Fix bug where A was overwritten in _uart_txb_block

If you wanted to transmit a value and then check what it was, you can do that now.
2022-03-14 22:19:19 -05:00
parent a627d38778
commit 340f43103a
1 changed files with 2 additions and 0 deletions
--- a/sw/uart.s
+++ b/sw/uart.s
@@ -17,10 +17,12 @@ _uart_txb:
        rts

 _uart_txb_block:
+        pha
        sta UART_TXB        ; Write value
@1:     lda UART_STATUS     ; Wait for status[0] to be 0
        bit #$01
        bne @1
+        pla
        rts

 _uart_rxb: