# little person computer

the little person computer is a model to learn about {computer architecture}

# architecture

is uses the decimal system, with words of three-digits each.

it has ten instructions and 100 memory addresses.

# example programs

written in the corresponding assembly language.

as part of the {s-camino} practice.

## multiplication of two numbers

### no labels

pure assembler version, no labels.

* 15 is the address for the result
* 16 is the address for 'a'
* 17 is the addres for 'b'

```
        INP
        STA 16
        INP
        STA 17
        BRZ 11
        LDA 16
        ADD 15
        STA 15
        LDA 17
        SUB 14
        BRA 3
        LDA 15
        OUT
        HLT
        DAT 1
        DAT 0
        DAT 0
        DAT 0
```

### with labels

the same behavior as above, but using labels for easier programming and reading

```
inputs  INP
        STA a
        INP
loop    STA b
        BRZ print // finish if b is 0
        LDA a
        ADD result
        STA result
        LDA b
        SUB one
        BRA loop
print   LDA result
        OUT
        HLT
one     DAT 1
result  DAT 0
a       DAT 0
b       DAT 0
```

# external links

=> https://teachcomputerscience.com/little-man-computer/ little man computer
=> https://teachcomputerscience.com/lmc-instruction-set/ the lmc instruction set
=> https://www.peterhigginson.co.uk/lmc/ little man computer - cpu simulator