Initial notes on non-compliant functionality.

agon_graphics.asm

@@ -58,7 +58,7 @@ MODE:			CALL    EXPRI
 			EXX
 			VDU	16H
 			VDU	L
-			CALL	CLRSCN				
+			CALL	CLRSCN			; VDU 22,L should itself do CLRSCN
 			JP	XEQ
 
 ; GET(x,y): Get the ASCII code of a character on screen
@@ -135,6 +135,12 @@ $$:			BIT.LIL	2, (IX+sysvar_vpd_pflags)
 ; COLOUR colour
 ; COLOUR mode,R,G,B
 ;
+; This looks wrong
+; COLOUR n must be identical to VDU 17,n
+; COLOUR n,m must be identical to VDU 19,n,m,0,0,0
+; COLOUR n,r,g,b must be identical to VDU 19,n,16,r,g,b
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
+;
 COLOUR:			CALL	EXPRI			; The colour / mode
 			EXX
 			LD	A, L 
@@ -193,6 +199,12 @@ COLOUR_1:		CALL	COMMA
 ; GCOL mode,colour
 ; GCOL mode,R,G,B
 ;
+; This looks wrong
+; GCOL n must be identical to VDU 18,0,n
+; GCOL n,m must be identical to VDU 18,n,m
+; GCOL n,r,g,b must be identical to VDU 19,n,16,r,g,b
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
+;
 GCOL:			CALL	EXPRI			; Parse MODE
 			EXX
 			LD	A, L 
@@ -254,6 +266,9 @@ COLOUR_LOOKUP:		DB	00h,00h,00h		; Black
 			DB	FFh,FFh,FFh		; White			
 
 ; PLOT mode,x,y
+; PLOT x,y must be identical to VDU 25,69,x;y;
+; PLOT n,x,y must be identical to VDU 25,n,x;y;
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
 ;
 PLOT:			CALL	EXPRI		; Parse mode
 			EXX					
@@ -270,13 +285,18 @@ PLOT_1:			VDU	19H		; VDU code for PLOT
 			JP	XEQ
 
 ; MOVE x,y
+; MOVE x,y must be identical to VDU 25,4,x;y
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
 ;
 MOVE:			CALL	EXPR_W2		; Parse X and Y
 			LD	C, 04H		; Plot mode 04H (Move)
 			JR	PLOT_1		; Plot
 
 ; DRAW x1,y1
 ; DRAW x1,y1,x2,y2
+; DRAW x,y must be identical to VDU 25,5,x;y;
+; DRAW x1,y1 TO x2,y2 must be identical to VDU 4,x1;y1; 25,5,x2;y2;
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
 ;
 DRAW:			CALL	EXPR_W2		; Get X1 and Y1
 			CALL	NXT		; Are there any more parameters?

agon_sound.asm

@@ -47,7 +47,14 @@ SOUND:			CALL	EXPR_W2			; DE: Channel/Control, HL: Volume
 ; Store	in VDU vars
 ; 
 			LD	C, A			; Store Volume in C
-			LD	A, L
+
+			LD	A, H			; Get channel high byte
+			CP	32
+			JP	NC, XEQ			; Standard channels are &0xxx to &1xxx
+							; This check should be done by MOS, but
+							; this code only passes ChannelLow to MOS
+
+			LD	A, L			; Get channel low byte to A
 			LD	(VDU_BUFFER+0), A	; Channel
 			XOR	A
 			LD	(VDU_BUFFER+1), A	; Waveform

exec.asm

@@ -244,7 +244,7 @@ $$:			LD      A, R				; Use the R register to seed the random number generator
 ;			
 XEQ0:			CALL    NEWLIN
 XEQ:			LD      (ERRLIN),IY     		; Error pointer
-			CALL    TRAP           			; Check keyboard
+			CALL    TRAP           			; Check for Escape
 XEQ1:			CALL    NXT
 			INC     IY
 			CP      ':'             		; Seperator

init.asm

@@ -50,7 +50,7 @@ RST_20:			DS		8
 RST_28:			DS		8
 RST_30:			DS		8	
 ;	
-; The NMI interrupt vector (not currently used by AGON)
+; The IRQ interrupt vector (not currently used by AGON)
 ;
 RST_38:			EI
 			RETI
@@ -74,3 +74,5 @@ $$:			LD	(HL), E
 			RET				
 
