Assembly

The assembly language, also named Astrisc (For Astro RISC), is the lowest-level way to code programs for the Astro-8. This document covers how to use it, as well as best practices.

The total list of instructions can be found here

Formatting style

Astrisc is case-insensitive, meaning it does not matter if you capitalize commands or not. For style purposes, it is recommended to use lowercase when you are programming for all characters (it is easier to type and read). Programs that are compiled from another language (such as Armstrong or Yabal) will often output in UPPERCASE, which is standard practice for Astrisc that is computer-generated.

Due to the case-insensitivity, this also means variables and labels will not be seen as different with just differently capitlized letters. For example, #THISISALABEL will be seen the same as #ThisIsALabel.

Set command

Sets the specified memory location to a value during assembly, uses following format:

set <Address> <Value>

This command itself does not occupy a memory location, and following code will collapse to take it’s place.

Here command

Set the location of the HERE in memory equal to a value during assembly, uses following format:

here <Value>

This command itself does occupy a memory location.

Labels

You can use the # symbol to define a label to a location in code.

#firstlabel:
    lda 2
    add
#secondlabel:
    jmp #firstlabel

Labels are simply constants that store the address of the following instruction. For example, this is what the code above would look like without labels (I also added line numbers):

0    lda 2
1    add
2    jmp 0

In this case, #firstlabel would contain the value 0, and #secondlabel would contain the value 2.

If there is a clear section of code the label is defined for, rather than a simple jump, it is better to make that syntactically clear by indenting with a tab or 4 spaces, as in the above syntax example.

Constants

You can use the const keyword to define a constant integer variable in your code. It follows the format:

const <name> <integer>

In modern Astrisc, it is best practice to use constants and labels if at all possible, and to avoid hard-coding line numbers and such into your program.

const @xVar 5  ,define variable

lda $xVar  ,use variable
add

const @yVar 7  ,define another variable

ldib $yVar  ,use the other variable

Each use case of this variable will simply be replaced with the integer when the code is assembled. The above example will become:

0    lda 5
1    add
2    ldib 7

Comments

You can add single-line comments to your code using the comma symbol , followed by the comment contents.

Syntax

,<Comment>

Example

,This is a comment
add
ldia 5  ,This is another comment

Due to the fact the comma , character us used here, and is often used in other languages to separate values, the best way to use these is by placing the comment directly after the character like ,<comment>, and to place 2 space characters ` ` before it if there is already a command. Such as add ,Comment.

Alloc

You can use the alloc keyword to allocate an area in memory. It follows the format:

alloc <size>

Example:

alloc 5
lda 3
add

This becomes:

0    here 0
1    here 0
2    here 0
3    here 0
4    here 0
5    lda 3
6    add

The alloc simply clears that area of memory for <size> memory locations

alloc 0 would remove the command, and not place any here 0 commands.