Introduction

Welcome to SLP-VISICALC, the electronic spreadsheet service for the Emulator.ca Systems BBS network.

In 1979, something remarkable happened in a small Cambridge apartment. Dan Bricklin and Bob Frankston created VisiCalc—and in doing so, they transformed the personal computer from a hobbyist's curiosity into an indispensable business tool. Accountants who had spent careers hunched over columnar pads suddenly discovered they could change one number and watch an entire financial model recalculate before their eyes. The Apple II, once dismissed as a toy, found its way into Fortune 500 boardrooms. Software Applications Associates could scarcely keep up with demand.

VisiCalc was not merely a program. It was, as one industry observer noted, "the software tail that wagged the hardware dog." Businesses bought computers specifically to run VisiCalc. For the first time, software—not silicon—drove purchasing decisions.

Now, through your modem connection to the Emulator.ca Systems network, you can experience this watershed moment in computing history. SLP-VISICALC faithfully recreates the command structure and calculation engine of the original, letting you build financial models, track budgets, and explore the elegance of the electronic spreadsheet.

The SLP-VISICALC service provides:

• Full 80-column worksheet display with labeled rows (1-254) and columns (A-BK)
• Instant recalculation of dependent formulas as you type
• Text labels and numeric values in any cell
• Range-based functions including @SUM, @AVG, @MIN, and @MAX
• Replicate, insert, delete, and clear commands for efficient editing
• Cell address navigation with the >A1 go-to command
• VT100-compatible screen updates optimized for dial-up connections

Whether you are balancing a household budget, projecting quarterly sales, or simply curious about the software that launched an industry, SLP-VISICALC invites you to discover why millions found the electronic spreadsheet indispensable.

Quick Start

New to spreadsheets? Follow these steps to create your first worksheet in under two minutes.

Step 1: Dial the SLP-VISICALC service:

ATDT555-0350

Step 2: Once connected, you will see READY: A1 indicating the cursor is at cell A1. Type a label for your first column:

'ITEM

The apostrophe tells VisiCalc this is a text label.

Step 3: Press the down arrow or type >A2 to move to cell A2. Enter more labels:

'Rent
>A3
'Food
>A4
'Utilities
>A5
'TOTAL

Step 4: Move to B1 and enter a column header and values:

>B1
'AMOUNT
>B2
850
>B3
200
>B4
75

Step 5: In B5, enter a formula to sum your expenses:

>B5
@SUM(B2..B4)

The total appears instantly. Change any value in B2 through B4 and watch the sum update automatically—this is the essence of the electronic spreadsheet.

Getting Connected

Configure your modem for dial-out and issue the following command:

ATDT555-0350

Once connected, the worksheet appears with a status line and the cell cursor:

Worksheet Basics

Cell Addressing

Each cell is addressed by column letter and row number. Columns start at A and rows start at 1. Examples: A1, B3, H12.

Moving the Cursor

Use the arrow keys or control keys supported by your terminal to move the cell cursor. The current cell is shown on the status line.

Entering Labels and Values

To enter a label (text), type a single quote before the text. Labels are displayed as left-justified text.

To enter a value (number), type the number directly. Values are right-justified and can be used in formulas.

Formulas & Functions

Formulas are the heart of the electronic spreadsheet—they transform a grid of numbers into a living model that responds to change. When you modify one value, every formula that depends on it recalculates automatically. This is the magic that made accountants' jaws drop in 1979.

Arithmetic Operators

Formulas begin with + or = and can include any combination of these operators:

Order of Operations

VisiCalc follows standard mathematical precedence:

1. Parentheses (innermost first)
2. Exponentiation (^)
3. Multiplication and Division (*, /) — left to right
4. Addition and Subtraction (+, -) — left to right

Use parentheses to override precedence when needed:

+A1+B1*C1     means A1 + (B1 × C1)
+(A1+B1)*C1   means (A1 + B1) × C1

Range Syntax

Ranges are specified with two cell addresses separated by ... The range includes both corners and everything between them:

Built-In Functions

Functions use the @ prefix and operate on ranges or individual values:

Combining Formulas and Functions

You can use functions within larger formulas:

E1: +@SUM(A1..A10)*1.15    (sum plus 15%)
E2: +@AVG(B1..B10)/12      (monthly average)
E3: +C1-@MIN(C1..C10)      (distance from minimum)

Command Summary

Commands begin with a slash (/) and operate on the current cell or selected range.

Worked Examples

These complete examples demonstrate VisiCalc's power for real-world problems. Type them exactly as shown to build working models you can modify for your own needs.

Monthly Budget

Track expenses across three months with automatic totals and averages:

Now change any expense value and watch the totals recalculate instantly. This is the essence of "what-if" analysis—the reason businesses bought computers to run VisiCalc.

Sales Commission Calculator

Calculate commissions with tiered rates:

Loan Payment Estimator

Rough monthly payment calculation:

Replicating Formulas

The /R command (Replicate) copies cells with automatic reference adjustment. When you replicate a formula, VisiCalc adjusts cell references based on the relative position:

/R E2...E2 E3...E10   (replicate E2 to E3 through E10)

If E2 contains @SUM(B2...D2), then:

• E3 becomes @SUM(B3...D3)
• E4 becomes @SUM(B4...D4)
• And so on...

This "relative reference" behavior is what makes spreadsheets practical. Instead of typing the same formula pattern dozens of times, you type it once and replicate.

