Commodore BASIC V2

The Gateway to Programming

Commodore BASIC V2 was the first programming language encountered by millions of computer users in the 1980s. Built into every Commodore 8-bit computer from the PET to the C64, it served as both an operating system interface and a gentle introduction to programming concepts.

Language Characteristics

Line-Oriented Programming

BASIC V2 used numbered lines for program structure:

10 PRINT "WHAT IS YOUR NAME?"
20 INPUT N$
30 PRINT "HELLO "; N$
40 GOTO 10

Immediate Mode

Commands could be executed immediately without line numbers:

PRINT 2+2          REM Prints 4 immediately
FOR I=1 TO 10: PRINT I: NEXT    REM Loop executes now

Core Commands

Program Flow

• GOTO - Unconditional jump
• GOSUB/RETURN - Subroutine calls
• IF...THEN - Conditional execution
• FOR...NEXT - Loop structures
• ON...GOTO - Computed branches

Variables and Data

• LET A=5 - Variable assignment (LET optional)
• DIM A(10) - Array declaration
• READ/DATA - Data statements
• INPUT - User input
• GET - Single character input

File Operations

• LOAD "PROGRAM" - Load program from disk/tape
• SAVE "PROGRAM" - Save current program
• OPEN 1,8,15 - Open file for I/O
• PRINT#1,"DATA" - Write to file
• INPUT#1,A$ - Read from file
• CLOSE 1 - Close file

Platform-Specific Features

VIC-20 Enhancements

Graphics and sound capabilities:

POKE 36878,15      REM Set volume
POKE 36876,200     REM Set frequency
POKE 36869,255     REM Set screen color

C64 Graphics and Sound

More sophisticated multimedia:

POKE 53280,0       REM Black border
POKE 53281,1       REM White background
POKE 54296,15      REM Full volume

Memory Management

Program Storage

• C64: Programs stored from $0801-$9FFF
• Available RAM: ~38KB for BASIC programs
• Variable space: Follows program code
• String space: Top of memory downward

Memory Peek/Poke

Direct memory access:

POKE 1024,1        REM Write to screen memory
A = PEEK(1024)     REM Read from memory

Programming Techniques

Simple Games

Classic programming exercises:

100 REM GUESS THE NUMBER
110 N = INT(RND(1)*100)+1
120 INPUT "GUESS"; G
130 IF G=N THEN PRINT "CORRECT!": END
140 IF G<N THEN PRINT "TOO LOW"
150 IF G>N THEN PRINT "TOO HIGH"
160 GOTO 120

Screen Manipulation

Text graphics and animation:

10 FOR I=1024 TO 2023
20 POKE I,42          REM Fill screen with asterisks
30 NEXT I

Limitations and Workarounds

Missing Features

BASIC V2 lacked many modern conveniences:

• No dedicated graphics commands
• Limited sound support
• No structured programming constructs
• Slow execution speed
• No error line numbers

Common Solutions

Programmers developed techniques:

REM Use variables for commonly used values
10 SC=1024: BC=53280: VOL=54296
20 POKE BC,0: POKE VOL,15

Educational Impact

Learning Programming Concepts

BASIC V2 taught fundamental programming:

• Variables and data types
• Program flow control
• Input/output operations
• Problem decomposition
• Debugging skills

Accessibility

Features that made programming approachable:

• English-like commands
• Immediate feedback
• Built-in help (LIST, RUN, STOP)
• Forgiving error handling
• Visual program structure

Performance Characteristics

Execution Speed

BASIC V2 was interpreted, making it slow:

• Line number lookup on GOTO/GOSUB
• Variable name parsing each use
• Tokenization overhead
• No optimization

Memory Usage

Efficient use of limited RAM:

• Tokenized storage (keywords as single bytes)
• Compact variable storage
• Shared string space
• Dynamic memory allocation

Advanced Techniques

Machine Language Integration

Calling assembly routines:

10 POKE 49152,169: POKE 49153,65    REM LDA #65
20 POKE 49154,32: POKE 49155,210    REM JSR $FFD2
30 POKE 49156,255: POKE 49157,96    REM RTS
40 SYS 49152                        REM Call routine

Custom Functions

Using DEF FN:

10 DEF FN SQ(X) = X*X
20 PRINT FN SQ(5)    REM Prints 25

Historical Context

Origins

• Based on Microsoft BASIC-80
• Licensed from Microsoft by Commodore
• Adapted for 6502 processor
• Integrated with KERNAL ROM

Market Impact

• Standardized home computer programming
• Created common programming experience
• Enabled software sharing between systems
• Established BASIC as beginner language

Modern Relevance

Educational Value

BASIC V2 remains valuable for teaching:

• Programming fundamentals
• Computer architecture understanding
• Historical computing context
• Problem-solving skills

Preservation

Important for:

• Software archaeology
• Emulation accuracy
• Historical documentation
• Educational research

Modern Implementations

Contemporary BASIC interpreters maintain V2 compatibility:

• CBM prg Studio
• BASIC 10Liner contests
• Retro programming exercises
• Educational tools

Legacy and Influence

Language Evolution

BASIC V2 influenced later versions:

• GW-BASIC adopted similar syntax
• QBasic maintained compatibility
• Modern BASIC dialects preserve core concepts
• Educational programming languages borrowed ideas

Cultural Impact

Beyond technical influence:

• Democratized programming
• Created generation of programmers
• Established home computing culture
• Influenced computer education

Conclusion

Commodore BASIC V2, despite its limitations, served as the perfect introduction to programming for millions of users. Its simplicity, immediate feedback, and integration with the operating system created an environment where programming felt natural and accessible.

While modern languages offer more features and better performance, BASIC V2’s educational approach and gentle learning curve remain relevant today. It represents a time when programming was an expected part of computer ownership, not a specialized skill, making it a fascinating study in both computer science and social history.