A smaller display is available. This display uses a five inch, high resolution cathode ray tube. The tube is equipped with a mounting bezel to accept a camera or photomultiplier device. The operation of this display is similar to that of the 16 inch, except that 12 bits are decoded for each axis.
REAL TIME CLOCK
A special input register may be connected to operate as a Real Time Clock. This is a counting register operated by a crystal controlled oscillator. The clock can be reset to zero by manual operation. A toggle switch interlock prevents an accidental reset. The state of this counter may be read at any time by the appropriate In-Out Transfer instruction.
LINE PRINTER
A 72 column Anelex printer and control are available as an option for PDP-3. The control contains a one line buffer. This buffer is cleared by the completion of an order to space the paper one position (psp). The buffer is filled from the In-Out Register by a succession of 12 load buffer orders (plb). The first plb will put the six characters represented by C(IO) in the leading (left-hand) column positions of the buffer. After the buffer is loaded, the order, print (pnt), is given.