Hi,
I started a new project and now I'm stuck. I have a minimal 6502A System with 2kbyte RAM and 2kbyte ROM and a CDP65C51AE4. Everything uses a single 1.834MHz clock. "Hello World!!" after RESET works, but it seams the ACIA never receives a character. I already replaced the CDP65C51EA4 but nothing changed. I suspect a most stupid error. I have now the following minimal code to test my system
Code:
ACIA1 = $c090
ACIA1dat = ACIA1 + 0
ACIA1sta = ACIA1 + 1
ACIA1cmd = ACIA1 + 2
ACIA1ctl = ACIA1 + 3
*=$FF00
reset
ldy #0
wait
iny
bne wait
sty $0
sty $1
lda #$1F ; 19.2K/8/1
sta ACIA1ctl ; control reg
lda #$0B ; N parity/echo off/rx int off/ dtr active low
sta ACIA1cmd ; command reg
inc $0
main
ldx #0
MAINL
lda ACIA1sta ; serial port status
and #$10 ; is tx buffer empty
beq MAINL ; no
inc $0
lda hello,x
beq MAINC
sta ACIA1dat ; put character to Port
inx
bne MAINL
MAINC
WAITC
inc $0
LDA ACIA1sta ; Serial Port Status
AND #$08 ; Is RCVR Full
BEQ WAITC
inc $1
lda ACIA1dat
sta ACIA1dat
jmp main
hello .text "Hello World!!"
.byte $0d, $0a, $00
*=$FFF8
nmi: rti
irq: rti
.byte <NMI ;NMI VECTOR
.byte >NMI
.byte <RESET ;RESET VECTOR
.byte >RESET
.byte <IRQ ;IRQ VECTOR
.byte >IRQ
It prints "Hello World!!" <CR> <LF> and waits for a input character and then just prints the initial message again. Location $1 is not incremented (the RAM is a DP-RAM so I can look into it from the other side). Any ideas what I'm missing?
Regards
Peter
EDIT: I FORGOT TO UNCHECK RTS/CTS FLOW CONTROL IN THE TERMINAL EMULATION PROGRAM I USED
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