Contents:

VT100 Video Terminal

Technical Manual EK-VT100-TM-002

This was one of the most common video terminals used with the PDP-11 series. The VT52 was an earlier model, which had a slightly different set of control codes. The VT100 can emulate a VT52 if desired. The VT2xx and VT3xx models followed the VT100 and typically performed supersets of its command sequence (ie weird color stuff). The VT100 is a black and white monitor which communicates with a host computer or modem via an RS-232 serial link or optionally a 20 ma current loop. One of the things that makes it interesting is that it was expandable via various option cards. As a point of interest, the original Decmate systems were VT100 terminals with a Harris option card which emulated a PDP8. I strongly recommend vt100.net for more detailed information on the VT100 series.

Setup mode is entered by pressing the SETUP key. One starts in setup mode A, you toggle between modes A and B with the '5' key. The top row of keys has labels describing their setup functions. The table below indicates the features you can change:

Feature                Key(s) to toggle
           Setup Mode A
Brightness             up and down arrow
Characters per line    '9' if AVO present
Line/Local             '4'
Tabs                   '2' and '3'  after set cursor at position
           Setup Mode B
Answer back            'Shift' & 'A'  see comment below
ANSI/VT52 mode         '6'   0 - VT52  1 - ANSI
Auto Repeat            '6'   0 - off   1 - on
Xon/Xoff               '6'   0 - off   1 - on
Bits per char          '6'   0 - 7     1 - 8
Cursor                 '6'   0 - underline 1 - block
Interlace              '6'   0 - off   1 - on
Keyclick               '6'   0 - off   1 - on
Margin Bell            '6'   0 - off   1 - on
New Line               '6'   0 - off   1 - on
Parity                 '6'   0 - off   1 - on
Parity Sense           '6'   0 - odd   1 - even
Power                  '6'   0 - 60hz  1 - 50hz
Receive Speed          '8'   steps through range
Screen                 '6'   0 - dark  1 - light background
Scroll                 '6'   0 - jump  1 - smooth
Transmit Speed         '7'   steps through range
Wraparound             '6'   0 - off   1 - on
US or Brit # sign      '6'   0 - US    1 - Brit

                 - margin bell               -  parity sense
                 | - keyclick                | - parity
                 | | - ansi/vt52             | | - bits per char         
                 | | | - xon/xoff            | | | - power
   _ _ _ _       _ _ _ _       _ _ _ _       _ _ _ _
1 |_|_|_|_|   2 |_|_|_|_|   3 |_|_|_|_|   4 |_|_|_|_|
   | | | |                     | | | |
   | | | - scroll              | | | - interlace
   | | - autorepeat            | | - new line
   | - screen                  | - wrap around
   - cursor                    - # sign

Note the transmit and recieve speeds can be set independantly when in setup B with the '7' and '8' keys, the result is displayed to the right of the option boxes shown above. Most setup B options are toggled with the '6' key. First one places the cursor on the appropriate box above using the left and right arrow keys, the toggle option with '6' key. If you are really lucky there is a big label on the bottom of the keyboard detailing all this, but a lot of people never stuck them on!

There are a set of ansi escape sequences that a host computer can send to temporarily modify a terminals characteristics, or ask the terminal its current configuration. One such sequence asks the terminal for an answer back string of up to 20 characters. You can set this string from Setup B by pressing 'Shift' and 'A' at the same time. The terminal responds with "A=" on screen. You type any character which you don't want in your string as a delimiter, then type your string and press the delimiter character again to terminate the string.

You can save your current selections by pressing 'SHIFT' and 'S', the terminal responds with "wait" while it stores settings in NVR. If you want to cancel some entries you have made temporarily, press 'SHIFT' and 'R' to recall what was saved last in the NVR. Changes made in Setup or via escape sequences from the host are temporary until a reset or power off/on sequence unless saved per above.

The back side of the terminal has the power cord and switch on one side and the i/o ports on the other. The keyboard plugs in with what looks like an old microphone jack. There is at least one male db25 RS-232 connector (some of the other options have more). The rectangular piece of the back panel which covers the keyboard and RS-232 connector(s) can be removed with 4 screws. It may contain a current loop option which plugs into the terminal controller module, J5.

