The Tektronix 4010 Vector Graphics Terminal.

This amazing machine was built in the early 1970s.  It can be used as a video terminal for text information, or as a vector graphics workstation.  The display is a storage type cathode ray tube.  If the image is displayed with high intensity, then it will persist until the screen is cleared.

Here it is shown displaying the time (it's almost 3:00), using a QBASIC program Steve and I wrote, running on a Zenith Supersport 286 laptop.  The program draws a new minute hand and a new hour hand at the top of each minute.  It erases the screen at the top of each hour.  This is done through the serial port, at 2400 bps. (please excuse the sloppy programming!)

The display has 1024x768 addressable locations in graphics mode.  The storage screen acts as the video memory, so there is no way to change what is already being displayed without a complete screen erase.  In text mode, only upper case letters are used (the character set is limited to 96 characters).

There is a bit of information on the web about the graphics encoding scheme, as these terminals were emulated for years after they became obsolete...replaced by less expensive raster displays with digital video memory.

This is what's inside the pedestal.  The huge linear power supply at the bottom supplys a lot of 5 vdc for the many TTL chips, as well as higher voltages for the defelction amp and crt circuitry.  The relay is for local/line switching, and the TTY/RS-232 interface connector is hidden behind it.  The righmost card in the cage is the TTY interface, and has lots of jumpers and some pots to adjust.  To get it working as RS-232-C at 2400 bps, n,8,1 parity/bits/stop bit, I set the T Data strap to Normal, R Data strap to Invert, Baud Shift to On, and adjusted the trimmer by TP1 to give a clock frequency of about 19 kHz, measured at TP1.  It appears that the data rate is 1/8 of the clock frequency.  There is a clock multiplier jumper, but it seems to have no effect on operation...in fact, none of the other jumpers seem to make any difference in how it works (except for echo, which is self-explanatory).

I have learned from a helpful person on the comp.terminals newsgoup that the TTY interface option originally would have come with an I/O card to be installed in the computer that the 4010 was used with.  There was another interface option available, which provided a "proper" RS-232C connection.

The circuit boards are wild...the TTY board is 6 layers, and all the traces are gold plated.  It is copyright 1971 by Tektronix.  Quite impressive technology for the time!

This little sticker is inside the bottom cover, and did provide some clues to getting the comm working.  It also suggests that this terminal was used with a Nova minicomputer at some time in it's life.  There is also a University of Arizona property tag on the terminal, which seems to be common on old computer gear in southern Arizona.
 
 NOTE:  I no longer own this terminal, someone at a big company needed one to keep a system running, found this web page, and bought the 4010 from me.