers console' as an option - a hex keypad and an LED display which showed address/data digitally.
It came in two chassis, like the 11/05 & 11/10 - a half-height example, which had the entire Unibus backplane, power supply, front panel - basically the whole computer - sliding into an evil jamming finger-trapping metal sleeve - and a full-height example, basically the same BA11 box as used by the 11/35 and many many other DEC applications. It's very similar to its higher-spec twin, the 11/34.
My 11/04... ok I have to confess; it was bought on ePay. OK OK, it was cheap and I didn't have one... I had a couple of the half-height 11/04 machines a few years ago, but I traded them for something more interesting...
The somewhat disappointing front panel.
Standard BA11 box...
Inside, single-board CPU (M7263), programmers console (front panel) interface (M7859), Unibus bootstrap/terminator (M9312), two MOS memory stacks (M7847-DJ 16KW / 18-bit), RS232/20MA console interface (M7856), and a 3rd party disk controller (SMS FD1100I) - looks like a floppy cable for a ?8" floppy disk?.
Can't find any information on that SMS FD1100I disk controller - if you know anything about it, please get in touch
Lots of folks have 11/04s, so I won't try to exhaustive in listing them!
http://members.optushome.com.au/intaretro/PDP11.htm This chap in Australia has some nice pictures showing the 'half-height' 11/04 chassis...
http://telnet.hu/hamster/pdp-11/1104.html ...and this Hungarian site shows an 11/04 without the 'programmers console'.