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1 : $**$ MARGIN=.6 RUNNING MTS GRAPHICS PROGRAMS ON THE IBM PC 1. Introduction This document describes how graphics programs (e.g. *PLOTSEE) that produce graphics on a TEKTRONIX 4010 series terminal may be run on an IBM PC with output on an attached graphics monitor. This is achieved by use of TEKTRONIX 4010 terminal emulation software (TEKEMUL) running on the PC. This program communicates with MTS and causes the TEKTRONIX ASCII codes from MTS to be interpreted and displayed on the monitor. Thus a user needs a graphics monitor in order to use the system. TEKEMUL is written in complied BASIC. The structured nature (as much as BASIC permits) of the program is intended to allow it to be adapted to other micro-computers in the future. 2. Using TEKEMUL to Output MTS Graphics on the PC Here we assume that the user has some familiarity with operating the IBM PC. The emulation program displays graphical information in the high resolution mode of the computer. Thus the IBM colour/graphics monitor card and a graphics monitor must be attached to the IBM PC in order that the facility can work as intended. Upon inserting the disk containing TEKEMUL into the disk drive one merely types in "TEKEMUL". This command loads and begins executing the emulator program. The program is of an interactive nature making it quite easy to use. The following describes the use of the TEKEMUL program: a) A general instruction menu is displayed. This explains some of the operational details on how the program is to be used. Pressing any key allows one to continue on. b) A communication set-up menu is then displayed. The default parameter values for baud rate, parity, data size, and number of stop bits is displayed in bold face. It is up to the user to ensure that the communication parameters are correct before continuing. For example, he should insure that the baud rate given to the program is the same as the baud rate of the line that communicates with MTS. Changing the communication parameters is a simple matter of entering the new value of the parameter in place of the old value. If all of the parameters are correct the user enters a "Y" to indicate that the parameters displayed are correct. The message "Time to flick your data set now..." is displayed momentarily and then the screen is cleared. It is at this point that the user initiates the connection with MTS. 1 c) The standard MTS header should be displayed at this time. When prompted for terminal-id, you should respond with "T4010". This signifies to MTS that you have a Tektronix 4010 series terminal. You can now sign onto MTS in the usual manner. d) TEKEMUL at this point in time is emulating a simple "dumb" terminal; it is not emulating the Tektronix 4010. Thus any attempt to run a graphics program will yield erroneous results. The Tektronix emulation phase is initiated by pressing F9 on the keyboard. e) Pressing F9 yields another menu which asks you what type of display monitor(s) you have. Enter "a", "b", or "c". And asks whether you want to use *IG or *PLOTSEE. Enter "c" or "d". And finally it prompts you f▀r the object module that will generate Ü the graphics. You may press the enter key if you are running *PLOTSEE. f) The program then switches to the color monitor (if you are not already on it) and issues the MTS RUN command in the form: $RUN -LOAD#+*IG or $RUN *PLOTSEE depending on which of the two facilities you selected. When your graphics program has completed running you will be returned to MTS. 3. Running More Than One Graphics Program Once you have been<eke> returned to MTS you can run another graphics program in one of two ways. You can (a) issue an MTS $RUN command directly or (b) press F9 once again. The MTS $RUN command will work directly since you previously pressed F9. Remember that F9 places you in Tektronix emulation mode and onto the color monitor. Thus any graphics codes intended for a Tektronix 4010 will be interpreted and executed by TEKEMUL. You may also press F9 again to continue having graphical programs run. 4. Exiting the Emulator and the Color Monitor Pressing F8 on the keyboard will transfer you back to the monochrome monitor ( if your system has one ). It will also take you out of Tektronix emulation mode but will leave you on MTS. 1 5. Exit to DOS Pressing the F10 function key will cause the program to transfer control back to the monochrome monitor ( if your system has one ) and will end the TEKEMUL program, leaving you back in DOS. It will not explictly sign you off