They still have the shell of a Cray machine as a museum exhibit, along with various other bits and bobs. The Atlas building is still there, and still has computing hardware in it.
It has all moved on to become arrays of Linux machines with petabytes of disk, but it is a tier 1 storage for CERN now.
From: piclist-***@mit.edu [mailto:piclist-***@mit.edu] On Behalf Of David C Brown
To: Microcontroller discussion list - Public. <***@mit.edu>
I must be the only seventy year old computer engineer who doesn't have fond memories of using a PDPx.
I moved straight from simple lab work to the ATLAS and MU5 computers: the two largest computers in the country at the time.
Post by Harold HallikainenInteresting! The first community college course I taught was assembly
language programming on the PDP-8. We had a Teletype with paper tape
punch. You'd use the front panel switches to key in a loader. You'd
then run a tape through that would load another loader. Then run
another tape to load an editor. Type in the source code and output to
tape. Load the assembler from tape. Run the source tape through twice
(two pass
assembler) to get an object tape. Load the object tape and debug using
toggle switches and lights on the front panel.
I still have the book I used for the class. I remember one of the
instructions was CIA for Complement and Increment Accumulator (two's
complement the accumulator).
One interesting thing about the PDP-8 was the way it handled subroutines.
It did not have a stack pointer. If you did a subroutine call to
0x1000, the return address was stored in 0x1000 and execution would
start at
0x1001 (actually, everything on the PDP-8 was octal instead of hex,
but you get the idea). The last instruction in the subroutine was an
indirect jump back to the beginning of the subroutine. The return
address would be fetched and loaded into the program counter. Execution continued.
At that time I also taught PDP-11 assembly language programming. I
always thought the instruction set of the PDP-11 was very clever. An
instruction consisted of the operation, the source register, the
source mode, the destination register, and the destination mode. Modes
included direct, indirect, predecrement, post decrement, preincrement, postincrement, etc.
The program counter and stack pointers were "just another register."
Putting something on the stack was just a write to the stack pointer
indirect post decrement. A literal used the program counter as the
source register with a post increment. After the instruction had
loaded, the PC was already pointing to the literal data, so it was
read, then the post increment to point to the next instruction.
Anyway, I thought it was all very clever. This was back in the 1980s.
I ended up teaching part time for 25 years, mostly hardware, but
started with PDP-8 assembly language programming.
Harold
Post by CDBAn article from RS components about a Raspberry Pi kit that looks
similar too and operates like a PDP 8.
https://www.rs-online.com/designspark/my-raspberry-pi-
thinks-its-a-pdp-8?cm_mmc=AU-EM-_-DSN_20180226-_-DM89749-_-
HB_URL&cid=DM89749&bid=605967082
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