5 replies to this topic

[kamakazi]

Hey guys!

I was going over Andrew's lessons while also entering code in documents given to me for development purposes. The code sounded simple and interesting while actually using less lines of code to accomplish a color cycling task. However, considering that this code was written a long time ago, I need help in cross referencing to today's way.

Here's the area's I'm having trouble with upon compiling the code:

For the 2600...how do you enter equates? Here's the portion of code I entered:

COLUP0     .EQU     $06
COLUP1     .EQU     $07
CNTRLPF    .EQU     $0A
PF2        .EQU     $0F
SWCHB      .EQU     $0282

This was typed in exactly as it appears in the listing I received. When compiled using DASM...I keep getting syntax errors on these. The code references back to them like so (which is also where the errors in DASM occur):

STA $CNTRLPF
.
.
.
STA $COLUP1
.
.
.
STA $COLUP0

etc, etc. What is it that I'm doing wrong that DASM is not understanding me (or something I'm not understanding)? I can't share the whole code right now cause it's on a different PC and the new one doesn't use floppies and the old one doesn't use a million different types of memory cards. I did however learn of a new way to set a timer for the 2600.

Help me please! I want to learn Assembly and try to understand what it is I'm doing wrong. This is for the 2600. Thanks in advance!

[batari]

You should use the vcs.h header file, which has all those equates predefined (except CNTRLPF is now CTRLPF.) If you wish to use equates, use EQU (without the dot) or just =. The other errors are the $ in your STA instruction - the $ is only needed for hexadecimal numbers and not equates.

[kamakazi]

Thanks...that helped! But the code also has the following to redirect the processor:

Init:
.
.
.
Start:
.
.
.
Loop1:
.
.
.
Proc:
.
.
.
NReset:
.
.
Loop2:
.
.
.
Loop3:

DASM is now giving me unresolved errors on 5 of these: Loop1, Loop2, Loop3, NReset & Start. What else am I doing wrong?

[Thomas Jentzsch]

kamakazi, on Tue Aug 5, 2008 8:48 AM, said:

DASM is now giving me unresolved errors on 5 of these: Loop1, Loop2, Loop3, NReset & Start. What else am I doing wrong?

Post the complete source code as a file. That should make it easier to help.

[kamakazi]

Here's the code. Sorry it took so long. Finally found a blank CD!

	;	Color Demo
	;	shows almost all the colors on the left side
	;	of the screen and cycles slowly on the right

		processor 6502
		include "vcs.h"
		include "macro.h"
	
	COLUP0	EQU	$06
	COLUP1	EQU	$07
	CTRLPF	EQU	$0A
	PF2		EQU	$0F
	SWCHB	EQU	$0282

	Init:	LDA #$E0
		STA $80	               ;	initialize time counter
	Start:
		LDA $81	               ;	get contents of memory
		STA PF2                   ;	save into a pattern control register
		LDA #$03	               ;	set right side to reflection of left
		STA CTRLPF              ;               set background control register
		LDA #$55
		STA COLUP1	;	set right side color
;*******************************************************************************
***************
		LDA #$02
		STA WSYNC	;	wait for horizontal sync
		STA VBLANK	;	start vertical blanking
		STA VSYNC	;	start vertical retrace
		LDA #$2A
		STA TIM8T	                ;	set timer for vertical retrace duration
	Loop1:	LDA INTIM
		BNE Loop1	                ;	waste time
		STY WSYNC               ;	wait for horizontal sync
		STY VSYNC	;	and vertical retrace period
	Proc:	
		LDA #$24
		STA TIM64T	;	set timer for next wait
;*******************************************************************************
***************
		LDA SWCHB
		AND #$01                 ;	check for reset switch
		BNE NReset
		BRK                     	;	only interrupt avail - need vector set
	NReset:	INC $80	                ;	increment right side color cycle counter
		BNE Loop2
		LDA #$E0  	;	change color every 32/60 seconds
		STA $80    	;	reset counter
		INC $81
		LDA $81    	;	increment left side color
		STA COLUP0	;	store it in color register
;*******************************************************************************
***************
	Loop2:	LDY INTIM
		BNE Loop2 	;	waste time
		STY WSYNC	;	wait for horizontal sync
		STY VBLANK	;	end vertical blanking
		LDX #$E4  	;	number of lines to draw on screen
	Loop3:	STY WSYNC	;	wait for horizontal sync
;*******************************************************************************
****************
		STX PF1	;	change the background pattern each line
		STX COLUP1	;	change right side color with each line
;*******************************************************************************
****************
		DEX
		BNE	Loop3
		JMP	Start	;	do next screen (every 1/60th second)
	END

This is the code exactly as it appears in the documents I received, with the exception of the edits made to it as described above by batari.

[Thomas Jentzsch]

kamakazi, on Tue Aug 5, 2008 9:22 AM, said:

Here's the code. Sorry it took so long. Finally found a blank CD!

	;	Color Demo
	;	shows almost all the colors on the left side
	;	of the screen and cycles slowly on the right

		processor 6502
		include "vcs.h"
		include "macro.h"
	
	COLUP0	EQU	$06
	COLUP1	EQU	$07
	CTRLPF	EQU	$0A
	PF2		EQU	$0F
	SWCHB	EQU	$0282

	Init:	LDA #$E0
		STA $80	               ;	initialize time counter
	Start:
		LDA $81	               ;	get contents of memory
		STA PF2                   ;	save into a pattern control register
		LDA #$03	               ;	set right side to reflection of left
		STA CTRLPF              ;               set background control register
		LDA #$55
		STA COLUP1	;	set right side color
;*******************************************************************************
***************
		LDA #$02
		STA WSYNC	;	wait for horizontal sync
		STA VBLANK	;	start vertical blanking
		STA VSYNC	;	start vertical retrace
		LDA #$2A
		STA TIM8T	                ;	set timer for vertical retrace duration
	Loop1:	LDA INTIM
		BNE Loop1	                ;	waste time
		STY WSYNC               ;	wait for horizontal sync
		STY VSYNC	;	and vertical retrace period
	Proc:	
		LDA #$24
		STA TIM64T	;	set timer for next wait
;*******************************************************************************
***************
		LDA SWCHB
		AND #$01                 ;	check for reset switch
		BNE NReset
		BRK                     	;	only interrupt avail - need vector set
	NReset:	INC $80	                ;	increment right side color cycle counter
		BNE Loop2
		LDA #$E0  	;	change color every 32/60 seconds
		STA $80    	;	reset counter
		INC $81
		LDA $81    	;	increment left side color
		STA COLUP0	;	store it in color register
;*******************************************************************************
***************
	Loop2:	LDY INTIM
		BNE Loop2 	;	waste time
		STY WSYNC	;	wait for horizontal sync
		STY VBLANK	;	end vertical blanking
		LDX #$E4  	;	number of lines to draw on screen
	Loop3:	STY WSYNC	;	wait for horizontal sync
;*******************************************************************************
****************
		STX PF1	;	change the background pattern each line
		STX COLUP1	;	change right side color with each line
;*******************************************************************************
****************
		DEX
		BNE	Loop3
		JMP	Start	;	do next screen (every 1/60th second)
	END

This is the code exactly as it appears in the documents I received, with the exception of the edits made to it as described above by batari.

The initial blanks and the broken lines are your problem. Remove all all leading blanks before the labels (should be about 6 or 7) and make the comments one line again.