BIT

Introduction

BIT is a programming language in which the programmer has full access to all data in its essential machine representation. This is a powerful programming tool, allowing manipulations of data that are convoluted in "higher-level" languages with various specialised functions that operate on more complicated and abstract data types.

Design Principles

Extend the ease of string processing in C to other, more basic, data types such as integers.
Extend the terseness of COBOL to more fundamental code constructs, such as numeric literals.

Language Concepts

Data

Data values are stored in memory as contiguous arrays of bits. This is actually true of all programming languages, but most hide this fundamental representation and make it difficult to operate on the data!

Data Types

BIT is a strongly typed language. There are two data types:

bit - A bit variable can hold one bit of data.
address-of-a-bit - An address-of-a-bit variable holds the memory address of one bit of data.

Jump Register

One bit of memory is reserved as a jump register. It can be written to, and controls program flow via the GOTO statement. It is a bit variable and cannot store an address-of-a-bit.

Utility Functions

These just make a language harder to understand, so BIT has none.

Free Structure

Rather than requiring a rigid syntactical structure, BIT supports any amount of whitespace, including line breaks, between syntax elements. This includes no whitespace at all, if it is important to write source code with the smallest possible file size.

Syntax Elements

Bit Constants

To make the language easily writable and readable by humans, the abstract binary digit representations "0" and "1" are not supported. Instead there are two easily-legible constant values defined as follows:

ZERO - this represents a binary digit with a value of zero.
ONE - this represents a binary digit with a value of one.

Line Numbers

Program flow is controlled by line numbers. Lines are numbered in binary, using the bit constants, prefixed by the keyword LINE NUMBER. Each line number must be unique. To indicate the end of a line number and the beginning of the code for that line, use the keyword CODE.

Flow Control

Program flow is controlled by GOTO statements. If a line contains no GOTO statement that applies to indicate what statement to execute next, program execution terminates. There are two types of GOTO:

GOTO line-number - causes the next line of code to be executed to be the line with the given number.
GOTO line-number IF THE JUMP REGISTER IS bit-constant - causes the next line of code to be executed to be the line number after the GOTO if the jump register is equal to the given bit constant. Note that the bit constant must be ONE or ZERO, it cannot be a variable expression.

The first type may not be combined with another GOTO on the same line. The second type may appear twice on one line of code, once with the bit constant ZERO and once with the bit constant ONE.

Variables

Variables are identified with names, which must be sequences of bit constants (of course). Variable names begin with the VARIABLE keyword and are followed by an identifying sequence of bit constants:

VARIABLE bit-constants

Variables may hold either a bit value, or an address-of-a-bit value.

Operators

The following operators are available. These are, in order of precedence:

THE VALUE AT - unary operator returning the bit value at the address-of-a-bit held by the variable on the right. This only makes sense for address-of-a-bit variables; attempting to take THE VALUE AT a bit variable is an error.
THE VALUE BEYOND - unary operator returning the bit value in the next memory address beyond the address-of-a-bit held by the variable on the right. This only makes sense for address-of-a-bit variables; attempting to take THE VALUE BEYOND a bit variable is an error.
THE ADDRESS OF - unary operator returning the address-of-a-bit of the bit variable on the right. This only makes sense for bit variables; attempting to take THE ADDRESS OF an address-of-a-bit variable is an error. Attempting to take THE ADDRESS OF THE JUMP REGISTER is also an error.
NAND - binary operator returning ZERO if both bit operands are ONE, returning ONE if either is ZERO. Ir either operand is an address-of-a-bit, this is an error.
EQUALS - the assignment operator. Sets the variable on the left to the value of the expression on the right. The variable on the left may be THE JUMP REGISTER. Bit values may only be assigned to bit variables, and address-of-a-bit values may only be assigned to address-of-a-bit variables; anything else is an error.

There are also grouping operators to allow changing the default precedence of the operators:

OPEN PARENTHESIS
CLOSE PARENTHESIS

These work like the standard arithmetic grouping operators "(" and ")".

Commands

PRINT bit-constant - this prints the bit constant to standard output. This command can only print one bit; to print several bits you need to use several PRINT statements in a row (noting that only one PRINT statement can appear per line of code). Attempting to print a variable (of either type) is an error.
Note that BIT can only print bit values. Many other languages abstract this binary data into decimal numbers and strings, thus hiding the underlying data. To avoid any possibility of confusion by this abstraction process, BIT does not support printing non-binary numbers or character strings, or even digits or characters.
If you wish to represent character data, you can print a sequence of bits that can be interpreted as an ASCII code for a character. You should make it clear to whoever runs the code that they will need an ASCII reference table to interpret the output in this way.
READ - this reads a bit from the standard input and sets the jump register equal to that bit.
Again note that only a single bit is read per READ statement, and a bit sequence that may represent an ASCII character needs to be read in one bit at a time.

