I fixed the problem!

It was an issue with my RAM OE#/WE#/CE# logic. I completely rewired it to switch from CE# to WE# controlled write cycle logic (if this even make sense, basically switched the phi2 nand-strobe from one line to the other) and everything started working fine. I think there was ...

Thanks to all of you for the inputs. Ill try to see if I can dig an ez-usb device somewhere, otherwise it will have to wait until the christmas vacation as my logic analyzer is 8 channels. I don't think I'd be able to get a high enough throughput on usb on any of my embedded devices in a timely ...

Yep, the music play right, at 50hz (timer A value).
Characters received from UART are displayed on the LCD just fine... for like 10-20 seconds.
Then as soon as 2 interrupts are triggering closeby (100 microsecs or so), it all crashes. And from sniffing the chip enable signals, it seems to just ...

Na its my copy/pasting from vim which had bad indentation, and I accidently posted while editing.

So thats my whole ISR

*=$E000
!to "isrE000.bin", plain
!cpu 65c02

cia_icr = $DC0D
uart_isr = $D302
temp = $1F
tb_flag = $20
uart_flag = $21
sid_flag = $22

int_routine
pha
phx
phy


check_timer_a
lda cia_icr ; ack int/get int data
tax
and #$01
beq check_timer_b
inc sid_flag

check ...

Hi, I've been designing and building a 1MHz WDC65c02 based system for the last month and I'm running into a seemingly irresolvable issue. If anyone has any idea, guess or insight about what might be causing this, it would be greatly appreciated.

I'm using a spare CIA (MOS 6526) to generate ...