INTRODUCTION



     Whew ! All that to solve just that first problem! Cheer up, it does
get easier. In fact, we already mentioned above that you can retrieve
the current row via "PEEK(84)". But how about the column?
     Again, we must remember that the column number might be big
enough to require two adjacent bytes (locations, memory cells, etc.).
Again, we could construct the larger number via the following:

     H2 = PEEK(85)
     H1 = PEEK(86)
     H  = H2 + 256 * H1

     Do you see the relationship between this and the POKEs? To "put
it back together," we must multiply the "high order byte" by 256
(because, remember, it is actually the number of 256's we could obtain
from the larger number) before adding it to the "low order byte."
     Again, let us summarize and simplify. The following code will
satisfy the second problem requirement for BASIC:

     V = PEEK(84)
     H = PEEK(85) + 256 * PEEK(86)

     Okay. We did it. For two languages. And if you are only interested
in BASIC, you can quit now. But if you are even a little bit curious,
stick with us. It gets better.

BASIC A +
There might be a little bit of prejudice on my part here, but I do feel
that this is the easiest language to explain to beginners. In fact, rather
than start with text, let's show the solutions:

     Problem 1.
        POKE 84,V
        DPOKE 85,H

     Problem 2.
        V = PEEK(84)
        H = DPEEK(85)

     As you can see, for the single memory cell situations, BASIC A +
functions exactly the same as the Atari and Microsoft BASICs. But for
the double-byte problems, BASIC A + has an extra statement and an
extra function, designed specifically to interface to the double-byte
"words" of the Atari's 6502 processor.
     DPOKE (Double POKE) performs exactly the equivalent of the two
POKEs required by Atari BASIC. DPEEK (Double PEEK) similarly
combines the functions of both the Atari BASIC PEEKs. And that's it.
Simple and straightforward.

Forth
I think the ease of performing the required problems in Forth will show
how tightly and neatly Forth is tied to the machine level of the