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TEKTRONIX-4662-AND-4663-PEN-PLOTTERS [??-???-8?]

 The installation of <PLOT79> on the Chemistry DEC VAX-11/780 in January
 resulted in a new device interface for the Tektronix 4663 pen  plotter.
 This plotter has 2 pens and a respectable 10 inch/second drawing speed,
 with a C  size drawing surface  (about 17  in x 22  in, with  available
 drawing area  15.5  in  x  20  in),  optional  paper  feed  attachment,
 X-on/X-off protocol, and a large number of switch-settable options  for
 pen pressure, speed, and type,  paper format, aspect ratio  adjustment,
 mirror imaging, and so on.  The 4663 has a list price of about $11K.

 Regrettably, the plotter  has two serious  misfeatures.  First of  all,
 although it accepts the  normal Tektronix command  format used for  the
 401x storage-tube terminal  series, it  must first be  "selected" by  a
 special command sequence, which it must receive on its serial line, not
 via its wonderous bank of option switches.  Thus, it is not possible to
 directly send it a plot file produced from one of the 401x  interfaces.
 The alternative  of always  sending it  two plot  files, one  with  the
 select sequence,  and one  with the  plot commands,  is too  much of  a
 burden on the  user (although  an output spooling  system could  easily
 manage it).  Also, use of the 401x interface does not permit access  to
 the pen change commands.  The second misfeature is the great difficulty
 in setting the  plot size.   The 4663 automatically  rescales the  401x
 device coordinates (0..1023  or 0..4095)  to whatever  the viewport  is
 currently set at according to the option switches and corner  positions
 set by the  joystick.  The switches  allow selecting the  large C  size
 format, an intermediate B size, and the American standard A size (8.5 x
 11 in).

 Unfortunately, the plotter  puts the viewport  somewhat inside each  of
 the paper sizes; in the case  of the A size, a  10.5 x 7.74 in area  is
 available.  The aspect ratio  of the B size  is different from that  of
 the A and C sizes, which results in a plot which fit in the A or C size
 being clipped in the B size.  The  forced margins in each of the  paper
 sizes prevent  use  of  the  full  page,  and  the  possible  arbitrary
 positioning of the  viewport via  joystick action  make it  exceedingly
 difficult to make  a plot of  a specified size.   We wasted many  hours
 attempting to find the magic combination  of events which would let  us
 guarantee the production of  a synthetic spectrum  plot of exactly  the
 right size to overlay an experimental one.

 In fairness, the  4663 DOES  have a mode  in which  coordinates can  be
 transmitted in  millimeters,  but  then a  totally  different  software
 interface is required.

 The Tektronix 4663  has a little  brother, the 4662  (list price  about
 $4600), which has a 8.5 x 11 inch surface, with the available  plotting
 area again somewhat inside this.   Once again, joystick positioning  of
 the viewport makes it almost impossible to guarantee the production  of
 a plot  in  a desired  aspect  ratio and  scale.   The 4662  lacks  the
 X-on/X-off protocol,  so  driving it  at  an acceptable  speed  without
 buffer overflow requires a painful  tuning process.  Despite claims  in
 the manual to compatibility  with the 401x  terminal plot commands,  we
 found that it raises an error condition on finding the padding NULs  in
 the 401x plot  files which are  necessary to prevent  data loss on  the
 screen terminals.  It has thus been  necessary to write a special  copy
 utility which discards NULs and periodically takes a short nap to avoid
 overflowing the 4662 buffer.  The 4662 does accept an alternate command
 format  in  which   checksummed  blocks  of   commands  are  sent   and
 acknowledged,  but  use  of  this  would  require  yet  another  device
 interface.   Altogether,  I   find  both  of   these  plotters   rather
 disappointing and annoyingly poorly human engineered.