YTD 12-bit Computer

Yeahbut, aka Kyler Olsen

NOTICE: This project is still a work in progress.

It is a custom computer and instruction set architecture. It also has its own assembly language with assembler written in Python. Custom high level language currently in development.

ISA

Assembly Language

Registers

• ZR
• PC
• SP
• MP
• D0
• D1
• D2
• D3

Zero Operand Instructions

• NOP
• HLT
• BNZ
• BNA
• BNP
• BNN

One Operand Instructions

• GLA Destination Register
• GET Destination Register
• LOD Destination Register
• STR Source Register
• POP Destination Register
• PSH Source Register
• LIU Immediate Value
• LDI Immediate Value
• LDI :Label
• LIL Immediate Value

Two Operand Instructions

• LSH Destination Register Source Register
• RSH Destination Register Source Register
• INC Destination Register Source Register
• DEC Destination Register Source Register

Three Operand Instructions

• AND Destination Register Source Register A Source Register B
• OR Destination Register Source Register A Source Register B
• SUB Destination Register Source Register A Source Register B
• XOR Destination Register Source Register A Source Register B
• NOR Destination Register Source Register A Source Register B
• NAD Destination Register Source Register A Source Register B
• ADD Destination Register Source Register A Source Register B

High Level Language

WIP

About

• Paradigm: Multi-Paradigm: Procedural (Imperative), Structured
• Designer: Kyler Olsen
• Created: Mar 2024
• Typing Discipline: Static, Weak
• Platform: ytd 12-bit computer, ytd 12-bit emulator (from pytd12dk, multi-platform)
• License: MIT
• Filename extension: .ytd12c
• Compiler Implementations: pytd12dk (Python), ytd12nc (native compiler)

Lexical

Directives

Directives start with # and end at the end of a line. They are used to give additional instructions to the compiler.

Comments

Comments can either be single-line comments or multi-line comments.

Single-line comments start with // and end at the end of a line.

Multi-line comments start with /* and end with */.

pytd12dk implementation detail: Comments and their content are ultimately ignored by the lexer after they are tokenized. There are no comments in the output of the lexer.

Identifiers

Can be up to 15 characters in length, and are case sensitive. They cannot be a keyword.

Identifier ::= ID_Start ID_Continue*
ID_Start ::= <Any latin alphabet ligature or an underscore: "A"-"Z", "a"-"z", "_">
ID_Continue ::= ID_Start | <Any decimal ligature: "0"-"9">

Keywords

struct      fn          enum        static
if          else        do          while
for         break       continue    let
unsigned    int         fixed       float
True        False       None

Literals

Number Literals

number ::=  decinteger | bininteger | octinteger | hexinteger | pointfloat | exponentfloat
decinteger ::=  nonzerodigit (["_"] digit)* | "0"+ (["_"] "0")*
bininteger ::=  "0" ("b" | "B") (["_"] bindigit)+
octinteger ::=  "0" ("o" | "O") (["_"] octdigit)+
hexinteger ::=  "0" ("x" | "X") (["_"] hexdigit)+
nonzerodigit ::=  "1"..."9"
digit ::=  "0"..."9"
bindigit ::=  "0" | "1"
octdigit ::=  "0"..."7"
hexdigit ::=  digit | "a"..."f" | "A"..."F"
pointfloat    ::=  ([digitpart] fraction) | (digitpart ".")
exponentfloat ::=  (digitpart | pointfloat) exponent
digitpart     ::=  digit (["_"] digit)*
fraction      ::=  "." digitpart
exponent      ::=  ("e" | "E") ["+" | "-"] digitpart

Character Literals

Character Literals must be on one line and begin and end with '. They can only have one printable ascii character or escape code.

String Literals

String Literals must be on one line and begin and end with ". They can have a unspecified number of printable ascii characters and escape codes.

Escape Codes

Code	Meaning
\0	Null Character
\a	Alert (Beep, Bell)
\b	Backspace
\e	Escape Character
\f	Formfeed Page Break*
\n	Line Feed
\r	Return Carriage
\t	Horizontal Tab
\v	Vertical Tab*
\\	Backslash
\'	Single Quotation Mark (In char literals)
\"	Double Quotation Mark (In str literals)

Punctuation

++      --      @       $       +       -
*       /       %       ~       &       |
^       <<      >>      =       +=      -=
*=      /=      %=      &=      |=      ^=
<<=     >>=     !       &&      ||      ^^
==      !=      <       <=      >       >=
{       }       [       ]       (       )
?       .       ->      ,       ;       :

Syntax

The syntactical structure starts with a File at the root.

File

A File can contain any number of the following elements:

• directive
• struct
• enum
• function

Directive

Just a directive.

pytd12dk implementation detail: Their content is stored here for later when directive compilation occurs.

struct

A struct begins with the struct keyword. It then has its identifier followed by a comma (,) separated list enclosed in curly braces ({ and }) of structure members.

