> When I started programming in the 80's, the let statement seemed
> pretty stupid... commodore code...  copy the value of the variable
> to a register, copy the value you want to set into another register,
> sys a kernel routine to copy the value to it, then sys another routine=20

One the most useful books I bought when programming the C64
was one that I still refer to from time to time. "What's Really Inside
The Commodore 64" by Milton Bathurst, 1983, is a commented
disassembly of the machine language of the operating system (I also
have a companion book, The Anatomy Of The 1541 Disk Drive,
also a commented disassembly).

A really cool thing about the C64 was that it had shadow RAM at
the same address as the ROMs, so you could make a copy of the
O/S in RAM and edit it. This included devising new instructions/
tokens for BASIC and writing your own ML routines to process
them, or alter BASIC or KERNEL functions. I had a lot of fun
with it, as well as valuable learning as to how ML works. They
packed a lot into 2 x 8k and to see it explained line by line was
just great

FYI, on the C64 LET is detected and processed as a token but
with the same routine that simply processes the variable following
as if there was no LET

$A7F1  BCC $A804 ;perform LET
....
$A804  JMP $A9A5 ;execute command LET
....
$A9A5  JSR $B08B ;gather name and get pointer to variable

etc

Ahhh, that takes me back

Joe
--=20
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