# Mistakes

## Don't design opcodes in your head

You WILL screw up and your binary encodings WILL overlap.
You definitely need some tool to design instruction opcodes
for anything more complicated than just 1-byte instructions.

Turned out this mistake propogates further when implementing
assembler.

## Load/store instructions MUST be able to use register as address

I have no idea how we didn't notice this mistake.
I guess it is not too bad for a CPU with 16 bytes of memory,
but for something bigger it is unacceptable.

## Jump instructions need more love

Jumping 3 instructions back and 7 forward is too limiting.
Seriously, that's stupid.

Also, in my current design, jumping offset of 0 will
move CPU to an infinite loop.

## Implementing assembler with regex is not fancy

It is probably easier to implement than writing proper
lexer/parser, but error reporting can be weird.

## Two registers are really not enough

Just imagine, you are trying to write a loop, you use
`R1` as your index variable and `R0` for your loop condition.
Now you have already ran out of registers and you didn't even
start writing loop body!