The terminal controller module is a large (10" x 10") circuit board. In a bare bones VT100 its the only circuit board. There were at least two styles. The older one connected to a set of pins from the power supply that plugged into the middle of the board from the side. You removed some clips, and slowly wiggled the board loose. This isn't even described in my reference. The newer style has a edge card connector, J6, on the back which the power supply harness connects to as shown below. The power harness may connect directly to the board, or there may be a small expansion backplane that allows additional boards access to the power supply (as in VT103, VT125, and VT180).

   ___________________________________________________  
   |                                             _   |  
   |    - - - - - - - - - -                     |J|  |  
   |   |               | J |                    |2|  |  
   |                   | 1                      |_|  |  
   |   |               |   |                         |  
   |                   | A                           |  
   |   |               | V |                     J5  |  
   |                   | O       J3 STP              |  
   |_  | - - - - - - - - - |    ____________         |  
    _|                                               |  
   |                                                 | | 
   |                                                 | | J4 EIA 
  J|                                                 | |  DB25
  6|                                                 |  
   |                                                 |- J8 Video in  
   |_                                                |- J9 Video out  
    _|                                               -  Keyboard
   |_________________________________________________|


The video in and out are BNC connectors. J2 is the multi pin (18?) graphics connector used with some options (I've never seen one in use). J5 is the 20ma current loop connector. J3 is the STP connector discussed below. J1 is a row of pins which is always present. If there is an Advanced Video Option (AVO), it piggy backs on the board in the location shown and mates with the J1 connector. The AVO adds some memory which allows a 132 column display in addition to the normal 80 columns. I think it adds some graphics characters also.

At power up, a VT100 does a fairly extensive self test. Leds on keyboard should flash and it should beep at you. If all is well the cursor will be displayed. If you get a character and it goes to "offline" mode the self test detected an error. There is a list of about 30 errors, but I'm getting tired and not sure how much it would help you. Lets hope its ok. Many errors aren't fatal, try it on line and see what it does!

VT102 Video Terminal with Printer Port

User Guide EK-VT102-UG-003

This has all the video capability of the VT100 with the addition of the printer port, however lacks an STP slot for option modules. It uses a different terminal controller module which allows one to setup the printer port characteristics as well as the modem (normal EIA port). The additional printer port is located above the modem port. The modem port is in the same location as it is on a VT100.

In setup mode B, one switches between the modem and printer port characteristics by pressing 'Shift' -> and 'Shift' <-. The left and right arrow keys while pressing the Shift key.

Standard Terminal Port (STP) Connector

There is a shorting connector located as shown above on most of the VT100 terminal controller modules. I give it a separate section as the "paddle board" modules that plug into this connector provide the interface to transform the base VT100 into various other systems. When no STP module is installed, the EIA connector (male db25) on the back of the terminal acts as the serial i/o port. When installed, the STP module normally re-routes this i/o port to connectors on the module. Various STP modules I have seen are described in the sections below. If in doubt you can often check out the functionality with an ohm meter given the STP edge card connector layout below.

The connector consists of twenty pairs of contacts. The even numbered contacts connect (short to) the odd number in the pair when no module is installed. I don't fully comprehend the table below, but its what the manual says. The even numbered pins are signals from the terminal controller board, odd number pins with an '*' are connected to J4 pins as indicated.

VT100                STP                       J4 Pin
TXD                 2   1*   Line TXD            2
 -                  4   3    Ext TCLK 
RXD                 6   5*   Line RXD            3
RTS                 8   7*   Line RTS            4
 -                 10   9    Ext RCLK
CTS                12  11*   Line CTS            5
DSR                14  13*   Line DSR            6
DTR                16  15*   Line DTR           20
CD                 18  17*   Line CD             8
RI                 20  19*   Line RI            22
SPDS               22  21    Line SPDS
SPDI               24  23*   Line SPDI          12
-12V               26  25    --
TCLK               28  27    Internal TCLK
RCLK               30  29    Internal RCLK
+12V               32  31    --
Option Present     34  33    Signal Gnd
Local CLK          36  35    --
Init               38  37    --
+5V                40  39    --
Controller       Connector
  Board

On the VT103 and VT180 the paddle board has connectors that send the terminal controller signals to the console port of the extra processor installed in the system and use the J4 port as an extra SLU input for this processor. The images below of the VT103 paddle board show that the even number pins, 2-38 are on side 1 of the paddle board and exposed when the board is inserted in the terminal controller STP slot. The odd number pins, 1-37, face the componet side of the terminal controller when the paddle board is inserted in the STP slot. Note the VT103 and VT180 paddle boards are the only ones I've seen, neither uses STP pins 39 or 40.