MTS. You must either sign off yourself or disconnect the line. 6. System Overview TEKEMUL accepts Tektronix 4010 codes and plots the graphical information represented by these on the color monitor. Figure 1 illustrates how the system works. -------------------- | Graphics Program | MTS | | | | Tektronix 4010 | | codes | -------------------- | Communication line | ------------------------------ | TEKEMUL | | | | ----------- IBM | ---------------------- | | Color | PC | | | |----------| Monitor | | Communication Tektronix | ----------- | Program Code | | Interpreter | ------------------------------ Figure 1 - System Diagram To get MTS graphics on the PC color monitor, we have to have two programs running; one is the graphics program on the MTS side and the other is TEKEMUL in the PC. The latter allows the user to connect and sign on to MTS. At this stage no graphics is done yet and the PC simply acts as a regular terminal with the help of TEKEMUL. Once signed on the user can run the graphics program on MTS (such as *IG or *PLOTSEE) that generates the Tektronix 4010 codes. As MTS sends out the Tektronix 4010 codes, the emulator program on the IBM PC interprets the information and produces a picture on the monitor. 1 6.1 General System Information The information passed to the Tektronix emulation program is the same as that which would be passed to a Tektronix 4010 series terminal. Plotting of graphical information on the IBM PC is done in the high resolution mode of the BASIC compiler. Thus a color monitor hooked up to the IBM color monitor adapter must be used. The resolution of high resolution mode on the IBM PC is 640 horizontal pixels by 200 vertical. Thus TEKEMUL performs a mapping from the Tektronix coordinate space (1024 x 780) to the IBM PC coordinate space. 7. TEKEMUL Details The code for this program has been largely separated into subroutines and function key and communication trap routines. Figure 2 shows the program flow. Define and initialize global variables | Go to subroutine Set up screen border | Print out general instruction menu | Wait for keyboard input | Go to subroutine: clear out body of menu | Print out communication parameter menu | Set up communications. Initialize communications and F8 F9 and F10 trap routines. | | ------>-----------| | | | | | | ------<--------Keyboard input ? | | | No | Yes | | -------<------- Send input to MTS Figure 2 - TEKEMUL program flow 1 The program follows the sequence of events outlined in Figure 2. The last loop is one that the program constantly executes when it has nothing to do: reading input from the keyboard and if any input exists, transmitting it to the host. All other functions of the program are accomplished through trap (interrupt) routines. When a trap routine is finished executing, control is once again returned to the keyboard reading loop. 7.1 Subroutine and Trap Routines There are three trap routines in this program. One of them is for the communications buffer; the other three for function keys F8, F9 and F10. Any information received from the host causes an interrupt situation and control is passed to the communication trap routine. The structure diagram for this routine is in Figure 3. Communication YES ---------------> buffer empty? ----------------> Return | | | | | | NO | | | Get a character | | | Are we in Tektronix | emulation mode? | | | | | | | -----<---------------->------- | | | | | | | Go to Tektronix perform ordinary | simulation terminal functions based | subroutines on characters received | | | | ----->-----------------<------ | | | | -----------<------------ Figure 3 - Communication Trap Routine 1 The communication trap routine processes characters received from MTS one at a time until the IBM PC's communication buffer is empty. If the program is in Tektronix emulation mode then the character is passed to the subroutines that actually simulates the Tektronix 4010. If the program is not in Tektronix emulation mode then the character is merely printed on the screen. The routine then carries on to deal with the next character. The other three trap routines are executed depending on whether F8 F9 or F10 is pressed on the keyboard. The F8 trap routine allows the user to stay signed onto MTS, with the output of the screen going to the monochrome screen ( if one is attached ). The advantage is that most people prefer to use the monochrome monitor for viewing text as opposed to the colour monitor. The F9 trap routine begins the Tektronix emulation mode, switches the user to the color monitor and issues