00100	    A DISPLAY TERMINAL SYSTEM FOR THE COMPUTER SCIENCE DEPARTMENT
00200	
00300	
00400		This  is a plan to equip the Computer Science Department with
00500	a system of keyboard and display terminals for use  in  teaching  and
00600	research.   The  terminal  system  will make accessible to department
00700	faculty and graduate students from their offices the  IBM  360/67  in
00800	the  Computation  Center,  the  PDP-10 in the Artificial Intelligence
00900	Laboratory, and through the PDP-10 any computers on the ARPA  network
01000	that  they  may  have  made  arrangements to use.  This includes, for
01100	example, the ILLIAC 4 at Ames Research Center.  Connections to  other
01200	campus computers can also be arranged.
01300	
01400		In our opinion, such a terminal system together with suitable
01500	hard copy output  in  the  most  important  laboratory  and  teaching
01600	facility  that a computer science department can have.  The interests
01700	of the faculty and students are too varied to be satisfied by any one
01800	computer  since  no  one  computer  will  have  all  the hardware and
01900	software facilities that are of research or teaching interest.
02000	
02100		The plan we are now proposing is based in  part  on  a  study
02200	made  by John McCarthy at M.I.T. in fall 1972 in support of a plan to
02300	get a terminal system for Project MAC and the Artificial Intelligence
02400	Laboratory.  In  this  study,  requests  for  proposals  were sent to
02500	leading firms in the display field and the  replies  were  evaluated.
02600	The  best  plan,  however,  was found to be scheme being developed by
02700	Peter Wiener of Yale University, and our plan is based  on  the  Yale
02800	scheme  which  is  also  being  followed  by  the  M.I.T.  Artificial
02900	Intelligence  Laboratory.   The  Stanford   Artificial   Intelligence
03000	Laboratory  also hopes to upgrade its Data Disk display system to the
03100	new standard.
03200	
03300		The goals that we want to achieve are the following:
03400	
03500		1. A terminal in each office used  by  faculty  and  graduate
03600	students. This requires very low cost terminals.
03700	
03800		2.  A  large  terminal  facility  for  the use of students in
03900	courses. About  half  the  terminals  would  be  available  for  this
04000	purpose.
04100	
04200		3.  Each  terminal  should  be capable of displaying at least
04300	half a page of arbitrary  character  sets  and  also  graphics.   The
04400	character   sets   used   in  programming  and  in  mathematics  have
04500	proliferated to the point where allowing each user to  have  whatever
04600	characters  he wants is the only solution compatible with the goal of
04700	using any computers that are available to our faculty and students.
04800	
04900		4. Printing facilities compatible with the above should  also
05000	be  available but not necessarily with each terminal.  In fact, there
05100	is no present  way  of  making  such  facilities  available  to  each
05200	terminal  but  suitable  public  printers can be had, for example the
05300	Xerox XGP. The cost of  adding  such  a  printer  has  not  yet  been
05400	determined, but there is a strong demand for it, and its cost will be
05500	included in a future version of the plan.
05600	
05700		The scheme proposed has the following characteristics:
05800	
05900		1. The display image for each active  user  is  stored  as  a
06000	512x512 raster in an integrated circuit read-write memory.
06100	
06200		2.  There are 64 terminals, but only 32 memories so that only
06300	half of the terminals can be active simultaneously.  However,  a  low
06400	duty  cycle is to be expected if the terminals are in offices so this
06500	is ok.
06600	
06700		3. The cost to add a terminal to the system  is  about  $500,
06800	and  the  cost  to  add  a  memory  is  about  $2200 now, but a large
06900	reduction is expected in less than two years as 4096 bit memory chips
07000	come  into  production  replacing  the  1024  bit  chips on which the
07100	present prices are based.
07200	
07300		4. The system is controlled by a mini-computer, say a PDP-11,
07400	which  communicates with the host computers (initially the IBM 360/67
07500	and the PDP-10), and  writes  characters  and  pictures  by  directly
07600	addressing  the  display  memories.  The displays are maintained by a
07700	memory port that reads bits from the memories  into  shift  registers
07800	and  transmits  them  together with synchronization signals through a
07900	video switch to the displays over coaxial cable.
08000	
08100		5. Each display is connected to the central  unit  containing
08200	the  memories by an individual cable, and the keyboards are connected
08300	to the keyboard multiplexer by twisted pair unless it turns out to be
08400	feasible  to  transmit  the  keyboard signal back on the same coaxial
08500	cable as is used for the video.
08600	
08700		6. The video switch is a 32x64 electronic crossbar.  It  will
08800	be  a  copy  of  a  unit  now  in  use in the Artificial Intelligence
08900	Laboratory's display system.
09000	
09100		7. In the initial version of the system  all  characters  and
09200	vectors  are  produced by software in the mini-computer.  A PDP-11/45
09300	will take 150 microseconds in the worst case to  write  a  character.
09400	If  the host computers can support a higher rate of character writing
09500	then a special character writer can be added.
09600	
09700		Here are the components of  the  proposed  system  and  their
09800	estimated costs:
09500	
09600		1. Integrated circuit raster memory complete with
09700	buffer registers and power supplies				$73K
09800	(based on prices paid by Yale and quotes to M.I.T.
09900	
10000		2. Keyboards						$14K
10100	(70 keyboards at $200, based on quote by Microswitch)
10200	
10300		3. Monitors						$14K
10400	(70 monitors at $200, based on quote by Ball Bros.)
10500	
10600		4. PDP-11/40 with 16K words private memory		$20K
10700	(D.E.C. published prices)
10800	
10900		5. Shift registers and control electronics		 $5K
11000	
11100		6. Video switch						 $9K
11200	(cost of video switch built by AI Lab)
11300	
11400		7. Keyboard multiplexer					 $8K
11500	
11600		8. Connection to PDP-10					$15K
11700	
11800		9. Connection to the IBM 360/67				$10K
11900	(in addition $300 per month rental for IBM hardware is required)
12000	
12100		10. Contingencies					$10K
12200	
12300				TOTAL				       $178K
12400	
12500	
12600		Not included in these costs are engineering which we hope  to
12700	do  with volunteer labor and wiring costs.  The necessary programming
12800	will  also  be  done  within   the   Computer   Science   Department.
12900	Maintenance  of  the system should cost about $5000 per year counting
13000	student labor and parts costs.
13100	
13200		Perhaps $50K of the costs can be obtained from projects.  The
13300	AI  Laboratory  should  pay  for  its  connection and the cost of the
13400	terminals used by project members on campus.   With  NSF  not  giving
13500	facilities  grants  any  more,  the  outlook  from that source is not
13600	bright.  We believe that the University should pay the main  cost  as
13700	the  major  laboratory  instructional  and  research  facility of the
13800	Department.