source code
Yes
it's true, I really did write Ant Attack without an assembler -
and here's the proof! AA consists of a few hundred (I guess - not
all have survived) handwritten A4 sheets. This one is the code that
paralyses an ant when you jump on it. I have added the stuff in
blue to give an idea what's going on. Skip the next bit if you
already know about 'puters! The centre column holds the meat
of the program, the assembly language mnemonics, which are simply
shortened names for the assembly language instructions. LDA
for instance stands for "Load
Accumulator". For each mnemonic
there is an associated (machine) code written into the left-most
column. This list of numbers are the actual instructions that drive
the Z80, and they are represented here in hexadecimal notation (numbers
to the base 16), though the Z80 will see them eventually as binary,
lots of 0s and 1s. I
could have used a text editor and a program called an assembler
to do this - had never heard of 'em though! ;)
|
hexadecimal
|
decimal
|
binary
|
|
0
|
0
|
0000
|
|
1
|
1
|
0001
|
|
2
|
2
|
0010
|
|
|
etc...
|
|
|
8
|
8
|
1000
|
|
9
|
9
|
1001
|
|
A
|
10
|
1010
|
|
B
|
11
|
1011
|
|
C
|
12
|
1100
|
|
D
|
13
|
1101
|
|
E
|
14
|
1110
|
|
F
|
15
|
1111
|
|
CD028E
|
13435534
|
110011010000001010001110
|
Each hex digit
represents exactly 4 binary bits - nice and easy to think about compared
to the equivalent decimal, and takes up less space on the page than
the equivalent binary.
