80-Bus News

  

March-April 1983, Volume 2, Issue 2











Page 33 of 55











GRAPHPAC COMMAND MANUAL Page 9

SCREEN

Graphpac format: SCREEN CC,RR

Purpose:

To place the cursor at a specified screen co-ordinate ready for subsequent PRINT statements.

Remarks:

On a 25 line by 80 character display, CC is a column number 1-80, RR ia a row number 1-25. SCREEN 1,1 specifies the top left character on the screen and SCREEN 80,25 specifies the bottom right character.

BAR GRAPH STATEMENTS

Three commands have been included to allow the construction of vertical bar graphs.

VBAR (Vertical bar)

Graphpac format: VBAR CC,RR,N

Purpose: To display a solid vertical bar on the acreen.

Remarks:

The bar which is one character wide, is constructed from the bottom of the character box specified by the screen position CC,RR for a height of N pixels. CC and RR are screen co-ordinates as used by the SCREEN command.

VBARH (half tone vertical bar)

Graphpac format: VBARH CC,RR,N

Purpose: To display a shaded vertical bar on the screen.

Remarks: This command acts in a similar manner to VBAR above.

DOWN (vertical print command)

Graphpac format: DOWN CC,RR “ any ascii characters"

Purpose: To easily label graph Y axis or vertical bar charts.

Remarks: CC and RR are screen co-ordinates as used by SCREEN, VBAR and VBARH.

GRAPHPAC COMMAND MANUAL Page 10

PSI (Put Screen Image)

Mbaslink format: RESET:PSI "DRIVE: FILENAME": RESET

Purpose: To save the screen image on disk.

Remarks:

If Graphpac is running with Microsoft’s Mbasic under CP/M care must be taken to ensure that the correct directory information is sent to the disk, PSI should always be preceded and followed with a RESET statement. This will ensure that the latest directory information is written to disk before the screen image file is created and that Mbasic is aware of the file afterwards. The user should also be aware of the effect RESET has on any disk files in use by a BASIC program, consult the documentation which accompanied your BASIC interpreter.

If drive is not specified the currently logged-in drive will be used. If the filename is greater than eight characters only the first eight will be used. The filetype extension automatically supplied is .IMG (for image).

GSI

Graphpac format: RESET:GSI “DRIVE: FILENAME”

Purpose:

To display on the screen an image previously saved, using the PSI command.

Remarks:

Due to the way Mbasic handles the disk I/O it is neceasary to precede PSI with a RESET statement, otherwise rubbish may be displayed on the screen. It will be noticed, if the user experiments, that RESET is not always necessary, however, it is advised that the user conforma with this procedure The closing quotation mark should always be included even if GSI is the last command in a BASIC statement line.

NS (Normal Screen)

Graphpac format: NS

Purpose:

To re-configure the screen format for normal text. i.e. 25 lines of 80 characters.

Remarks:

This statement has been included to allow convenient switching to a normal screen format so that fast scrolling and a normal width display are available if required. On execution the screen will also be cleared.

GS (Graphics Screen)

Graphpac format: Gs

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Page 33 of 55