4 Aug
2001
4 Aug
'01
12:01 a.m.
It was thus said that the Great "Fred Cisin (XenoSoft)" once stated:
On 4 Aug 2001, Iggy Drougge wrote:
PUSH is a good way to do it, BUT, ...
To clear ALL memory, the PUSH instruction must be at location 0 (at least
by the end of the program). Otherwise, the program code will be zero'd
out before it is done.
It doesn't have to be at 0, but it does have to be the last executable
instruction other than NOP (which is $00).
Here is
a little puzzle to test your readers' 8080 machine ingenuity:
"Imagine you possess an 8080 with 64K bytes of read/write memory
which you want to clear. Write a program that sets all 65536 bytes
to zero."
Seemed like a piece of cake until it dawned upon me that the
program has got
to be stored somewhere. =/ Can you do it WITHOUT self-modifying code?
Yes. 8-)
-spc (It only took me two hours because I've never programed the 8080/Z80
before ... )