 
+; The NMI vector at 0066h also not currently used by AGON
+

main.asm

@@ -158,21 +158,21 @@ PURGE:			LD      (HL),A          	; Clear scratchpad
 			LD      (LISTON),A		
 			LD      HL,NOTICE
 			LD      (ERRTXT),HL
-			CALL    OSINIT			; Call the machine specific OS initialisation routines
+			CALL    OSINIT			; Call the machine-specific OS initialisation routines, NZ=filename passed
 			LD      (HIMEM),DE		; This returns HIMEM (ramtop) in DE - store in the HIMEM sysvar
 			LD      (PAGE_),HL		; And PAGE in HL (where BASIC program storage starts) - store in PAGE sysvar
-			CALL    NEWIT			; From what I can determine, NEWIT always returns with Z flag set
-			JP      NZ,CHAIN0       	; So this auto-run will never run
+			CALL    NEWIT			; NEWIT always returns with Z flag preserved
+			JP      NZ,CHAIN0       	; NZ set from OSINIT, auto-run passed filename
 			CALL    TELL			; Output the welcome message
 			DB    	"BBC BASIC (Z80) Version 3.00\n\r"
 NOTICE:			DB    	"(C) Copyright R.T.Russell 1987\n\r"
 			DB	"\n\r", 0
 ;			
-WARM:			DB 	F6H			; Opcode for OR? Maybe to CCF (the following SCF will be the operand)
+WARM:			DB 	F6H			; Opcode for OR, to do CLC by skipping SCF
 ;
 ; This is the main entry point for BASIC
 ;
-CLOOP:			SCF				; See above - not sure why this is here!
+CLOOP:			SCF				; SCF to indicate COLD entry
 			LD      SP,(HIMEM)
 			CALL    PROMPT          	; Prompt user
 			LD      HL,LISTON		; Pointer to the LISTO/OPT sysvar 
@@ -600,7 +600,7 @@ WARMNC:			JP      NC,WARM			; If exceeded the terminating line number then jump
 ;
 ; Check if "UNLISTABLE":
 ;
-			LD      A,D			; TODO: What is "UNLISTABLE?"
+			LD      A,D			; Line number = 0, don't list the line
 			OR      E
 			JP      Z,CLOOP
 ;
@@ -1021,6 +1021,7 @@ SETOP2:			INC     HL             		; Skip the 3 byte end of program marker (&00,
 ;
 ;NEWIT - NEW PROGRAM THEN CLEAR
 ;   Destroys: H,L
+;   MUST preserve Z/NZ for autorun
 ;
 ;CLEAR - CLEAR ALL DYNAMIC VARIABLES INCLUDING
 ; FUNCTION AND PROCEDURE POINTERS.

misc.asm

@@ -2,12 +2,11 @@
 ; Title:	BBC Basic for AGON - Miscellaneous helper functions
 ; Author:	Dean Belfield
 ; Created:	03/05/2022
-; Last Updated:	13/10/2022
+; Last Updated:	28/09/2022
 ;
 ; Modinfo:
 ; 26/07/2022:	Added NULLTOCR and CRTONULL
-; 28/09/2022:	Added CSTR_FNAME, BUF_DETOKEN, BUF_PBCDL
-; 13/10/2022:	Added CSTR_LINE
+; 28/09/2022:	Added CSTR_FNAME, BUF_DETOKEN, BUF_PBCDL
 
 			INCLUDE	"equs.inc"
 			INCLUDE	"macros.inc"
@@ -20,8 +19,7 @@
 			XDEF	SWITCH_A
 			XDEF	NULLTOCR
 			XDEF	CRTONULL
-			XDEF	CSTR_FNAME
-			XDEF	CSTR_LINE
+			XDEF	CSTR_FNAME
 			XDEF	BUF_DETOKEN
 			XDEF	BUF_PBCDL
 
@@ -162,23 +160,7 @@ CSTR_FNAME:		LD	A, (HL)			; Get source
 $$:			XOR	A			; Zero terminate the target string
 			LD	(DE), A
 			INC	DE			; And point to next free address
-			RET
-
-; Copy a CR terminated line to DE and zero terminate it
-; HL: Source
-; DE: Destination (ACCS)
-;
-CSTR_LINE:		LD	A, (HL)			; Get source
-			CP	CR			; Is it CR
-			JR	Z, $F
-			LD	(DE), A			; No, so store
-			INC	HL			; Increment
-			INC	DE			
-			JR	CSTR_LINE		; And loop
-$$:			XOR	A			; Zero terminate the target string
-			LD	(DE), A
-			INC	DE			; And point to next free address
-			RET
+			RET
 
 ; Detokenise a character into a buffer
 ;  A: Character to detokenise
@@ -228,7 +210,7 @@ $$:			LD	A, B			; If on first transition, skip this
 			CP	5			; TODO: Need to find out why 
 			JR	Z, BUF_PBCD4
 			ADD     HL,HL			; HL x  2 : We shift the number being tested left,
-			LD      D,H			;         : rrather than shifting DE right
+			LD      D,H			;         : rather than shifting DE right
 			LD      E,L			;         : This makes a lot of sense
 			ADD     HL,HL			; HL x  4
 			ADD     HL,HL			; HL x  8