Appendix A: Quick Reference Card

┌─────────────────────────────────────────────────────────────┐
│              SLP-VISICALC QUICK REFERENCE                   │
│              Emulator.ca Systems                            │
├─────────────────────────────────────────────────────────────┤
│  MOVEMENT                                                   │
│    Arrow keys    Move cursor one cell                       │
│    >A1           Go to cell A1 (or any address)             │
│    Home          Return to cell A1                          │
├─────────────────────────────────────────────────────────────┤
│  ENTRY                                                      │
│    'text         Enter a label (text)                       │
│    123           Enter a numeric value                      │
│    +A1*B1        Enter a formula (+ or = prefix)            │
├─────────────────────────────────────────────────────────────┤
│  COMMANDS (begin with /)                                    │
│    /B            Blank current cell                         │
│    /C Y          Clear entire sheet (Y confirms)            │
│    /D R|C        Delete row or column                       │
│    /I R|C        Insert row or column                       │
│    /R src dst    Replicate range (e.g. /R A1...A3 B1...B3)  │
│    /V            Version info                               │
├─────────────────────────────────────────────────────────────┤
│  FUNCTIONS (@ prefix)                                       │
│    @SUM(A1..A10)   Sum of range                             │
│    @AVG(A1..A10)   Average of range                         │
│    @MIN(A1..A10)   Minimum value in range                   │
│    @MAX(A1..A10)   Maximum value in range                   │
├─────────────────────────────────────────────────────────────┤
│  RANGE SYNTAX                                               │
│    A1..A10       Vertical range (column)                    │
│    A1..D1        Horizontal range (row)                     │
│    A1..D10       Rectangular block                          │
└─────────────────────────────────────────────────────────────┘

Appendix B: Troubleshooting

Problem: The screen displays garbled characters or does not update properly.

Solution: Ensure your terminal emulation is set to VT100 or ANSI mode. Check that your modem connection is stable—line noise can corrupt screen updates. Try reconnecting if screen corruption persists.

Problem: Formulas display as text instead of calculating.

Solution: Formulas must begin with + or = to be recognised as calculations. If you typed A1*2, the system interprets this as a label. Enter +A1*2 or =A1*2 instead.

Problem: The @SUM function returns zero even though cells contain values.

Solution: Verify that the cells contain numeric values, not labels. A cell beginning with an apostrophe (like '100) is stored as text and ignored by calculations. Re-enter the value without the leading apostrophe.

Problem: Changes to one cell do not update dependent formulas.

Solution: SLP-VISICALC recalculates automatically after each edit. If formulas are not updating, verify that dependent cells contain valid numeric values and that formulas are correctly entered (beginning with + or =).

Problem: The cursor moves erratically or skips cells.

Solution: Some terminal programs send non-standard escape sequences for arrow keys. Try using the go-to command (>A1) for navigation, or consult your terminal software documentation for VT100 compatibility settings.

Problem: Division by zero error.

Solution: A formula is attempting to divide by a cell that contains zero or is empty. Check that all divisor cells contain valid non-zero values. Consider using a conditional formula or restructuring your worksheet to avoid this case.

Problem: Copied formulas reference wrong cells.

Solution: VisiCalc adjusts references when copying. If you copy from row 5 to row 8, references move down 3 rows. Verify the copied formula by navigating to the cell and viewing its contents. You may need to edit individual cells if the automatic adjustment is not what you intended.

Problem: Worksheet is slow to respond.

Solution: Large worksheets with many interdependent formulas can take time to recalculate after each change. Wait for recalculation to complete before entering the next value. On particularly complex worksheets, consider whether you can simplify the formula structure.

Appendix C: Glossary

Cell — The intersection of a row and column, identified by a column letter and row number (e.g., B3). Each cell can hold a label, value, or formula.

Column — A vertical stack of cells, identified by letters A through BK.

Formula — An expression that calculates a value based on the contents of other cells. Formulas begin with + or = and may include cell references, operators, and functions.

Function — A built-in calculation that operates on a value or range of values. VisiCalc functions begin with the @ symbol (e.g., @SUM).

Label — Text stored in a cell, used for headings, descriptions, or notes. Labels begin with an apostrophe and are not included in calculations.

Range — A rectangular group of cells specified by two corner addresses separated by .. (e.g., A1..D10).

Recalculation — The process by which the spreadsheet updates all formulas to reflect current values. SLP-VISICALC recalculates automatically after each edit.

Replicate — The /R command that copies a range of cells to a new location, automatically adjusting cell references based on relative position.

Row — A horizontal series of cells, identified by numbers 1 through 254.

Value — A numeric entry in a cell that can be used in calculations.

Worksheet — The entire grid of cells that makes up a VisiCalc document.

Tips for Effective Spreadsheets

These practices will help you build worksheets that are easy to understand, modify, and trust.

Design Before You Type — Sketch your worksheet layout on paper first. Decide what data goes where, what calculations you need, and how the results should be organised. A few minutes of planning saves hours of rearranging.

Label Everything — Use row and column headers liberally. A worksheet you understand today may be mysterious in six months. Labels cost nothing and clarify everything.

Keep Formulas Simple — Break complex calculations into steps across multiple cells. Instead of one monster formula, use intermediate cells with clear labels. This makes debugging much easier and documents your logic.

Test With Known Values — Before trusting a worksheet for real decisions, enter test data with results you can verify by hand. If the worksheet says 2+2=5, you have a problem to find.

Use Ranges, Not Lists — @SUM(A1..A12) is easier to read and extend than +A1+A2+A3+A4+A5+A6+A7+A8+A9+A10+A11+A12. When you add a row, the range formula adapts automatically.

Document Assumptions — Use label cells to note important assumptions: "Assumes 8% annual growth" or "Tax rate as of 1985." When assumptions change, you will know what to update.

The electronic spreadsheet rewards careful thought. A well-designed worksheet becomes a trusted tool you return to again and again.