SAME instruction, if I may express the concept in such an opaque
manner. Serious contemplation of the amazingly different functions
represented by the one assemler mnemonic LD almost gave one cause to
doubt one’s own sanity:
LD (HL),A and even
LD A, (CHL)
were sort of comprehensible, but do we have,
and if not, why not?
The ability to manipulate literal data provided another startling
contrast with most older machines. Being able to go
makes for a machine with a very friendly feel, and makes the dreaded
NOVA for which, even at assembler level, one would have to write
look really pretty silly by comparison.
Of the other points that made a strong initial impression, the only
remaining one really worthy of mention seems to be the stack: those who
have written code to organise stacks for themselves must surely be
appreciative, as we were, of this great facility being provided in the
hardware, though I do admit that this is hardly exceptional in modern
So much for the machine. It has been asserted that “All machine codes
are the same when you’ve worked out what the registers do”, and with
this thought (and a bottle of port purchased from one of the more
respectable Cambridge Colleges) to sustain us, we set about our first
night of Z80 hacking in tolerably high spirits.
It is amazing what optimism and alcohol can achieve between them. By
the time that we adjourned at about 3.00 a.m., there were clearly two
pieces of code which were approaching one another with every appearance
of being on the brink of joining together and making something
approaching a program.
Panic mounted during the succeeding days as the deadline approached
nearer. Lunchtimes and precious weekend hours were all sacrificed to
the cause, but by about day 5 one intrepid pioneer had made a
controlled landing, to general rejoicing among the onlookers.
All conceivable arms were twisted to provide manpower for the project
("Finals? You don’t need to revise for finals"). All praise is due to
those who originally landed us in the frying pan for preventing our
further descent into the fire. The program, however, got written.
Whether or not it is a great piece of software, and whether or not it
can win a competition (It did! –Ed.), the conclusion to this narrative,