patch.asm

@@ -121,6 +121,8 @@ GETIME:			PUSH 	IX
 			RET
 
 ; PUTCSR: move to cursor to x=DE, y=HL
+; TAB(x,y) Must be identical to VDU 31,x,y
+; See https://mdfs.net/Software/BBCBasic/Porting/VDUSpecs
 ;
 PUTCSR:			LD	A, 1Fh			; TAB
 			RST.LIS	10h
@@ -175,16 +177,21 @@ OSRDCH:			MOSCALL	mos_getkey		; Read keyboard
 ;           If carry set A = character
 ; Destroys: A,H,L,F
 ;
-OSKEY: 			MOSCALL	mos_getkey		; Read keyboard
+OSKEY:			BIT	7,H
+			JR	NZ,OSKEY1
+			LD	HL,0			; Negative INKEY not supported, return 0
+			AND	A
+			RET
+OSKEY1 			MOSCALL	mos_getkey		; Read keyboard
 			OR	A			; If we have a character
 			JR	NZ, $F			; Then process it
 			LD	A,H			; Check if HL is 0 (this is passed by INKEY() function
-			OR	L
-			RET	Z 			; If it is then ret
+			OR	L			; Also sets CLC for timeout
+			RET	Z 			; If it is then return
 			HALT				; Bit of a bodge so this is timed in ms
 			DEC	HL 			; Decrement the counter and 
 			JR	OSKEY 			; loop
-$$:			CP	1BH			; If we are not pressing ESC, 
+$$:			CP	1BH			; If we haven't pressed ESC, 
 			SCF 				; then flag we've got a character
 			RET	NZ		
 ;
@@ -209,6 +216,8 @@ ESCTEST:		MOSCALL	mos_getkey		; Read keyboard
 ;
 ; TRAP
 ; This is called whenever BASIC needs to check for ESC
+; NOTE This is called between every statement, so polling manually can slow the system quite a bit
+; Could use a ticker to only actually test every X calls.
 ;
 TRAP:			CALL	ESCTEST			; Read keyboard, test for ESC, set FLAGS
 ;
@@ -224,10 +233,11 @@ LTRAP:			LD	A,(FLAGS)		; Get FLAGS
 ;FILENAME.BBC is automatically CHAINed.
 ;   Outputs: DE = initial value of HIMEM (top of RAM)
 ;            HL = initial value of PAGE (user program)
-;            Z-flag reset indicates AUTO-RUN.
+;            NZ = filename passed for AUTO-RUN
+;            Z  = no filename passed
 ;  Destroys: A,D,E,H,L,F
 ;
-OSINIT:			XOR	A
+OSINIT:			XOR	A			; Z=no filename
 			LD	(FLAGS), A		; Clear flags and set F = Z
 			LD 	HL, USER
 			LD	DE, RAM_Top
@@ -411,13 +421,17 @@ STAR_FX:		CALL	ASC_TO_NUMBER		; C: FX #
 			LD	A, C 			; A: FX #, and fall through to OSBYTE	
 ;
 ; OSBYTE
-;  A: FX #
+;  A: OSBYTE/FX number
 ;  L: First parameter
 ;  H: Second parameter
 ;
-OSBYTE:			CP	13H			; We've only got one *FX command at the moment
-			JR	Z, OSBYTE_13		; *FX 13
-			JP	HUH			; Anything else trips an error
+OSBYTE:			CP	13H			; Check for calls explicitly
+			JR	Z, OSBYTE_13		; OSBYTE 19/*FX 19
+			CP	00H
+			JR	Z, OSBYTE_00		; OSBYTE 0
+			RET				; Anything else, just exit
+: NOTE *FX may generate an error for unsupported calls, but OSBYTE must *NOT*.
+; Constructs such as A%=25:CALL &FFF4 must *NOT* generate an error.
 
 ; OSBYTE 0x13 (FX 19): Wait for vertical blank interrupt
 ;
@@ -430,6 +444,14 @@ $$:			CP.LIL 	A, (IX + sysvar_time + 0)
 			LD	L, 0			; Returns 0
 			JP	COUNT0
 
+OSBYTE_00:		LD	L, 24			; CP/M-like system, must return %00011xxx
+			JP	COUNT0			; See https://beebwiki.mdfs.net/OSBYTE_%2600
+; Programs must be able to do:
+;  A%=0:X%=1:os%=((USR&FFF4)AND&FF00)DIV256
+;  d$=".":s$="/":IF(os%AND-24):d$="/":s$=".":IF(os%AND-32):d$="\"
+;  filename$=name$+s$+ext$
+
+
 ;OSLOAD - Load an area of memory from a file.
 ;   Inputs: HL addresses filename (CR terminated)
 ;           DE = address at which to load

ram.asm

@@ -94,6 +94,9 @@ INCREM:			DS		1               ; AUTO INCREMENT
 ; Extra Agon-implementation specific system variables
 ;
 FLAGS:			DS		1		; Flags: B7=ESC PRESSED, B6=ESC DISABLED, B4=COPY PRESSED
+; NOTE: FLAGS is normally USER-1, accessible as ?(PAGE-1).
+; NOTE: ACS string buffer is normally USER-768, accessible as $(PAGE-768)
+;
 ;TIME:			DS		4
 ;KEY_CODE:		DS		1
 ;VDU_BUFFER:		DS		8		; 8 bytes of temporary storage for the VDU buffer

sorry.asm

@@ -27,3 +27,5 @@ PUTIMS:
 			CALL    EXTERR
 			DEFB    "Sorry"
 			DEFB    0
+
+; Should really just return silently