Sample Programs

Bit Addition

This program reads any two bits and prints the result of adding them together. The power of BIT is self-evident here.

LINE NUMBER ONE CODE READ GOTO ONE ZERO
LINE NUMBER ONE ZERO CODE VARIABLE ZERO EQUALS THE JUMP REGISTER GOTO ONE ONE
LINE NUMBER ONE ONE CODE READ GOTO ONE ZERO ZERO
LINE NUMBER ONE ZERO ZERO CODE VARIABLE ONE EQUALS THE JUMP REGISTER GOTO ONE ZERO ONE
LINE NUMBER ONE ZERO ONE CODE THE JUMP REGISTER EQUALS OPEN PARENTHESIS VARIABLE ZERO NAND VARIABLE ONE CLOSE PARENTHESIS NAND OPEN PARENTHESIS VARIABLE ZERO NAND VARIABLE ONE CLOSE PARENTHESIS GOTO ONE ONE ZERO IF THE JUMP REGISTER IS EQUAL TO ONE GOTO ONE ZERO ZERO ZERO IF THE JUMP REGISTER IS EQUAL TO ZERO
LINE NUMBER ONE ONE ZERO CODE PRINT ONE GOTO ONE ONE ONE
LINE NUMBER ONE ONE ONE CODE PRINT ZERO
LINE NUMBER ONE ZERO ZERO ZERO CODE THE JUMP REGISTER EQUALS OPEN PARENTHESIS VARIABLE ZERO NAND VARIABLE ZERO CLOSE PARENTHESIS NAND OPEN PARENTHESIS VARIABLE ONE NAND VARIABLE ONE CLOSE PARENTHESIS GOTO ONE ZERO ZERO ONE IF THE JUMP REGISTER IS EQUAL TO ZERO GOTO ONE ZERO ONE ZERO IF THE JUMP REGISTER IS EQUAL TO ONE
LINE NUMBER ONE ZERO ZERO ONE CODE PRINT ZERO
LINE NUMBER ONE ZERO ONE ZERO CODE PRINT ONE

Note that this code is formatted rather verbosely with whitespace. The following version is just as valid, and possesses considerable advantages in file size savings:

LINENUMBERONECODEREADGOTOONEZEROLINENUMBERONEZEROCODEVARIABLEZEROEQUALSTHEJUMPR
EGISTERGOTOONEONELINENUMBERONEONECODEREADGOTOONEZEROZEROLINENUMBERONEZEROZEROCO
DEVARIABLEONEEQUALSTHEJUMPREGISTERGOTOONEZEROONELINENUMBERONEZEROONECODETHEJUMP
REGISTEREQUALSOPENPARENTHESISVARIABLEZERONANDVARIABLEONECLOSEPARENTHESISNANDOPE
NPARENTHESISVARIABLEZERONANDVARIABLEONECLOSEPARENTHESISGOTOONEONEZEROIFTHEJUMPR
EGISTERISEQUALTOONEGOTOONEZEROZEROZEROIFTHEJUMPREGISTERISEQUALTOZEROLINENUMBERO
NEONEZEROCODEPRINTONEGOTOONEONEONELINENUMBERONEONEONECODEPRINTZEROLINENUMBERONE
ZEROZEROZEROCODETHEJUMPREGISTEREQUALSOPENPARENTHESISVARIABLEZERONANDVARIABLEZER
OCLOSEPARENTHESISNANDOPENPARENTHESISVARIABLEONENANDVARIABLEONECLOSEPARENTHESISG
OTOONEZEROZEROONEIFTHEJUMPREGISTERISEQUALTOZEROGOTOONEZEROONEZEROIFTHEJUMPREGIS
TERISEQUALTOONELINENUMBERONEZEROZEROONECODEPRINTZEROLINENUMBERONEZEROONEZEROCOD
EPRINTONE

Hello World

This program prints a binary representation of the string "Hello world!". Basically, it is just the print statements necessary to print the ASCII bits. I challenge anyone to use other language features to write a shorter "Hello world!" program in BIT.

LINENUMBERZEROCODEPRINTZEROGOTOONELINENUMBERONECODEPRINTONEGOTOONEZEROLINENUMBE
RONEZEROCODEPRINTZEROGOTOONEONELINENUMBERONEONECODEPRINTZEROGOTOONEZEROZEROLINE
NUMBERONEZEROZEROCODEPRINTONEGOTOONEZEROONELINENUMBERONEZEROONECODEPRINTZEROGOT
OONEONEZEROLINENUMBERONEONEZEROCODEPRINTZEROGOTOONEONEONELINENUMBERONEONEONECOD
EPRINTZEROGOTOONEZEROZEROZEROLINENUMBERONEZEROZEROZEROCODEPRINTZEROGOTOONEZEROZ
EROONELINENUMBERONEZEROZEROONECODEPRINTONEGOTOONEZEROONEZEROLINENUMBERONEZEROON
EZEROCODEPRINTONEGOTOONEZEROONEONELINENUMBERONEZEROONEONECODEPRINTZEROGOTOONEON
EZEROZEROLINENUMBERONEONEZEROZEROCODEPRINTZEROGOTOONEONEZEROONELINENUMBERONEONE
ZEROONECODEPRINTONEGOTOONEONEONEZEROLINENUMBERONEONEONEZEROCODEPRINTZEROGOTOONE
ONEONEONELINENUMBERONEONEONEONECODEPRINTONEGOTOONEZEROZEROZEROZEROLINENUMBERONE
ZEROZEROZEROZEROCODEPRINTZEROGOTOONEZEROZEROZEROONELINENUMBERONEZEROZEROZEROONE
CODEPRINTONEGOTOONEZEROZEROONEZEROLINENUMBERONEZEROZEROONEZEROCODEPRINTONEGOTOO
NEZEROZEROONEONELINENUMBERONEZEROZEROONEONECODEPRINTZEROGOTOONEZEROONEZEROZEROL
INENUMBERONEZEROONEZEROZEROCODEPRINTONEGOTOONEZEROONEZEROONELINENUMBERONEZEROON
EZEROONECODEPRINTONEGOTOONEZEROONEONEZEROLINENUMBERONEZEROONEONEZEROCODEPRINTZE
ROGOTOONEZEROONEONEONELINENUMBERONEZEROONEONEONECODEPRINTZEROGOTOONEONEZEROZERO
ZEROLINENUMBERONEONEZEROZEROZEROCODEPRINTZEROGOTOONEONEZEROZEROONELINENUMBERONE
ONEZEROZEROONECODEPRINTONEGOTOONEONEZEROONEZEROLINENUMBERONEONEZEROONEZEROCODEP
RINTONEGOTOONEONEZEROONEONELINENUMBERONEONEZEROONEONECODEPRINTZEROGOTOONEONEONE
ZEROZEROLINENUMBERONEONEONEZEROZEROCODEPRINTONEGOTOONEONEONEZEROONELINENUMBERON
EONEONEZEROONECODEPRINTONEGOTOONEONEONEONEZEROLINENUMBERONEONEONEONEZEROCODEPRI
NTZEROGOTOONEONEONEONEONELINENUMBERONEONEONEONEONECODEPRINTZEROGOTOONEZEROZEROZ
EROZEROZEROLINENUMBERONEZEROZEROZEROZEROZEROCODEPRINTZEROGOTOONEZEROZEROZEROZER
OONELINENUMBERONEZEROZEROZEROZEROONECODEPRINTONEGOTOONEZEROZEROZEROONEZEROLINEN
UMBERONEZEROZEROZEROONEZEROCODEPRINTONEGOTOONEZEROZEROZEROONEONELINENUMBERONEZE
ROZEROZEROONEONECODEPRINTZEROGOTOONEZEROZEROONEZEROZEROLINENUMBERONEZEROZEROONE
ZEROZEROCODEPRINTONEGOTOONEZEROZEROONEZEROONELINENUMBERONEZEROZEROONEZEROONECOD
EPRINTONEGOTOONEZEROZEROONEONEZEROLINENUMBERONEZEROZEROONEONEZEROCODEPRINTONEGO
TOONEZEROZEROONEONEONELINENUMBERONEZEROZEROONEONEONECODEPRINTONEGOTOONEZEROONEZ
EROZEROZEROLINENUMBERONEZEROONEZEROZEROZEROCODEPRINTZEROGOTOONEZEROONEZEROZEROO
NELINENUMBERONEZEROONEZEROZEROONECODEPRINTZEROGOTOONEZEROONEZEROONEZEROLINENUMB
ERONEZEROONEZEROONEZEROCODEPRINTONEGOTOONEZEROONEZEROONEONELINENUMBERONEZEROONE
ZEROONEONECODEPRINTZEROGOTOONEZEROONEONEZEROZEROLINENUMBERONEZEROONEONEZEROZERO
CODEPRINTZEROGOTOONEZEROONEONEZEROONELINENUMBERONEZEROONEONEZEROONECODEPRINTZER
OGOTOONEZEROONEONEONEZEROLINENUMBERONEZEROONEONEONEZEROCODEPRINTZEROGOTOONEZERO
ONEONEONEONELINENUMBERONEZEROONEONEONEONECODEPRINTZEROGOTOONEONEZEROZEROZEROZER
OLINENUMBERONEONEZEROZEROZEROZEROCODEPRINTZEROGOTOONEONEZEROZEROZEROONELINENUMB
ERONEONEZEROZEROZEROONECODEPRINTONEGOTOONEONEZEROZEROONEZEROLINENUMBERONEONEZER
OZEROONEZEROCODEPRINTONEGOTOONEONEZEROZEROONEONELINENUMBERONEONEZEROZEROONEONEC
ODEPRINTONEGOTOONEONEZEROONEZEROZEROLINENUMBERONEONEZEROONEZEROZEROCODEPRINTZER
