QUANTUM BASIC 7.1 · VERSION 1.1.0

Quantum Basic 7.1

Professional Development System v1.1.0

A QuickBASIC / PDS 7.1 compatible compiler for 64-bit Windows. Write BASIC the way you always have, and get a native x64 program out the other end. Old programs that poke video memory or call DOS interrupts keep working, and many QB64 extensions work too.

▼ Download Quantum Basic 7.1

QuantumBASIC.zip · Version 1.1.0 · Windows 64-bit

What's new in 1.1.0

Raw sound streaming: _SNDRAW, _SNDRATE and _SNDRAWLEN. Programs can now generate their own audio sample by sample (synthesizers, chip-music players, sound effects) and it plays alongside sounds loaded with _SNDOPEN.

What it does

Compiles QuickBASIC and PDS 7.1 programs to native 64-bit Windows executables
Supports many QB64 extensions: _NEWIMAGE, _PUTIMAGE, _LOADIMAGE, _KEYDOWN, _SNDOPEN, _MEM and more
Graphics in every SCREEN mode through an SDL2 window, including 32-bit color screens
Emulates the DOS memory map, so DEF SEG, PEEK, POKE, CALL ABSOLUTE and CALL INTERRUPT still do what they used to
Sound from WAV and OGG files, plus raw sample streaming
An IDE with editor, color schemes and F1 help in the classic PDS 7.1 blue

How it works

Quantum Basic is a real compiler, not an interpreter. Your program goes through the same stages as a C compiler and ends up as x64 machine code, linked against the Quantum Basic runtime library.

program.bas └─ Lexer keywords, literals, type suffixes └─ Parser builds the syntax tree └─ Resolver checks names, types and scopes └─ IR lowers BASIC into a simple intermediate form └─ Codegen emits x64 assembly (NASM) └─ Link + librt.a (runtime) → program.exe

The runtime library (librt.a) is where the BASIC statements actually do their work. Two of its parts are written specially for Quantum Basic: rt_graphics_sdl2 and rt_cpu_emu.

rt_graphics_sdl2 — the graphics and sound engine

Every compiled program opens an SDL2 window, and rt_graphics_sdl2 draws everything that appears in it. It recreates the screen modes of a VGA-era PC pixel for pixel, then scales the picture to fit a modern monitor.

Screen modes and text

SCREEN 0 through SCREEN 13 with the original resolutions, colour counts and default palettes, including the 256-colour VGA palette of SCREEN 13
QB64 32-bit colour screens and off-screen images with _NEWIMAGE
PRINT, LOCATE, COLOR and VIEW PRINT in every mode, with the full CP437 character set (box-drawing, accented letters, symbols) in built-in 8×8, 8×14 and 8×16 fonts
Blinking text, and a blinking cursor for INPUT in graphics modes
TrueType fonts with _LOADFONT and _FONT when SDL2_ttf.dll is present (programs still start without it)

Drawing

PSET, PRESET, LINE (boxes, filled boxes, styled lines), CIRCLE (arcs and ellipses), PAINT and DRAW
VIEW viewports, WINDOW coordinates and PMAP
PALETTE and PALETTE USING
Sprites with GET and PUT (PSET, PRESET, AND, OR, XOR)
Multiple screen pages with PCOPY for flicker-free animation

QB64 images, input and window

Image handles: _NEWIMAGE, _LOADIMAGE (BMP, PNG, JPG, GIF), _PUTIMAGE with scaling, _DEST, _SOURCE, _SETALPHA, _FREEIMAGE
Colour functions: _RGB32, _RGBA32, _RED32 and friends
Keyboard: INKEY$, _KEYDOWN (several keys held at once), _KEYHIT, _KEYCLEAR
Mouse: _MOUSEINPUT, _MOUSEX, _MOUSEY, _MOUSEBUTTON
Window: _TITLE, _ICON, _FULLSCREEN, _SCREENMOVE, and smooth game loops with _DISPLAY and _LIMIT
Simple on-screen controls: BUTTON, CHECKBOX, RADIOBUTTON

Sound

A 32-voice software mixer: up to 32 sounds play at once, each with its own volume (_SNDVOL) and left/right balance (_SNDBAL)
WAV (PCM, float and ADPCM) and Ogg Vorbis files with _SNDOPEN, _SNDPLAY, _SNDLOOP, _SNDPLAYCOPY, _SNDPLAYFILE and the rest of the QB64 sound set
New in 1.1.0: _SNDRAW streams samples you calculate yourself, mixed in with the voices above

' a one-second 440 Hz beep, made sample by sample
FOR i = 1 TO _SNDRATE
    _SNDRAW SIN(i / _SNDRATE * 440 * 6.2832) * 0.3
NEXT i
DO: LOOP WHILE _SNDRAWLEN

rt_cpu_emu — the DOS memory and CPU emulator

Many classic BASIC programs reach past BASIC and talk to the PC directly: they POKE straight into video memory, read the keyboard flags from the BIOS data area, or run small machine-code routines. On 64-bit Windows those addresses don't exist, and touching them would crash the program. rt_cpu_emu is a custom-written layer that recreates that old PC world inside your program, so the code runs as it did under DOS.

An emulated real-mode memory map

Address	What happens
&HA000	VGA graphics memory. In `SCREEN 13` each byte you `POKE` is a pixel, and it shows up in the window in the right palette colour. `PEEK` reads it back.
&HB800	Colour text memory: the 80×25 grid of characters and attribute bytes. Programs that draw screens by poking text memory display correctly.
&H0000–&H9FFF	Conventional memory, including the interrupt table and the BIOS data area. It starts out filled in the way a real BIOS leaves it: Caps/Num/Scroll Lock state taken from your keyboard, 640K of memory, colour 80-column display.
DEF SEG = 0	Addresses from `VARPTR` and `SADD` go straight to your program's own variables, so the `PEEK`/`POKE` tricks that work on BASIC data still work.

' fill the SCREEN 13 display through video memory
SCREEN 13
DEF SEG = &HA000
FOR i = 0 TO 63999: POKE i, i MOD 256: NEXT i
DEF SEG

CALL ABSOLUTE and CALL INTERRUPT

CALL ABSOLUTE runs the 16-bit machine code the program built in an array through a small built-in 8086 interpreter, with its own registers and stack. It covers the short routines BASIC programs typically carried: register loads, PUSH/POP, INT calls and RET.
Interrupts made from that code, or from CALL INTERRUPT and CALL INTERRUPTX with a RegType structure, are answered by emulated DOS and BIOS services and carried out with Windows: DOS functions (INT 21h), video (INT 10h), the mouse driver (INT 33h) and the printer (INT 17h).

The result: programs written for real DOS hardware in the 1980s and 1990s can be compiled and run as 64-bit Windows programs, usually without changing a line.

Getting started

Download the zip and extract it to a folder. Then use the IDE or the command line.

The IDE: double-click qb71ide.exe. Write your program in the editor, then compile and run it from there. Press F1 for help on any keyword.

Important: every new program must be saved before you run it in the IDE.

The command line: open a command prompt in the folder and compile your program:

C:\QuantumBASIC> qb71 program.bas

That makes program.exe in the same folder. Run qb71 -h to see all the options.

Requirements

Windows 7 64-bit or later
Optional: SDL2_ttf.dll next to your program for TrueType fonts