Tabcalc

TABCALC


by J.F. Tydeman


from ZX Computing Feb/Mar.1986





An excellent spreadsheet program from J.F. Tydeman,


specifically for the Wafadrive and Kempston E, but


very easily modified to suit all systems.








TABCALC is a spreadsheet program designed to take full


advantage of the facilities offered by the Rotronics


Wafadrive and a line printer. An alternative listing is


provided to permit the program to be used with the Kempston


'E' interface and a little hacking is all that is required


to adapt the program to other interfaces and Microdrive.


Tape facilities haven't been forgotten either, but the ZX


printer just doesn't have enough characters per line to


produce a useful printout from this type of program.








Entering the listing





Listing 1 is for the Wafadrive and uses the Wafadrive's


Centronics port to feed the printer. Simply enter the


listing and run the program. Should you wish to use


Microdrive, modify the appropriate LOAD/SAVE commands in the


routine starting at line 5000 but note the different way in


which the Wafadrive handles the loading and saving of data.


Enter listing 2 instead of lines 3000 to 3420 if you wish to


use the Kempston 'E' interface. Listing 2 should be easily


modified to suit other interfaces. Interface software should


be entered instead of line 3020 and lines 3340, 3360, 3390


and 3410, which remove or implement Spectrum command word


tokens, should be either left out or substituted with those


required by your interface. If you wish to use a printer


other than the Epson or Star you will have to check the


printer codes against those given in your printer manual. If


you do not have the Wafadrive, you will be unable to enter


some of the lines as these use the Wafadrive's Extended


Basic. Don't enter these lines, which only occur in the


Load/Save routine. Modify the Menu accordingly.








Program Description





The program, which stores information entered in a three


dimensional array, uses the Spectrum's string handling


facilities extensively, particularly when handling the


screen display. It is menu driven and features eight


principal routines. A description of these is given in


figure 1.








Enter and/or Amend Data (Lines 2000-2510)





This routine is the heart of the program and is probably the


most complex. It works by slicing the three dimension array


A$, defined during initialisation, and printing on the


screen in two 'Windows'. These windows correspond to the


following screen locations. Line 0, Column 8, and Line 20,


Column 31. A '*' cursor which may be moved to any position


on the screen using the cursor keys, or to the next column


by depressing ENTER should be positioned where it is


required to enter or amend data. If the cursor moves off the


screen in any direction the appropriate window is reprinted.


A slight pause is experienced at this point. The Enter/Amend


option MUST NOT be selected unless the program has either


been Formatted, or a Data File loaded otherwise an error


will result.





Sub-totals at any line may be selected by entering a 'T' in


the first space of the column where it is required. These


markers should be entered each time a calculation, or


recalculation is made as the calculation routine removes


them.








Printer Routine (Lines 3000-5420)





The listing of this routine in the main program uses the


Wafadrive's centronics port. If, however, you do not have a


Wafadrive, listing 2 will give you the same printer


facilities via the Kempston 'E' interface. Both listings are


for Epson or Star printers but should be easy to modify for


other printers. The routine provides an extensive range of


formats and up to 136 characters per line may be printed in


condensed mode. If you have selected a format containing


more than 6x8 character columns, (excluding Titles and


Totals), you will need to select the condensed printing


mode.








Calculation Routine (Lines 4000-4370)





This routine should only be used if standard eight-character


columns have been formatted. If either, or both, Column and


Line totals have been cancelled (Option 8) then flags will


have been set to prevent the appropriate part of the routine


from functioning. A safeguard is included which will prevent


Totals containing more digits than the column width from


being printed. An audible warning is given during


calculation should this occur. As the routine can take some


time if the array has been extensively filled with data, the


column or line number currently being totalled is displayed


on screen.








SAVE/LOAD routine (Lines 5000-5300)





A comprehensive routine to load/save to tape or wafer which


could easily be adapted for use in other programs. If you


are converting this routine to microdrive it should be noted


that Saving or Loading Data on the Wafadrive is carried out


by reading the different elements of the array A$. This is


achieved with nested loops which are [not] necessary with


tape or microdrive. Note that Column Titles and all the


variables necessary to run an unformatted version of the


program are also saved.








