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Forums > C64 Coding > Reading RAM under ROM at $e000 doesn't work
2014-02-19 15:44
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.
2014-02-19 15:47
JackAsser

Registered: Jun 2002
Posts: 2038
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.
2014-02-19 15:53
algorithm

Registered: May 2002
Posts: 707
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 :-)
2014-02-19 17:55
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. :-/
2014-02-19 17:59
Zyron

Registered: Jan 2002
Posts: 2381
So what do you get in $e000?
2014-02-19 17:59
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.
2014-02-19 17:59
chatGPZ

Registered: Dec 2001
Posts: 11523
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 =)
2014-02-19 18:15
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 :)
2014-02-19 18:16
Oswald

Registered: Apr 2002
Posts: 5127
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.
2014-02-19 18:17
enthusi

Registered: May 2004
Posts: 679
+ cc65 is no assembler
2014-02-19 18:21
Peabrain
Account closed

Registered: Feb 2003
Posts: 24
yes. but i use cc65 for my c code and as linker for my assembler stuff.
 
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