From e8fa4a2d95b9f88b38d53ed77006931154561247 Mon Sep 17 00:00:00 2001
From: William Moore <caranmegil@gmail.com>
Date: Fri, 5 Jan 2024 00:22:07 -0600
Subject: [PATCH] Intial work on a FORTH interpreter

---
 src/1802mc/blinkqslowwithescape.asm | 64 ++++++++++++++++---
 src/z80/forth.asm                   | 95 +++++++++++++++++++++++++++++
 2 files changed, 149 insertions(+), 10 deletions(-)
 create mode 100644 src/z80/forth.asm

diff --git a/src/1802mc/blinkqslowwithescape.asm b/src/1802mc/blinkqslowwithescape.asm
index 8aa4140..d725fd2 100644
--- a/src/1802mc/blinkqslowwithescape.asm
+++ b/src/1802mc/blinkqslowwithescape.asm
@@ -14,14 +14,46 @@
 ; You should have received a copy of the GNU General Public License
 ; along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-R1	EQU	1
-R2	EQU	2
-R7	EQU 7
+R0	EQU	$00
+R1	EQU	$01
+R2	EQU	$02
+R3	EQU	$03
+R4	EQU	$04
+R5	EQU	$05
+R7	EQU	$07
+RE	EQU	$0D
+
+STACK   EQU 7F6FH
+CALL    EQU 8ADBH
+RETURN  EQU 8AEDH
+
+MON_INPUT   EQU 8005H
+MON_OUTSTR  EQU 8526H
+
+	CPU 1802
+	; ORG $0000
+
+  ; Setup code to initialize the stack and SCRT registers
+  ; SETUP R2 (Stack)
+  LDI  HIGH STACK
+  PHI  R2
+  LDI  LOW STACK
+  PLO  R2  ;STACK = 7F6FH
+  SEX  R2  ;X = 2
+
+  ; SETUP R4 (CALL PC)
+  LDI  HIGH CALL
+  PHI  R4
+  LDI  LOW CALL
+  PLO  R4  ;R4 = PC FOR CALL SUBROUTINE
+
+  LDI  HIGH RETURN
+  PHI  R5
+  LDI  LOW RETURN
+  PLO  R5  ;R5 = PC FOR RETURN SUBROUTINE
 
-	ORG 0000H
-BEGIN
 	SEQ		; announce running
-	SEX R7
+
 INKEY
 	BN4 INKEY
 	REQ
@@ -44,11 +76,23 @@ DECR
 
 DONE
 	REQ
+	; LOAD R7, NullByte
+  ; SEP  R4
+  ; DW   MON_OUTSTR
 	LOAD R7, NOLED
 	OUT 4
-	SEP R1
-
-ALLLED BYTE 255
-NOLED BYTE 0
+	LOAD R7, BYETXT
+  SEP  R4
+  DW   MON_OUTSTR
+  LDI $8B
+  PHI R0
+  LDI $5E
+  PLO R0
+  SEX R0
+  SEP R0 
 
+ALLLED	BYTE $FF
+NOLED	BYTE	0
+BYETXT	BYTE	"$", 0
+NullByte	BYTE	0
 	END
diff --git a/src/z80/forth.asm b/src/z80/forth.asm
new file mode 100644
index 0000000..2187eab
--- /dev/null
+++ b/src/z80/forth.asm
@@ -0,0 +1,95 @@
+; forth.asm - a TIL implementation of FORTH for Z80
+; Copyright (C) 2023  William R. Moore
+;
+; This program is free software: you can redistribute it and/or modify
+; it under the terms of the GNU General Public License as published by
+; the Free Software Foundation, either version 3 of the License, or
+; (at your option) any later version.
+;
+; This program is distributed in the hope that it will be useful,
+; but WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+; GNU General Public License for more details.
+;
+; You should have received a copy of the GNU General Public License
+; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+STACK	EQU	2	; stack pointer
+PC	EQU	3	; program counter
+CALLR	EQU	4	; call register
+RETR	EQU	5	; return register
+TXTPTR	EQU	7	; text pointer
+INBUF	EQU	8	; Input line buffer pointer register.
+; ; 	TIL registers
+IP	EQU	10	; Instruction Pointer
+WA	EQU	11	; Word Address
+TPC	EQU	12	; TIL Program Counter
+
+; Input Restrictions
+BUFFER_SIZE EQU 255
+
+CR	EQU 0DH
+LF	EQU 0AH
+DOLLAR EQU 24H
+ESC EQU 27
+
+; Screen print calls
+WRITESTR EQU 9H
+PRTCHR EQU 02H
+BDOS EQU 5H 
+
+  ORG 100h 
+
+MAIN:
+  LD DE, GREET
+  CALL PUTS
+
+READING:
+  CALL INPUT
+  JP READING
+
+INPUT:
+  LD C,11 ; C_STAT
+  LD DE,0
+  CALL BDOS
+  OR A
+  JR Z,INPUT
+	
+  LD C,6
+  LD DE,-1
+  CALL BDOS
+  OR A
+  JP Z,INPUT
+
+  CP 03H
+  JP Z, EXIT
+
+  CP 0DH
+  JP Z, EXIT
+
+  LD D, A
+  LD E, A
+  CALL PUTC
+  RET
+
+; Print a string
+PUTS:
+  LD C, WRITESTR
+  CALL BDOS
+  RET
+
+; Print a character
+PUTC:
+  LD C, PRTCHR
+  CALL BDOS
+  RET
+
+CL: DB ESC,"[H",ESC,"[2J$"
+BUFFER: DS BUFFER_SIZE
+GREET: DB "William Moore's FORTH TIL!", CR, LF, 0H
+PROMPT: DB ESC, ESC, "$ ", 0H
+
+EXIT:
+  JP 0h
+
+  END
\ No newline at end of file