OGOTOONEONEZEROONEZEROONELINENUMBERONEONEZEROONEZEROONECODEPRINTONEGOTOONEONEZE
ROONEONEZEROLINENUMBERONEONEZEROONEONEZEROCODEPRINTONEGOTOONEONEZEROONEONEONELI
NENUMBERONEONEZEROONEONEONECODEPRINTONEGOTOONEONEONEZEROZEROZEROLINENUMBERONEON
EONEZEROZEROZEROCODEPRINTZEROGOTOONEONEONEZEROZEROONELINENUMBERONEONEONEZEROZER
OONECODEPRINTONEGOTOONEONEONEZEROONEZEROLINENUMBERONEONEONEZEROONEZEROCODEPRINT
ONEGOTOONEONEONEZEROONEONELINENUMBERONEONEONEZEROONEONECODEPRINTZEROGOTOONEONEO
NEONEZEROZEROLINENUMBERONEONEONEONEZEROZEROCODEPRINTONEGOTOONEONEONEONEZEROONEL
INENUMBERONEONEONEONEZEROONECODEPRINTONEGOTOONEONEONEONEONEZEROLINENUMBERONEONE
ONEONEONEZEROCODEPRINTONEGOTOONEONEONEONEONEONELINENUMBERONEONEONEONEONEONECODE
PRINTONEGOTOONEZEROZEROZEROZEROZEROZEROLINENUMBERONEZEROZEROZEROZEROZEROZEROCOD
EPRINTZEROGOTOONEZEROZEROZEROZEROZEROONELINENUMBERONEZEROZEROZEROZEROZEROONECOD
EPRINTONEGOTOONEZEROZEROZEROZEROONEZEROLINENUMBERONEZEROZEROZEROZEROONEZEROCODE
PRINTONEGOTOONEZEROZEROZEROZEROONEONELINENUMBERONEZEROZEROZEROZEROONEONECODEPRI
NTONEGOTOONEZEROZEROZEROONEZEROZEROLINENUMBERONEZEROZEROZEROONEZEROZEROCODEPRIN
TZEROGOTOONEZEROZEROZEROONEZEROONELINENUMBERONEZEROZEROZEROONEZEROONECODEPRINTZ
EROGOTOONEZEROZEROZEROONEONEZEROLINENUMBERONEZEROZEROZEROONEONEZEROCODEPRINTONE
GOTOONEZEROZEROZEROONEONEONELINENUMBERONEZEROZEROZEROONEONEONECODEPRINTZEROGOTO
ONEZEROZEROONEZEROZEROZEROLINENUMBERONEZEROZEROONEZEROZEROZEROCODEPRINTZEROGOTO
ONEZEROZEROONEZEROZEROONELINENUMBERONEZEROZEROONEZEROZEROONECODEPRINTONEGOTOONE
ZEROZEROONEZEROONEZEROLINENUMBERONEZEROZEROONEZEROONEZEROCODEPRINTONEGOTOONEZER
OZEROONEZEROONEONELINENUMBERONEZEROZEROONEZEROONEONECODEPRINTZEROGOTOONEZEROZER
OONEONEZEROZEROLINENUMBERONEZEROZEROONEONEZEROZEROCODEPRINTONEGOTOONEZEROZEROON
EONEZEROONELINENUMBERONEZEROZEROONEONEZEROONECODEPRINTONEGOTOONEZEROZEROONEONEO
NEZEROLINENUMBERONEZEROZEROONEONEONEZEROCODEPRINTZEROGOTOONEZEROZEROONEONEONEON
ELINENUMBERONEZEROZEROONEONEONEONECODEPRINTZEROGOTOONEZEROONEZEROZEROZEROZEROLI
NENUMBERONEZEROONEZEROZEROZEROZEROCODEPRINTZEROGOTOONEZEROONEZEROZEROZEROONELIN
ENUMBERONEZEROONEZEROZEROZEROONECODEPRINTONEGOTOONEZEROONEZEROZEROONEZEROLINENU
MBERONEZEROONEZEROZEROONEZEROCODEPRINTONEGOTOONEZEROONEZEROZEROONEONELINENUMBER
ONEZEROONEZEROZEROONEONECODEPRINTZEROGOTOONEZEROONEZEROONEZEROZEROLINENUMBERONE
ZEROONEZEROONEZEROZEROCODEPRINTZEROGOTOONEZEROONEZEROONEZEROONELINENUMBERONEZER
OONEZEROONEZEROONECODEPRINTONEGOTOONEZEROONEZEROONEONEZEROLINENUMBERONEZEROONEZ
EROONEONEZEROCODEPRINTZEROGOTOONEZEROONEZEROONEONEONELINENUMBERONEZEROONEZEROON
EONEONECODEPRINTZEROGOTOONEZEROONEONEZEROZEROZEROLINENUMBERONEZEROONEONEZEROZER
OZEROCODEPRINTZEROGOTOONEZEROONEONEZEROZEROONELINENUMBERONEZEROONEONEZEROZEROON
ECODEPRINTZEROGOTOONEZEROONEONEZEROONEZEROLINENUMBERONEZEROONEONEZEROONEZEROCOD
EPRINTONEGOTOONEZEROONEONEZEROONEONELINENUMBERONEZEROONEONEZEROONEONECODEPRINTZ
EROGOTOONEZEROONEONEONEZEROZEROLINENUMBERONEZEROONEONEONEZEROZEROCODEPRINTZEROG
OTOONEZEROONEONEONEZEROONELINENUMBERONEZEROONEONEONEZEROONECODEPRINTZEROGOTOONE
ZEROONEONEONEONEZEROLINENUMBERONEZEROONEONEONEONEZEROCODEPRINTZEROGOTOONEZEROON
EONEONEONEONELINENUMBERONEZEROONEONEONEONEONECODEPRINTONE