various instruction menus. Figure 4 shows the program flow for this routine. Set up instruction menu | Prompt for monitor types | | NO Does user have colour monitor -------->stop | YES | Prompt for graphics software to use (*IG or *PLOTSEE) | Prompt for user's object module | Switch to colour monitor | Enable Tektronix emulation mode | Send $RUN command to MTS | Return Figure 4 - F9 Trap Routine 1 The F10 trap routine ends Tektronix emulation mode and switches the user back to the monochrome monitor (if there is one). The diagram for this routine is in Figure 5. Disable Tektronix emulation mode | Switch to monochrome monitor if there is one | Exit to DOS Figure 5 - F10 Trap Routine The subroutines that actually simulate the Tektronix 4010 are comprised of TEKSIM, ESCAPE-TRUE and ESCAPE-FALSE. TEKSIM is called from the communications trap routine. Here the current character from the communications buffer is placed in BYTE as an ASCII decimal value. If the previous charactor was an escape character ESCAPE-TRUE is called; else, ESCAPE-FALSE is called. ESCAPE-TRUE simulates the various functions of the escape sequences for the Tektronix 4010. ESCAPE-FALSE checks to see if the current character is a control character or not. If it is a control character then the appropriate control function for the Tektronix 4010 is simulated. Characters other than control characters are decoded into X,Y coordinates. When a complete (X,Y) address is decoded then a move or a draw is made to that coordinate address. A draw is accomplished by using the BASIC subroutine LINE to draw a line on the screen. 7.2 Global Variables Global variables important to the simulation part of the program are described below. TEKAMUL: a flag indicating whether the program is in Tektronix emulation mode (TEKEMUL=1) or isn't (TEKEMUL=0). MODE: indicates if we are in graph mode (MODE=0) or alpha mode (MODE=1) of the Tektronix 4010 terminal. DARK: this flag, when set to TRUE, indicates that the next vector drawn is to be a dark vector. DARK is set to TRUE when a GS control character is encountered. 1 7.3 Adaptability to other Micros TEKEMUL has been structured so that it may easily be adapted to other micro computers. Should the communications facility on another micro be different than the IBM PC's then one can merely use the simulator routines TEKSIM, ESCAPE-TRUE, and ESCAPE-FALSE from the TEKEMUL program. All that these routines require to function by themselves are the global variables defined in the start of the program and a character given to the subroutine TEKSIM. 8. History of the Emulator Program The original Tektronix emulation project began with a desire to preview an MTS graphic Plot Description File (PDF) on the IBM PC. We decided to write a program for the IBM PC which would be much like *PLOTSEE on MTS, except it would run in the PC. However, we encountered some practical problems with this scheme. The most serious of these problems was the amount of time required to plot a PDF. This time factor was due to the fact that the PDF had to be transferred over to the IBM PC in order to be plotted. A PDF can be on the order of 800,000 bytes. Given this size it was calculated that many plot files would require several minutes to be transferred using the file transfer programs. Another problem complicating the design approach was that Plot description files are in binary format. The file transfer programs transfer binary information much slower than character information. One solution to this was to represent vector coordinates in a more compact form. This solution led to the Tektronix 4010 method of transferring coordinates as efficiently as possible. We considered converting a plot description file's vector coordinates into Tektronix format vector coordinates. This much smaller file could then be transferred over to the IBM PC (as character data) and then plotted. But there was no sense writing a conversion program to translate a PDF into Tektronix format vector coordinates since Integrated Graphics already has a device driver for the Tektronix 4010 that generated what was needed. It was desirable to eliminate the file transfer step and have the Tektronix emulator work in real time as MTS delivered Tektronix 4010 graphics commands. The regular Tektronix 4010 device driver can be used on MTS, and, it would be easy for the user to operate. In fact the IBM PC would operate just like a Tektronix 4010 from a logical point of view. 1 to operate. In fact the IBM PC would operate just like a Tektronix 4010 from a logical point