From b182a53dfae595e4ce774111a24275cb3c9ed16a Mon Sep 17 00:00:00 2001
From: frankmilliron <34376619+frankmilliron@users.noreply.github.com>
Date: Mon, 17 Jul 2023 08:11:30 -0700
Subject: [PATCH] The Cricket!: fix hang on Total Replay (#19)

* The Cricket!: fix hang on Total Replay

The Cricket reset command sends Total Replay into an endless loop when launched, presumably because of an interrupt situation (TR just does RTI on an interrupt). Toggling the COMMAND and CONTROL settings seems to allow TR to function properly, while also allowing the Cricket initialization code to silence any playing notes.

* The Cricket!: Reset Cricket before probing

Finds the Cricket every single time this way. Occasionally the driver would miss finding it due to it being in a wait state. Sending a reset first fixes that.

* The Cricket!: make sure registers are toggled for TR
---
 clocks/cricket/cricket.system.s | 52 +++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 15 deletions(-)

diff --git a/clocks/cricket/cricket.system.s b/clocks/cricket/cricket.system.s
index 3bf9ecb..491487d 100644
--- a/clocks/cricket/cricket.system.s
+++ b/clocks/cricket/cricket.system.s
@@ -77,13 +77,17 @@ ssc_not_found:
 init_ssc:
         php
         sei
+        lda     COMMAND         ; save status of SSC registers
+        sta     saved_command
+        lda     CONTROL
+        sta     saved_control
 
-        ;; Reset SSC
-        sta     KBDSTRB         ; Port 2 DSR line connected to KBDSTRB
-        lda     #0
-        sta     COMMAND         ; hardware reset all Port 2 ACIA registers
-        sta     CONTROL
-        sta     STATUS
+        ;; Reset the Cricket (stops any playing notes & ensures Cricket is listening)
+        jsr     restore_cmd_ctl ; have to change registers for this to work
+        jsr     reset_cricket
+        jsr     restore_cmd_ctl
+        jsr     reset_cricket   ; does it twice in original Cricket driver
+        jsr     restore_cmd_ctl
 
         ;; Configure SSC
         lda     #%00001011      ; no parity/echo/interrupts, RTS low, DTR low
@@ -91,15 +95,6 @@ init_ssc:
         lda     #%10011110      ; 9600 baud, 8 data bits, 2 stop bits
         sta     CONTROL
 
-        ;; Reset Cricket
-        jsr     readbyte        ; done on original disk
-        lda     #HI(ASCII_CR)   ; two carriage returns
-        jsr     sendbyte
-        lda     #HI(ASCII_CR)
-        jsr     sendbyte
-        lda     #HI('!')        ; Reset Cricket (everything but time/date)
-        jsr     sendbyte
-
         ;; Read Cricket ID code: 00 ($00)
         lda     #0
         jsr     sendbyte
@@ -126,10 +121,12 @@ digit:  cmp     #HI('0')          ; < '0' ?
         bcc     :-
 
 cricket_found:
+        jsr     restore_cmd_ctl
         plp
         jmp     install_driver
 
 cricket_not_found:
+        jsr     restore_cmd_ctl
         plp
         ;; fall through...
 
@@ -145,6 +142,31 @@ not_found:
 
         sec                     ; failure
         rts
+
+reset_cricket:
+        lda     #%00001011      ; no parity/echo/interrupts, RTS low, DTR low
+        sta     COMMAND
+        lda     #%10011110      ; 9600 baud, 8 data bits, 2 stop bits
+        sta     CONTROL
+        
+        jsr     readbyte        ; done on original disk
+        lda     #HI(ASCII_CR)   ; two carriage returns
+        jsr     sendbyte
+        lda     #HI(ASCII_CR)
+        jsr     sendbyte
+        lda     #HI('!')        ; Reset Cricket (everything but time/date)
+        jsr     sendbyte
+        rts
+
+restore_cmd_ctl:
+        lda     saved_control
+        sta     CONTROL
+        lda     saved_command
+        sta     COMMAND
+        rts
+
+saved_command:  .byte   0
+saved_control:  .byte   0
 .endproc
 
         ;; Write byte in A