Structure Member

A structure member begins with its identifier, which may optionally be preceded with the static keyword. After a colon (:) is its data type. It may then optionally be followed by an equal sign (=) and a literal.

enum

A enum begins with the enum keyword. It then has its identifier followed by a comma (,) separated list enclosed in curly braces ({ and }) of enum members.

Enum Member

An enum member begins with its identifier. It can then optionally be followed by an equal sign (=) and a number literal.

Function

A function begins with the fn keyword. It then has its identifier followed by a comma (,) separated list enclosed in parentheses (( and )) of function parameters. After that is an arrow (->) followed by a data type denoting the function's return type. After that is a list enclosed in curly braces ({ and }) of statements.

Function Parameter

A function parameter begins with its identifier, followed by a colon (:) and its data type. It may then optionally be followed by an equal sign (=) and a literal.

If Statement

An if statement begins with the if keyword, followed by its condition, an expression enclosed in parentheses (( and )), then a single statement or a list enclosed in curly braces ({ and }) of statements. It may then optionally be followed by an else block.

Do Loop

A do loop begins with the do keyword, followed by a single statement or a list enclosed in curly braces ({ and }) of statements. It is then followed with the while keyword, then by its condition, an expression enclosed in parentheses (( and )). It is then followed by a single statement or another list enclosed in curly braces ({ and }) of statements. Finally the do loop may optionally be followed by an else block.

While Loop

A while loop begins with the while keyword, followed by its condition, an expression enclosed in parentheses (( and )), then a single statement or a list enclosed in curly braces ({ and }) of statements. It may then optionally be followed by an else block.

For Loop

A for loop begins with the for keyword, followed by three expressions enclosed in parentheses (( and )), separated by semicolons (;). The first expression is a pre-loop expression, the second is its condition which is a normal expression, and the last is its post-loop expression which is another normal expression. It is ended with a single statement or a list enclosed in curly braces ({ and }) of statements. It may then optionally be followed by an else block.

Pre-Loop Expression

A pre-loop expression can be a normal expression or a special variable definition. It starts its identifier, then a colon (:) is its data type, then an equal sign (=) followed by an expression.

Else Block

An else block begins with the else keyword, followed by a single statement or a list enclosed in curly braces ({ and }) of statements.

Let Statement

A let statement begins with the let keyword, which may optionally be preceded with the static keyword. It then has its identifier, followed by a colon (:) and its data type. It may then optionally be followed by an equal sign (=) and an expression. It must then be finished with a semicolon (;).

Expressions

Unary Expression

A unary expression is made up of one expression and one unary operator. The operator may come before or after the expression.

Binary Expression

A binary expression is made up of one expression, then one binary operator, then another expression.

Ternary Expression

A ternary expression is made up of one expression which is the condition, then a question mark (?) followed by two expressions separated by a colon (:).

Function Call

A function call starts with an identifier followed by a comma (,) separated list enclosed in parentheses (( and )) of function arguments.

Function Argument

A function argument is an expression that may optionally be preceded by an identifier which is immediately followed by an equal sign (=).

Enclosed Expression

An enclosed expression is simply an expression enclosed in parentheses (( and )).

Operator

Here are all operators and their types and names in order of operator precedence.

Operator	Type	Name
@	Unary (Prefix)	Address of Operator
$	Unary (Prefix)	Dereference Operator
~	Unary (Prefix)	Bitwise NOT Operator
--	Unary (Postfix)	Postfix Decrement Operator
++	Unary (Postfix)	Postfix Increment Operator
--	Unary (Prefix)	Prefix Decrement Operator
++	Unary (Prefix)	Prefix Increment Operator
-	Unary (Prefix)	Negate Operator
!	Unary (Prefix)	Boolean NOT Operator
.	Binary	Member of Operator
>>	Binary	Right Shift Operator
<<	Binary	Left Shift Operator
^	Binary	Bitwise XOR Operator
|	Binary	Bitwise OR Operator
&	Binary	Bitwise AND Operator
%	Binary	Modulus Operator
/	Binary	Division Operator
*	Binary	Multiplication Operator
-	Binary	Subtraction Operator
+	Binary	Addition Operator
>=	Binary	Greater or Equal to Than Operator
>	Binary	Greater Than Operator
<=	Binary	Less or Equal to Than Operator
<	Binary	Less Than Operator
!=	Binary	Inequality Comparison Operator
==	Binary	Equality Comparison Operator
^^	Binary	Boolean XOR Operator
||	Binary	Boolean OR Operator
&&	Binary	Boolean AND Operator
? :	Ternary	Ternary Conditional Operator
>>=	Binary	Right Shift Assignment Operator
<<=	Binary	Left Shift Assignment Operator
^=	Binary	Bitwise XOR Assignment Operator
|=	Binary	Bitwise OR Assignment Operator
&=	Binary	Bitwise AND Assignment Operator
%=	Binary	Modulus Assignment Operator
/=	Binary	Division Assignment Operator
*=	Binary	Multiplication Assignment Operator
-=	Binary	Subtraction Assignment Operator
+=	Binary	Addition Assignment Operator
=	Binary	Assignment Operator

Literal

A literal is just simply the content of the literal. There are three types of literals:

• Number Literal
• Character Literal
• String Literal

Identifier

A identifier is just simply the name of the identifier.