Attributes (Lines 8000-8020)





A simple routine which enables Paper and Ink colours to be


set from the Menu.








Clear numeric data (Lines 6140-6200)





Nested loops are used to clear the array with the exception


of line and column titles. The routine then calls part of


the format routine to allow the option of entering column


markers.








Cancel/reinstate totals (Lines 6000-6130)





This routine prints a menu which gives options to cancel or


reinstate Line and Column Totals. Flags are set and the


array sliced according to the option selected. Data recorded


in these segments is retained in memory. Exercising this


option fully, after formatting without Line/Column Titles or


Column Markers, enables text only to be entered. If you wish


to enter a mixture of text and numeric data then enter


numeric data first, calculate totals (if required), cancel


Line and Column totals and then enter text. If applicable,


Column and Line Totals should be reinstated before sending


data to the printer.








Important points





1. The largest number which can be entered is 9999999 or in decimal


form 9999.99. Totals or sub-totals which exceed this will not be entered.


2. Text comments must not be entered before totals have been calculated.


3. The program must be INITIALISED or DATA LOADED before selecting any of


the other MENU options.


4. Should the program return to BASIC for any reason it may be restarted


with GO TO 1. Do not use RUN as this will clear all data entered.








Figure 1. Description of main routines.





2000-2060 Defines certain variables representing either a screen location


or the corresponding position in the array A$ and then prints the


initial screen display.


2070-2220 The Input Logo. This loop enables the cursor to be moved and data


to be entered or deleted as required. Subroutines located at lines


2230-2510 are called to print on screen as required. The principle


options available are:


Caps shift + '5' - Move cursor left


Caps shift + '6' - Move cursor down


Caps shift + '7' - Move cursor up


Caps shift + '8' - Move cursor right


Symb.shift + 'A' - Return to menu


Symb.shift + ':' - Print':' at cursor


Delete - Delete at cursor, and backspace.


Enter - Move cursor to first position of next column. If end of


array, print cursor at beginning of next line


ASC 2 Character - Print at cursor position


'T' - Entered to indicate the position of a sub-total.


2230-2310 Reprint screen display if cursor moves off right-hand edge.


2320-2370 Reprint screen display if cursor moves off left-hand edge.


2380-2420 Reprint screen display if cursor moves off top edge.


2430-2470 Reprint screen display if cursor moves off bottom edge.


2480-2490 'Enter' Subroutine.


3000-3170 Print on-screen a menu of various printer codes and format options.


A little practice will enable you to select an appropriate format


and print it anywhere desired on A4 paper. The BOX option is used


to print out numeric data in the form of a table and should be


used in conjunction with LINE SPACING for optimum effect. Print


options are cancelled when printing is completed and must be


re-entered if a copy is required.


3180-3310 Requests the input of a title and sends to the printer the data


to be printed.


4010-4070 Checks to see if the appropriate Totals flags have been reset.


If not, goes to the appropriate subroutine.


4080-4200 Sets all column totals initially to 0 and enters series of nested


loops to total each column. Safeguards included in lines 4150 and


4160 prevent the program crashing if a null entry is found, or the


total becomes too big.


4210-4350 Similar routine for Line Totals.


4360-4370 Minor subroutine to set keyboard 'click'.





REFORMAT/INITIALISE ... LINES 9000-9440





When using the program for the first time it must be formatted. To


do this select option 1 from the Main Menu.





LINE NUMBERS DESCRIPTION


9010 Gives the opportunity to return to the menu if the option has


been chosen in error.


9020-9170 This section permits you to define up to 15 column titles, each


eight spaces wide. Line Titles and Totals columns are not included


as they are formatted automatically. The maximum width of the


array A$ is 136 characters, which corresponds to the number of


characters which can be printed in condensed mode.


9180-9310 Routine for entering Line Titles. Up to 99 titles may be entered.


If you wish to enter text commands you may enter a blank title in


the appropriate line. This facility is also available when entering


column titles. Used together it is possible to format the program


to the required dimensions without entering titles and should be


used if only text entry, or columns of non-standard width are


required. Titles may then be entered from the main program.


9320-9340 Permits column markers to be entered and should only be selected


if columns of a standard eight character width are required.


9340-9450 Defines certain variables used by the Printer Routine.








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