From 0d6c7922822d1f8c78f8a58daea434ad625fd37c Mon Sep 17 00:00:00 2001
From: Wayne Warthen <wwarthen@gmail.com>
Date: Sat, 13 Feb 2021 17:14:59 -0800
Subject: [PATCH] Z280 Tweaks

- Interrupt routines that change the Z280 I/O page register now save and restore the original value.
---
 Source/HBIOS/hbios.asm | 10 ++++++----
 Source/HBIOS/z2u.asm   | 34 +++++++++++++++++++++++++++++-----
 Source/ver.inc         |  2 +-
 Source/ver.lib         |  2 +-
 4 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 458973df..5c7828f9 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -3565,9 +3565,11 @@ Z280_TIMINT:
 	; CALL PRIMARY TIMER LOGIC
 	CALL	HB_TIMINT
 ;
-	; SELECT I/O PAGE $FE
-	LD	L,$FE			; COUNTER/TIMER I/O PAGE
+	; SELECT I/O PAGE $FE (SAVING PREVIOUS VALUE)
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
+	.DB	$ED,$66			; LDCTL HL,(C) ; GET CURRENT I/O PAGE
+	PUSH	HL			; SAVE IT
+	LD	L,$FE			; NEW COUNTER/TIMER I/O PAGE
 	.DB	$ED,$6E			; LDCTL	(C),HL
 ;
 	; CLEAR END OF COUNT CONDITION TO RESET INTERRUPT
@@ -3575,9 +3577,9 @@ Z280_TIMINT:
 	RES	1,A			; CLEAR CC
 	OUT	(Z280_CT0_CMDST),A	; SET C/T 0
 ;
-	; RESTORE I/O PAGE TO $00
-	LD	L,$00			; NORMAL I/O REG IS $00
+	; RESTORE I/O PAGE
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
+	POP	HL			; RECOVER ORIGINAL I/O PAGE
 	.DB	$ED,$6E			; LDCTL	(C),HL
 ;
 	; RESTORE REGISTERS
diff --git a/Source/HBIOS/z2u.asm b/Source/HBIOS/z2u.asm
index 040ab5cd..40032c1b 100644
--- a/Source/HBIOS/z2u.asm
+++ b/Source/HBIOS/z2u.asm
@@ -171,9 +171,11 @@ Z2U_INT:
 	PUSH	DE
 	PUSH	HL
 ;
-	; START BY SELECTING I/O PAGE $FE
-	LD	L,$FE			; Z280 UART REGISTERS AT I/O PAGE $FE
+	; START BY SELECTING I/O PAGE $FE (SAVING PREVIOUS VALUE)
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
+	.DB	$ED,$66			; LDCTL HL,(C) ; GET CURRENT I/O PAGE
+	PUSH	HL			; SAVE IT
+	LD	L,$FE			; NEW COUNTER/TIMER I/O PAGE
 	.DB	$ED,$6E			; LDCTL	(C),HL
 ;
 	; CHECK TO SEE IF SOMETHING IS ACTUALLY THERE
@@ -228,9 +230,9 @@ Z2U_INTRCV3:
 	JR	NZ,Z2U_INTRCV1
 ;
 Z2U_INTRCV4:
-	; RESTORE I/O PAGE TO $00
-	LD	L,$00			; NORMAL I/O REG IS $00
+	; RESTORE I/O PAGE
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
+	POP	HL			; RECOVER ORIGINAL I/O PAGE
 	.DB	$ED,$6E			; LDCTL	(C),HL
 ;
 	; RESTORE REGISTERS
@@ -351,7 +353,6 @@ Z2U_OUT:
 #IF (INTMODE < 3)
 ;
 Z2U_IST:
-;
 	; START BY SELECTING I/O PAGE $FE
 	LD	L,$FE			; Z280 UART REGISTERS AT I/O PAGE $FE
 	LD	C,Z280_IOPR		; REG C POINTS TO I/O PAGE REGISTER
@@ -368,6 +369,7 @@ Z2U_IST:
 ;
 	OR	A			; SET FLAGS
 	JP	Z,CIO_IDLE		; NOT READY, RETURN VIA IDLE PROCESSING
+	
 	RET
 ;
 #ELSE
@@ -421,6 +423,7 @@ Z2U_INITDEV:
 Z2U_INITSAFE:
 	LD	A,%11000010		; 8N0, DIV 16, NO C/T
 	LD	(Z2U_CFGREG),A		; SAVE IT
+	LD	HL,1			; C/T DIV 1
 	JR	Z2U_INITDEV8		; DO IT
 ;
 Z2U_INITDEVX:
@@ -436,6 +439,27 @@ Z2U_INITDEVX:
 ;
 Z2U_INITDEV1:
 	LD	(Z2U_NEWCFG),DE		; SAVE NEW CONFIG
+	
+;
+; HACK FOR TESTING!!!
+;
+#IF FALSE
+	;LD	A,%11000000		; 8N0, DIV 1, NO C/T
+	LD	A,%11000010		; 8N0, DIV 16, NO C/T
+	;LD	A,%11000100		; 8N0, DIV 32, NO C/T
+	;LD	A,%11000110		; 8N0, DIV 64, NO C/T
+	LD	(Z2U_CFGREG),A		; SAVE UART CONFIG VALUE
+	;LD	HL,1			; 24MHZ / 8 / 1
+	LD	HL,2			; 24MHZ / 8 / 2
+	;LD	HL,3			; 24MHZ / 8 / 5
+	;LD	HL,15			; 24MHZ / 8 / 15
+	;LD	HL,26			; 24MHZ / 8 / 26 = 115384 BAUD (~115200)
+	;LD	HL,52			; 24MHZ / 8 / 52 = 57692 BAUD (~57600)
+	JP	Z2U_INITDEV8		; SKIP AHEAD TO IMPLMENT IT
+#ENDIF
+;
+;
+;
 	LD	A,D			; HIWORD OF CONFIG
 	AND	$1F			; ISOLATE BAUD RATE
 	PUSH	AF
diff --git a/Source/ver.inc b/Source/ver.inc
index a06edde1..cd26a4ba 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	1
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1.1-pre.45"
+#DEFINE BIOSVER	"3.1.1-pre.46"
diff --git a/Source/ver.lib b/Source/ver.lib
index d9f12158..0d0daaa7 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	1
 rtp	equ	0
 biosver	macro
-	db	"3.1.1-pre.45"
+	db	"3.1.1-pre.46"
 	endm