VT103 LSI-11 Video Terminal

User's Guide EK-VT103-UG-001

The VT103 is a VT100 case and display with an LSI-11 backplane option. The VT103-BA option included a dual TU58 DECtape II installed in the bottom of the VT100.

To support the LSI-11 backplane an H7835 power supply was added (this is an upgrade of standard power supply). Technically the backplane is two H803 (2x4) connector blocks combined to create a 4x4 backplane configuration. It conforms to all backplane configuration rules for 25 cm (10 in) length backplanes per Microcomputer Processors handbook. The is also a fan assembly above the backplane to facilitate cooling.

I include scans of both sides of the VT103 paddle board that is in my VT103 system: Side 1 and Side 2.

                                     1  2  3  4
              -------------------------------------
              |+12 +5                             |
              | ||| ||               |  |  |  |   |
          J3->| ------               |  |  |  |   |
              | ||| ||               |  |  |  |   |
              |   G  G               |  |  |  |   | D
              |   n  n               |  |  |  |   |
              |   d  d               |  |  |  |   | 
              |                      |  |  |  |   |
              |                                   |
              |                      |  |  |  |   |
              |                      |  |  |  |   |
              |                      |  |  |  |   |
     B        |                      |  |  |  |   | C
     a        |                      |  |  |  |   |
     t        |                      |  |  |  |   |
     t  +5  ->| x                    |  |  |  |   |
     e  gnd ->| x                                 |
     r  +12 ->| x                    |  |  |  |   |
     y        |_                     |  |  |  |   |
               _|                    |  |  |  |   |
     E        |   | o-w4-o           |  |  |  |   | B
     d  P     |   | o-W3-o           |  |  |  |   |
     g  o     |   | o-W2-o           |  |  |  |   |
     e  w     |   | o-W1-o           |  |  |  |   |
        e     |   |  |                            |
     C  r     |   |  |               |  |  |  |   |
     o        |   |  |               |  |  |  |   |
     n  H     |   |  |               |  |  |  |   |
     n  a     |   |  |               |  |  |  |   | A
     e  r     |   |  |               |  |  |  |   |
     c  n     |_  | J2               |  |  |  |   |         
     t  e      _|J1 o-W5-o           |  |  |  |   |
     o  s     |                                   |
     r  s      -----------------------------------

   J3 is the 6 pin connector for TU58 tape drive, +12v to left,
   two grounds, and +5v are active.  The pin between +12v and 1st Gnd
   is labled N/C (not used?).

   Normally battery backup is not used.  The Edge connector shown above
   goes to the H7835 power supply.

   J1 is for the 22 pin terminal controller module (VT100 std)
   J2 is for 18 pin graphics module.

   Jumpers W1 to W5:
   W4 - enables line clock (LTC) interrupts, not factory installed
   The rest should not be changed from factory configuration:
   W1,W2,W5 - installed  W3 - removed

   If you lay the backplane on its side, its easiest to see the
   option order (highest = 1, lowest = 9):
                       slot
   row     A         B          C           D
    1        1 (CPU)                  2
    2          4                      3
    3          5                      6
    4          8                      7


    Typical option configurations shown in my manual are:
    A: 1 CPU, 2 MSV11-DD (memory), 3 DLV11-J (4 line i/o)
    B: 1 CPU, 2 MSV11-A (memory and serial i/o)

    The standard VT103 has an STP Module as shown below:

        B              ---------------------------
        a             |    \_               _/    |
        c             |  J1 _|             |      |
        k             |    /               |      |
    <-                |                    | J3   |     
        P             |    \_              |      |
        l             |  J2 _|             |_     |
        a             |    /                 \    |
        n             |_                      ____|
        e               |____________________|

                         Edge Connector to STP

   J1 and J2 are 10 pin connectors, J3 has 40 pins
   J1 is the consol connector
   J2 and J3 are for a second serial line unit, SLU.
      Both connect to the external EIA connector on the
      rear of the terminal via the STP connector on the
      paddle board, use J2 or J3 (not both) depending
      on the connector type of your 2nd SLU.

