A.1 Valid Control Sequence of VT 

VT.EXE  supports  part of VT52  control sequence which are list in the following. 

1. Cursor up                                              code= ESC A

      Move  the  active position  upward  one position.

2. Cursor down                                          code= ESC B

      Move  the active position downward  one position.

3. Cursor right                                            code= ESC C

      Move the active position to the right.

4. Cursor left                                              code= ESC D

      Move the active position to the left.

5. Cursor to home                                       code= ESC H

      Move the cursor to the home position.

6. Reverse line feed                                     code= ESC I

Move  the  active position  upward  one position   without   altering   the    column position.  If  the active position is at  the top margin, a scroll down is performed.

7. Erase to end of screen                             code= ESC J

      Erase  all  characters from the  active position to the end of

      screen.

8. Erase to end of line                                  code= ESC K

Erase  all characters from  the  active position to the end of the current line.

9. Direct cursor address  code= ESC Y lin col

Move  the cursor to the specified  line (lin) and column (col). 

A.2 Extended Graphics Capability 

VT.EXE    provides   extended   graphics capability  which  may accept a  sequence  of graphics  control code (which is  represented by  ASCII  code)  to  draw  a  line,  circle, ellipse ...  etc. on the display monitor. The graphics  functions  can be used  under  EGA, VGA,   hercules,  and  8514  modes  or  other display   mode  that  supported  by  turbo  C graphics tools. The control sequence of these graphics   primitives   are   list   in   the following. 

1. Enter graphics mode 

  code= ESC P    

When  VT.EXE  accepts ESC  P,  then  the terminal  evaluator enter to graphics mode to ready accept graphics operation commands. The resolution of graphics mode depend on your PC monitor and adapter type which is detected by VT.EXE automatically. 

2. Exit from graphics mode to text mode 

  code= Q 

When  terminal evaluator is at  graphics mode, it can accept Q to enter text mode.

3. Move cursor to X,Y position 

  code= Mxxxxxyyyyy 

 Move  to (xxxxx,yyyyy)  position.  Where xxxxx represents  X coordinate,  which length is   five   digit.    yyyyy   represents    Y coordinate, which length is five digit. 

4. Draw to X,Y position 

             code= Dxxxxxyyyyy 

From    current   position    draw    to (xxxxx,yyyyy) position. 

5. Draw a line 

  code= Lxxxxxyyyyywwwwwzzzzz 

     Draw   a  line  from  (xxxxx,yyyyy)   to (wwwww,zzzzz). 

6. Draw a circle 

  code= Cxxxxxyyyyyrrrrr 

Draw    a   circle   whose   center   is (xxxxx,yyyyy) and its radius is rrrrr. 

7. Draw ellipse  

             code= Exxxxxyyyyyrrrrrsssss

Draw   a  ellipse  whose  center is   at (xxxxx,yyyyy),  and  the length of semi-major axis is rrrrr,  the length of semi-minor axis is sssss. 

8. Draw a point 

  code= Pxxxxxyyyyy

     Draw a point at (xxxxx,yyyyy). 

9. Write a string 

            code= Sccccc<CR>

Draw  a graphics string on  the  screen, the string are quoted between S and <CR>. The maximum string length is 80 characters. 

10. Select one color attribute 

   code= Axxxxx

Select  pen color,  the color number  is specified  by  xxxxx,  where xxxxx  has  five digit length.

We   will  give  some  example  to  show graphics ability in the section A.4. 

A.3 How to Execute VT.EXE 

After   PCCOM.SYS   is   executed   (For example,  set  up 3F8 port), just run  VT  to enter  virtual terminal evaluation mode.  The screen you will see is shown below.

You  may key in character from  keyboard to  communicate with host computer or  select function  to setup communication  parameters. All available function keys are shown in  the following. 

F1   HELP

When press F1 key,  system will display functions that you can select. 

F2   S/CTRL  

Press  F2  key will send XOFF  code  to host computer to notice that virtual terminal is  too busy.  When you want set XON to  host computer again, please press Q/CTRL. 

F3   SETUP

Setup the communication protocol such as baud rate, data bits, stop bits ... etc. 

F4   C/CTRL

Press  F4  key  will send C/CTRL code to remote   computer  to  kill   the   executing process.

F5   LISTCFG

     List the communication parameters on the screen. 

F6   SAVECFG

Save  the setup communication parameters to disk file named VT.CFG. 

F7   Download (receive data from host)

Receive  data from the remote site  then save these data to a user specified file. 

F8   Upload (transmit data to remote site)

Transfer  a  user  specified  file  that located at PC (which is now run VT) to remote site. 

F9   EXIT

     Exit virtual terminal evaluator. 

F10  SHELL

Fork  MS/DOS shell command  interpreter, the  terminal evaluator is still resident  on the   main  memory.   When  you  enter  shell command,  you may run any MS/DOS commands and programs, because you stay at MS/DOS mode. To enter VT again, please type EXIT. 

A.3.1 Download Data from Host 

When  you select F7,  system will ask  a file  name  which is used to save  data  that sent from remote computer. 

Suppose   your   virtual   terminal   is connected  to XENIX operating system and  you want download a file aa from host to PC,  and

save it in PC.DOC file, the procedure is 

A.3.2 Upload Data to Host 

When  you select F8,  system will ask  a file name and send the file contents to  host computer.   Under   XENIX  operating  system, suppose  you want send a file PC.DOC from  PC to host computer and save it in aa file,  the upload procedure is 

A.3.3 Setup 

When you select F3,  you may modify  the communication parameters. After communication parameters are setup,  you may use F6 to save the   configuration   and  F5  to  list   the configuration.  When  VT is loaded,  it  will check   VT.CFG   to load the last save configuration automatically. The communication  parameters  are  list  in  the following. 

1. port number

     Select which I/O port.

2. baud rate

     Select communication speed.

3. data bits

    Select data bits

4. stop bits

     Select stop bits.

5. parity

     Press SPACE bar to select parity.

6. ECHO

Press  SPACE  bar to select  local  ECHO ON/OFF.   When   your   host   computer   has ability   to   send   back    the    received character,  you must select local ECHO OFF to let   host   computer  prompt   your   typing character.

7. new line

Press  SPACE  bar  to  select  new  line ON/OFF. VT will add <CR> code when it receive <LF> at new line ON mode.

8. delay time

Select  delay time interval between  two transmitting   characters  when   upload   is processing. 

A.4 Examples 

The following control string will draw a figure which is shown in the next page. Don't forget to press any key to enter text mode. 

Where  <ESC> is an ASCII code of  <ESC>. We have not store <ESC>P to the VT.DOC  file, so  that  you must send it from  keyboard  to enter graphics mode.