| |
Peabrain
Account closed
Registered: Feb 2003
Posts: 24 |
Reading RAM under ROM at $e000 doesn't work
hello,
i try to read the memory under the kernal rom, but it doesn't work.
my $01 config is $35. so the processor should read it.
if i use another config my program crashed. so what could i do?
please help.
thanks. |
|
| |
JackAsser
Registered: Jun 2002
Posts: 2014 |
That should work. Did it crash? Perhaps you're using IRQ on kernel-vector $0314/15? If you set $01 to #$35 then the HW IRQ-vector at $fffe/ffff will also be seen as RAM by the CPU hence point to oblivion unless you've explicitly set it. |
| |
algorithm
Registered: May 2002
Posts: 705 |
Did you check the data direction port register at $00? By default if you have left this location as it is, then this should not be a problem.
and i know you may have done this already but check that it is #$35 instead of $35 :-) |
| |
Peabrain
Account closed
Registered: Feb 2003
Posts: 24 |
i use the hw irq vector. and it don't crash if #$35 in $01. in $00 is #$2f.
if:
$e000 -> $00
and i do
lda $e000
sta $e000
then:
$e000 -> ?? but not $00
that my problem. :-/ |
| |
Zyron
Registered: Jan 2002
Posts: 2381 |
So what do you get in $e000? |
| |
Peabrain
Account closed
Registered: Feb 2003
Posts: 24 |
ok, i got the problem. thats happen, if you use cc65 and assembler.
it seems to be that the cc65 overwrites my value in $01.
thats bad.
if i write:
ldx $01
lda #$35
sta $01
lda $e000
sta $e000
stx $01
this is running.
damned. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11386 |
you really should post a snippet of code that doesnt work... else it is shooting in the dark :=) it must be some stupid little trival thing that you are overlooking =) |
| |
Peabrain
Account closed
Registered: Feb 2003
Posts: 24 |
thats a little bit too huge. :D
but i checked the cc65 specs. the normal projectseting are with kernelroms enabled.
and i must visit the documentation. its not a problem of my code :) |
| |
Oswald
Registered: Apr 2002
Posts: 5094 |
if you dont have high expectations from an assembler other than compiling your lda sta code, maybe macro a bit, and generate some tables, then you better use 64tass. cc65 is an overcomplicated bloated shit if you are not close to a genius. |
| |
enthusi
Registered: May 2004
Posts: 677 |
+ cc65 is no assembler |
| |
Peabrain
Account closed
Registered: Feb 2003
Posts: 24 |
yes. but i use cc65 for my c code and as linker for my assembler stuff. |
| |
Mace
Registered: May 2002
Posts: 1799 |
You don't have to post the enitre code, just the relevant parts.
If you don't put effort in it, don't expect us to solve the problem. |
| |
Oswald
Registered: Apr 2002
Posts: 5094 |
then bad news.. probably you got the complicated memory / linker / whatever config wrong somewhere.
in 64tass sei lda #$35 sta $01 just works. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:cc65 is an overcomplicated bloated shit if you are not close to a genius.
bullshit. only because the only thing you can deal with are trivial onefile assemblers, more featured ones arent made for geniuses. or well, maybe they are, and thats why certain people struggle so much with them :o)
peabrain: if you are using a C/asm combination, then make sure to understand the runtime environment - which has kernal enabled and basic disabled and kernal irq running. if you need to modify $01 to access ram under kernal, you should disable interrupts while the kernal is disabled (else it will crash) |
| |
Oswald
Registered: Apr 2002
Posts: 5094 |
how about checking what cc65 actually assembled? maybe its a totally different adress there.
"hats happen, if you use cc65 and assembler. it seems to be that the cc65 overwrites my value in $01."
and from this its clear peabrain doesnt really understand whats going on in cc65, perhaps not for the average coder if even ROM mapping is problematic... I think its still overcomplicated for the average c64 project. I know guys like ninja can really use it well, but definitly not for me! |
| |
chatGPZ
Registered: Dec 2001
Posts: 11386 |
ninja never used cc65 at all =) don't mix up cc65 (the c-compiler) and ca65 (the assembler).
doing a mixed asm and C project isnt trivial and not for the average coder in any case, any platform, and using any compiler. you definately need to know some stuff about the compiler internals and its runtime environment in such projects - but thats just natural.
that said, it really isnt all that complicated either - and it is documented as well. as an example on accessing the ram under kernal, look at the default "extended memory" driver source for c64 (which does just that). |
| |
Beastifire
Account closed
Registered: Mar 2013
Posts: 40 |
I guess it's a bit of a general problem in modern computing - to have so many layers of complexity that problems get hard to debug. With today's cross-platform development systems, these problems were bound to enter our scene too. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11386 |
except this problem has nothing to do with all that. the exact same problem exists when doing the same thing using a native compiler on a PET. |
