dev: started to add OS functions

zone.asm

@@ -1,30 +1,97 @@
-; SPDX-License-Identifier: MPL-2.0
-; SPDX-FileCopyrightText: (c) 2025 A.M. Rowsell
-; ============================================================
-; ZONE OS main section
-; ============================================================
-.section "zone","acrx"
-.global zone_start
-.global os_print_vec
-.global os_getch_vec
-.global os_outbyte_vec
-.global os_inbyte_vec
-.global os_main_loop
+	;        SPDX-License-Identifier: MPL-2.0
+	;        SPDX-FileCopyrightText: (c) 2025 A.M. Rowsell
+	;        ============================================================
+	;        ZONE OS main section
+	;        ============================================================
+	.section "zone", "acrx"
+	.global  zone_start
+	.global  os_print_vec
+	.global  os_getch_vec
+	.global  os_outbyte_vec
+	.global  os_inbyte_vec
+	.global  os_main_loop
+
+	.set UARTSTATUS, 6
+	.set UARTDATA, 7
 
 zone_start:
-    ret
+	ret
 
 os_print_vec:
-    ret
+	;    this takes a character in a and sends it to the UART
+	push af
+	push bc
+	push de
+	ld   d, a
+	ld   bc, UARTSTATUS
+
+$1:
+	in  a, (c); get status byte
+	bit 0, a; test bit 0
+	jr  z, $1; jump back if UART not ready
+	ld  a, d
+	ld  bc, UARTDATA
+	out (c), a; send byte to uart
+	pop de
+	pop bc
+	pop af
+	ret
 
 os_getch_vec:
-    ret
+	ret
 
 os_outbyte_vec:
-    ret
+	;    this takes a byte in a and sends it to port in hl
+	push af
+	push bc
+	push hl
+	ld   c, l
+	out  (c), a
+	pop  hl
+	pop  bc
+	pop  af
+	ret
 
 os_inbyte_vec:
-    ret
+	;    this gets a byte from port in hl and returns it in a
+	push bc
+	push hl
+	ld   c, l
+	in   a, (c)
+	pop  hl
+	pop  bc
+	ret
 
 os_main_loop:
-    jp os_main_loop
+	jp os_main_loop
+
+zoneSignon:
+	.string "ZONE OS ver. 0.01"
+
+zoneCopyright:
+	.string "(c) A.M. Rowsell, license MPLv2"
+
+zonePrompt:
+	.string "z] "
+
+	; error messages
+
+errorSyntax:
+	.string "Syntax error!"
+
+errorTimeout:
+	.string "Command timed out."
+
+errorNotFound:
+	.string "Command/file not found."
+
+errorHardware:
+	.string "Hardware error!"
+
+errorRAMFailed:
+	.string "RAM test failed!"
+
+stringTable:
+	.word zoneSignon, zoneCopyright, zonePrompt
+	.word errorSyntax, errorTimeout, errorNotFound
+	.word errorHardware, errorRAMFailed