Data Type

A data type is made up of an identifier or default data type, and may optionally be preceded by an at symbol (@).

Default Data Types

There are four default data types represented by the following keywords:

• unsigned
• int
• fixed
• float

Statement

A statement is made up of an expression followed by a semicolon (;), a let statement, a loop statement, or a nestable code block.

Nestable Code Block

There are four nestable code blocks:

• if statement
• do loop
• while loop
• for loop

Loop Statement

A loop statement are either the keyword continue or break followed by a semicolon (;).

Semantics

pytd12dk

pytd12dk (Python ytd 12-bit development kit) is a tool set written in Python to assist in developing software for the ytd 12-bit computer. It includes a compiler, assembler with linker, and emulator.

NOTICE: pytd12dk requires Python version 3.12 (or higher).

Compiler

The first part of the tool kit is the compiler. It is currently unfinished and can not yet produce an executable.

Running the following command we can get the arguments for the compiler python -m pytd12dk cm -h:

usage: __main__.py cm [-h] [-t TOKEN_FILE] [-x SYNTAX_FILE] input_file

positional arguments:
  input_file

options:
  -h, --help            show this help message and exit
  -t TOKEN_FILE, --token_file TOKEN_FILE
  -x SYNTAX_FILE, --syntax_file SYNTAX_FILE

The only required positional argument is input_file. This is the source code file to be compiled.

The optional argument --token_file is a text file output which contains debug information from the output of the lexer. It is a list of the tokens parsed from the source file and their lexical types.

The optional argument --syntax_file is a text file output which contains debug information from the output of the syntactical analyzer. It is a text representation of the syntax tree.

Additional optional arguments for semantical debug info, object file, and executable file will be added.

Assembler

The second part of the tool kit is the assembler. Included with the assembler is a simple linker.

Running the following command we can get the arguments for the compiler python -m pytd12dk am -h:

usage: __main__.py am [-h] [-o OUTPUT_FILE] [-l LABELS_FILE] [-x HEX_FILE] input_file

positional arguments:
  input_file

options:
  -h, --help            show this help message and exit
  -o OUTPUT_FILE, --output_file OUTPUT_FILE
  -l LABELS_FILE, --labels_file LABELS_FILE
  -x HEX_FILE, --hex_file HEX_FILE

The only required positional argument is input_file. This is the assembly code file to be assembled.

The optional argument --labels_file is a text file output which contains a list of the labels found and their address locations in the executable.

The optional argument --hex_file is a text file output which contains the generated machine code in hexadecimal representation.

The optional argument --output_file is a binary file output which contains the generated machine code which can directly be executed by the emulator.

Emulator

The second part of the tool kit is the assembler. Included with the assembler is a simple linker.

Running the following command we can get the arguments for the compiler python -m pytd12dk em -h:

usage: __main__.py em [-h] [-m {tty}] [-v] [-s] [-c CLOCK] rom_file

positional arguments:
  rom_file

options:
  -h, --help            show this help message and exit
  -m {tty}, --machine {tty}
  -v, --verbose
  -s, --step
  -c CLOCK, --clock CLOCK

The only required positional argument is rom_file. This is the executable binary generated by the assembler or compiler.

The optional argument --machine allows for the selection of a pre-configured virtual machine. Later in the section [Pre-configured VMs] are a list of included machine(s). The default selection is tty.

The optional argument --verbose turns on printing the current program address, the value at the address, the interpreted instruction, and each register and their current values every clock cycle.

The optional argument --step turns on waiting for user input between each clock cycle. This disables any set or default value of the option --clock, making it essentially zero.

The optional argument --clock sets the time between each clock cycle in thousandths of a second. The default value is 100 (one tenth of a second).

Pre-configured VMs.

Here are the pre-configured virtual machine(s) included with pytd12dk.

tty

The machine tty includes a tty IO device.

Writing to address 0x7FD outputs a signed integer.

Writing to address 0x7FE outputs an unsigned integer.

Writing to address 0x7FF outputs an ASCII/UTF-8 character.

Reading from address 0x7FF inputs an ASCII/UTF-8 character.

ytd12nc

ytd12nc (ytd 12-bit native compiler) is a compiler and assembler with linker written in the native high-level programming language and assembly language to compile software for the ytd 12-bit computer natively.

Currently development of ytd12nc has not yet started.