 My VT103 had a DEC ribbon cable connection J1 to an M8186 CPU.
 DEC part ##91-07747-02
 The red tracer was on the bottom, and the index slot, pin 6, for
 the blanking plug is next to the circuit board so pin 1 is on
 the bottom of J1 and J2 furthest from the circuit board (see DLV11 pinout).
 See the DL11 documentation for the M7800, EK-DL11-TM-001, for J3 pinout.
 Comparing J2 and J3 function, it is clear J3 pins AA - UU are those
 closest to the circuit board with AA at the bottom as viewed above.

 The paddle board just consists of the three connectors above and the
 traces to make them active.  W1 on side 1 indicates two solder points 
 that would join STP:38 and J1:1 if connected with a jumper.
 This jumper is not installed on my board.

 I observe the following connection on my VT103 Paddle Board:
 STP pins 36,29,27 all tied together and to J1:10
 GND connected to following pins and J1 and J2: 2,4,5,7,9
                  following pins on J3: A, B, UU, VV, HH

 The STP contacts connect directly to the following pins:
 STP   J1   J2   J3
  1         8     F
  2     3
  3               N
  5         3     J
  6     8
  7               V
  9               R
 11               T
 13               Z
 15               DD 
 17               JJ
 28               CC  
 29    10
 33     2   2     A,B,UU,VV   (GND see notes above)


 The standard VT103 STP board sends an external clock from the
 VT103 setup to consol ribbon cable, J1.  You need to look closely at
 the VT103 manual to see you can't pre-define the consol baud rate
 with a wirewrap if connecting to J1 on the STP.  I was testing
 the other day with a MXV11 which worked fine in another box.
 When installed in the VT103, it gave a loud repeating "dash" 
 sound from keyboard speaker when powered up.  Removing the
 consol baud rate wirewrap on the MXV11 solved the problem 
 allowing the VT103 setup option to control baud rate.


 The H7834 Power supply provides the following currents, you
 must subtract off the Monitor and TU58 options installed
 to determine what is available for componets.
 Voltage Current Monitor Basic Video Adv Video TU58
  +5V     16.0A     0       2.5A       1.1A    0.75A
 +12V      5.0A    1.0A     0.6A        0      0.6A *
 -12V      0.5A
 -23V      0.01A

 * TU58 draws +12V and 1.0A as a spike on tape startup
 Power supply voltage switch selectable 90-130 or 180-250 Vac
 The supply monitors two power levels and sets backplane
 signals accordingly:
 BPOK H  - ac power ok (negation warns of impending loss of power)
 PDCOK H - dc power ok (   "      "         "        "      "    )
 

VT180 CP/M Personal Office Computer

This was my first computer. I'm very fond of it. It is a VT100 with an additional board which contains a Z80 CPU and a floppy disk controller. One can connect four single sided 180 kb floppy disks to this configuration. It has 64 kb of memory and runs a version of CP/M. I was ever so excited when I upgraded from my 300 baud modem to a 1200 baud unit! Its been almost 10 years since I turned one on, but I still have several in the basement and pat them when I walk by.

I also wrote some of my first software for this. A *.asm xmodem program, I forget quite why probably cause my local BBS required it rather than Kermit and I couldn't find an xmodem for the VT180. Later I wrote some routines that would copy the single sided VT180 disks to a PC using the PC's 5.25" drive as I migrated my work to the PC. Doubt anyone needs this, but its available if of any use. The VT180 is not only obsolete, but a pretty rare animal so I won't give a lot of detail although I do have some experience if I can just remember it!

VT180 Series Technical Manual EK-VT18X-TM-001
I own this manual, and recently scaned it. I hope to get the resulting 14Mb vt180tm.pdf onto vt100.net and bitsavers.org who have more bandwidth than I. In the meantime I'm putting some of the key chapters up on this page as individual PDF segments in case you need some of it:

Chapters 2, 5 and the Appendice are very similar to other VT1xx setup and installation info, and Chapter 4 on generic CPM operation can be found elsewhere on the web.

An expansion backplane was included so the power supply cable connects to an edge connector giving both the terminal control module and the new VT18x board access to power. They plug in side by side in the VT100 case. Looking at the back side of the terminal case, the external connectors are as follows:

              Back View of VT180
         -----------------------------------------------
        |                                              |
        |     |P                                       |
        |     |R                                       |
        |     |T   |D                                  |
        |          |I                                  |
        |          |S                                  |
        |          |K                                  |
        |                                              |
        |                                              |
        |                                              |
        |     | G                                      |
        |     | P  |C                                  |
        |     |    |O                           On     |
        |          |M                   Fuse     o     |
        |                                       Off    |
        |    VI                                Power   |
        |    VO                                |   |   |
        |    KB                                  |     |
        |                                              |
        ------------------------------------------------


               Componet View of VT18x Module
        ------------------------------------------------
        |                                          1 o | L
        |                                          2 o | e
        |                                          3 o | d
        |                                          4 o | s
        |                                              |
        |                                              | | D
        |                                              | | I
        |                                              | | S
        |                                              | | K
        |                                          _   |
        |                                         |J|  |
        |                                         |3|  |
        |                                         |_|  |
        |                                              | |C
        |                                          _   | |O
        |  R   R                                  | |  | |M
        |  O   O                                  |S|  |
        |  M   M                                  |1|  |
        |  1   2                                  |_|  |
        ------------------------------------------------


        pinout for VT18x J3 and Paddle Board J2
        pin 1 is upper left when viewed as one inserts cable on componet side

                    fig 6-28  matches layout below
        red tracer-> 1  16 
                     2  15
                     3  14
                     4  13
                     5  12
                     6  11
                     7  10
                     8   9     [note pin 8 not used on paddle board]

        The ribbon cable connects like # pins on the J3 and J2 sockets
        on the VT18x module and Paddle Board.

VI - video in
VO - video out
KB - keyboard
The system connects the VT18x module to the terminal controller module via the custom paddle board above which is inserted in the STP connector. The paddle board has a 16 pin socket,J2, which connects to J3 on the VT18x module via a ribbon cable supplied with the system (red trace at top on both connectors). Table 6-35 pp 6-100 shows the signals carried on this cable and Figure 6-28 pp 6-66 diagrams how the VT-18x control module connects to the terminal controller module through the paddle board. Figure 6-28 maps to my diagram above as follows: PRT => J1 on Paddle board, GP => J4 on terminal controller, COMM => J1 on VT18x module. The STP connector includes the Printer port DB25 connector (PRT above) and converts the standard VT100 EIA (DB25) connector to a general purpose (GP) serial port. Both ports are now controlled by uarts on the VT18x module. The VT18x module also contains the 37 pin disk drive connector port (DISK) and a second serial communications port (COM). All three serial ports are male db25 connectors.

The VT18x dip switch, S1, is factory configured as follows to control the COM port shown above:

                             VT180
Switch  Setting  NAME        Source    COM Pin
1       on       RTS         from         4
2       on       CTS         to           5
3       off      SCTS        to          13
4       on       SI          to          12
5       on       SRTS        from        11
6       on       TXD         from         2
7       off      STXD        from        14
8       on       SRTS        from        19
9              (no used)
10      off      SPDS        from        23
When the system boots it does a self test and then you get a menu that prompts for an operating mode. You can boot off floppy disks A-D (it always offers this even if they aren't installed), run the self test, or run in terminal mode. In terminal mode the COM port passes RS-232 data directly to the terminal controller module as if it were a VT100 (note COM is not the normal i/o port for a VT100). The COM port parameters are derived from the SETUP B terminal controller module settings. The PRT and GP ports are controlled via CP/M.

