From 2c432b3fc179d707397b8b015edbc8075e97de04 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Sun, 30 Jan 2022 22:29:33 -0500
Subject: [PATCH] command-L toggles local/online mode.

---
 vt100.key.S   | 23 ++++++++++++++++++++---
 vt100.modem.S | 23 +++++++++++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/vt100.key.S b/vt100.key.S
index 3f20b66..082d5e4 100644
--- a/vt100.key.S
+++ b/vt100.key.S
@@ -112,6 +112,10 @@ command ; or option
 	beq :bs
 	cmp #$0d
 	beq :lf
+	cmp #'l'
+	beq :local
+	cmp #'L'
+	beq :local
 
 	cmp #:MIN
 	blt :rts
@@ -126,14 +130,27 @@ command ; or option
 :rts	rts
 
 
-:MIN	equ 49
-:MAX	equ 52
-
 :bs	lda #$08
 	jmp dispatch ; 
 :lf	lda #$0a
 	jmp dispatch
 
+	ext enable_modem,disable_modem
+:local
+	bit LOCAL
+	bmi :online
+	lda #$80
+	sta LOCAL
+	jmp disable_modem
+
+:online
+	stz LOCAL
+	jmp enable_modem
+
+
+:MIN	equ 49
+:MAX	equ 52
+
 
 :table
 	dw pf1	; 1
diff --git a/vt100.modem.S b/vt100.modem.S
index a7129ea..186e21a 100644
--- a/vt100.modem.S
+++ b/vt100.modem.S
@@ -31,6 +31,7 @@ SerFlag		equ $e10104 ;
 * see IIgs TN #18 - Do-It-Yourself SCC Access
 
 init_modem ent
+enable_modem ent
 *	sep #$30
 
 	php
@@ -89,6 +90,28 @@ init_modem ent
 	db 9,%00_0_0_1_0_1_0 ; master interrupts enabled.
 	db -1,-1
 
+
+disable_modem ent
+* local mode
+	mx %11
+	php
+	sei
+
+	lda SCCBREG ; sync access
+	lda #9
+	sta SCCBREG
+	lda #%01_0_1_0_0_0_1 ; reset channel B.
+	sta SCCBREG
+
+	stz read_q_head
+	stz read_q_tail
+	stz write_q_head
+	stz write_q_tail
+
+	plp
+	rts
+
+
 write_modem_sync ent
 	mx %11
 * a: byte to send