Repeat Arbitrary Number of Ones

This program demonstrates the use of address-of-a-bit variables to store arbitrarily large amounts of data and access it again. It reads any number of bits from the input until a zero is read, then prints out the sequence of bits read in.

LINE NUMBER ZERO CODE VARIABLE ONE EQUALS THE ADDRESS OF VARIABLE ZERO GOTO ONE
LINE NUMBER ONE CODE READ GOTO ONE ZERO
LINE NUMBER ONE ZERO CODE THE VALUE AT VARIABLE ONE EQUALS THE JUMP REGISTER GOTO ONE ONE IF THE JUMP REGISTER IS ONE GOTO ONE ZERO ZERO IF THE JUMP REGISTER IS ZERO
LINE NUMBER ONE ONE CODE VARIABLE ONE EQUALS THE ADDRESS OF THE VALUE BEYOND VARIABLE ONE GOTO ONE
LINE NUMBER ONE ZERO ZERO CODE VARIABLE ONE EQUALS THE ADDRESS OF VARIABLE ZERO GOTO ONE ZERO ONE
LINE NUMBER ONE ZERO ONE CODE THE JUMP REGISTER EQUALS THE VALUE AT VARIABLE ONE GOTO ONE ONE ZERO IF THE JUMP REGISTER IS ONE GOTO ONE ZERO ZERO ZERO IF THE JUMP REGISTER IS ZERO
LINE NUMBER ONE ONE ZERO CODE PRINT ONE GOTO ONE ONE ONE
LINE NUMBER ONE ONE ONE CODE VARIABLE ONE EQUALS THE ADDRESS OF THE VALUE BEYOND VARIABLE ONE GOTO ONE ZERO ONE
LINE NUMBER ONE ZERO ZERO ZERO CODE PRINT ZERO

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