This system can control up to four disk drives. The drives were sold in dual drive units. Mine came with Shugart Model # 400L drives for A & B and Teac FD-50A-03-U drives for C & D. There are some internal dip switches and a terminating resistor pack is required on drive A. My manual shows the terminating resistor pack location just to the left of the dip switch on each drive (unless drive A this socket should be empty). The settings for these dip switches control how the drive responds as follows:

   switch is on to left viewed from top and off to right
Switch                Drive 
           A   B   C   D
 8        off off off off
 7        off off off off
 6        off off off on 
 5        off off off off
 4        off off on  off
 3        off on  off off
 2        on  off off off
 1        on  on  on  on
The table above works for the Shugart Model 400L, but the Teac drives only had 6 dip switches, and switch # 5 was always on as well as the ones shown above.

As shipped the system only wrote single sided disks, but the controller has the capability to talk to double sided drives. Fifteen years ago when this was a hot topic on Compuserve, there was information on how to make the disk controller work with other disks, including 700kb 3.5" disks. I have some of this information, but never tried it, seemed like it was easier to get a newer computer that already knew what a 3.5" disk really was! Besides, I seem to remember you had to soil your hands with a soldering iron and make patches in the CPM bios.

I was contacted in 2006 by Dave who had obtained a VT18x module and disk drive, but no paddle board, disk drive cable, nor terminating resistor. His questions goaded me into scanning the technical manual, but we found there still appeared to be some unanswered questions. I spent a couple days measuring resistances and looking at the paddle board on my system to see if I could figure out how to generate the missing componets or at least generate a work around solution. For the historical record I include scans of both sides of the VT180 paddle board: side 1 and side 2. Take the following observations with a grain of salt, but its the best I can come up with and my paddle board does appear to match the technical manual description!

As previously mention, Figure 6-28 pp 6-66 of the Technical manual includes a skematic of the paddle board. To the best of my knowledge the pinouts for the IC sockets, J2 and J3, for the ribbon cable between the VT18x and paddle board shown above matches this skematic although I see no mention of the pinout in the manual. Matching the socket locations for the J1:# printer port pins confirms this numbering as does the fact that J2 locations 5 and 13 are clearly tied to ground, and location 8 connects to nothing.

The technical manual does mention that the paddle board contains filtering elements for the printer port, J1. These are partially indicated by the inductances L1 - L5 shown in figure 6-28, and seen as five black cylinders in the center of side 1 of the paddle board scan. I'm told these have a ferrite core to limit propagation of high frequency noise on long serial lines. Although not shown in figure 6-28 there is what I'm told is probably a 100 pico farad capacitor connecting the side of the inductor furthest from J1 to ground for J1 pins 2,3,6, and 20. You can just see these next to the inductors in the scan of side 1. There are also a couple resistors as shown in figure 6-28 which are tied to the +12v supply from the terminal controller to provide control signals for the printer and general purpose ports.

Table 6-12 pp 6-67 lists the signals carried by the disk drive cable.
Looking at the male ends on this cable one sees numbers:
     DB37 to VT18x module        DB25 on drive enclosures
  --------------------------      ---------------------
  \  1       ....      19  /      \  1    ...     13  /
   \ 20                37 /        \ 14   ...     25 /
    \--------------------/          \---------------/


I only show existing pins below, many slots were blank on both
ie db37: 1-5, 7,11,13,15,17,   |  db25  14,17-19
         29,32,33,35-37        |

                db37  db25
                6       1
                8	      2
                9      15
                10      3
                12      4
                14      5
                16      6
                18      7
                19     20
                20      8
                21     21
                22      9
                23     22
                24     10
                25     23
                26     11
                27     24
                28     12
                30     25
                31     13
                34     16

I examined one terminating resistor pack on my A-B drive pair. It appears to have two part numbers on it: CTS7420 and 60-3-R150. Note the R150 is followed by an ohms sign which I can't reproduce. The pack is an IC with two rows of 8 pins each. One measures a resistance of 150 ohms between opposite pins, ie if pin 1 is the upper left and pin 16 is the lower right I measure 150 ohms between each odd numbered pin and the next higher even number such as 1 to 2 and 15 to 16.