Well, fast forward 30 years later I still can't shake that feeling and urge to do exactly that again. For the past 3months or so I have started reading my huge collection of almost 5000 computer magazines from the early 80's and into the 90's. Starting of A through Z. At this point in time, I'm still at letter A :-)

Anyways, I picked out some of the type-ins that appeared very interresting for me, either based on the fact of stuff I wanted to try back in the days, or actual code snippets that can help me in whatever projects I'm doing on C64 or Amiga these days.

Enjoy a trip into the world of typing matters. Only this time, naturally everything is simply copied as OCR'd text from PDF, double-checked, notes added and code presented below.

I have referenced the issue and page number the original type-in was published in, so if you have the magazine available, read on for more details there!



This one was discovered in a Danish magazine called "Amiga Interface" Issue 3-1989 on page 37-38. In fact they had code listings for AmigaBasic and Assembly language in many of their magazines. Download link for magazine at bottom of page.

I am familiar with most languages, but assembly code was never my favourite topic, it was just too darn hard to understand. But still, back in the days I managed to cook together snippets of minimalstic code or just assemble random sources found on various utilities disks and see what happen and kind-of learn something.

30 years later, I decided to give it a go. Only to find my lack of memory regarding what assembler to use, how to use it and understand today how to get it to work. Since I love old-school vector graphics, I spend almost 2 days gathering the following research and successfull results below :-)

I started out thinking I have to rely on the available assembler software used back in 1989. During some research in those Danish magazines, I noticed they used SEKA, and most likely V1.5 by Kuma (not those other MasterSeka hacks, or even SEKA hacks that circulated back then). Further, knowing its 1989, we could assume its was coded (and working) on a plain stock Amiga 500 v1.3 workbench with 0.5m chip and probably 0.5m fast memory.

I loaded up my "AmigaFilesDatabase" in my searcher software (SOTDS) and found a couple of hundred filenames with "seka" in them.

My research showed that there was no difference in compiling the source code in the original SEKA v1.5 by Kuma until the latest version, including MasterSeka v1.80. ASMOne/Devpac/ASMOneTurbo all failed on something.

Oh well, here's a complete gathering of my findings and don't forget to check out the attached links and files at the bottom of this longer post.

First up, the AmigaBasic code which will generate Sin/Cos tables "RAM:TABLES" that where mentioned in the magazine to include inside the assembly source code.

REM From Amiga Interface Magazine Issue 3-1989 (page 37-38)

REM Typed/Cleaned up by Stone Oakvalley January 2018

REM /////////////////////////////////////

OPEN "ram:TABLES" FOR OUTPUT AS #1

pi=3.141592654#

s=360/512

d=0

PRINT #1,"sin_table:"

FOR a=0 TO 511

b=16384&*SIN(d*pi/180)

PRINT #1,CHR$(9)"dc.w";CHR$(9);INT(b)

d=d+s

NEXT a

d=0

PRINT #1,CHR$(13);"cos_table:"

FOR a=0 TO 511

b=16384&*COS(d*pi/180)

PRINT #1,CHR$(9)"dc.w";CHR$(9);INT(b)

d=d+s

NEXT a

CLOSE#1

STOP

Next, the assembly code to be compiled with SEKA V1.5-V3.2 (excluding v3.0) including MasterSekaV1.80 (at least). For clarity and to remember for myself, I included HOW-TO assemble and save the executable file to disk. It isn't easy when SEKA V1.5 don't have menus or I managed to find any decent user manual, heck, even the original 2 disk-set from Kuma with manual wasn't even found in my gadzillion of files gathered from Internet for the past 10 years either!

It should be noted that the code listed below the sin/cos tables are removed. However, the attached "Realtime_VectorGraphics.s" source file at the bottom is complete with sin/cos tables.

;//////////////////////////////////////

; Title: VGR (Vector Graphics Routines)

; By : Kenneth Bernholm

; For : Amiga Interface





; From Amiga Interface Magazine Issue 3-1989 (page 37-38)

; Typed/Cleaned up by Stone Oakvalley - 14/15 January 2018



; To assemble (instructions by Stone Oakvalley):

; Run SEKA V1.5 (Kuma) and set 300 as memory

; 'r' for loading file from disk (this source)

; 'a' for assemble

; 'OPTIONS>' just leave blank and press return

; 'wo' press return (for writing the executable)

; 'FILENAME>' = enter a filename, example ram:test

; and file is successfully saved as stand-alone executable?!

; The screen will boot up brown, but no spinning vector disk, mouse button

; to exit works, so does anybody know why it don't execute properly?!!



; Or if you want to run it at once directly from SEKA V1.5

; Simple type "a" for assemble, press return to ignore "OPTIONS>"

; and then "jj" (j=jump) and press enter. It will then execute from

; where the "j" label begins and show a nice floppy disk with the

; Amiga checkmark logo rotating in wireframe!

;

; A good user manual for SEKA (K-SEKA Assembler) found here:

; http://wiki.amigaspirit.hu/index.php/Amiga_Machine_Language_(Chapter_3) and section 3.3

;//////////////////////////////////////



; [[[[[[ memory reservations ]]]]]]



screen0 = $60000

screen1 = screen0+8000

progstart = screen1+8000 



org 	progstart 

load 	progstart 

	

j: 		

	jsr 		init_interrupts		;call : init _interrupts

	jsr 		init_screen		;call : init_screen

	

test_left_button:

	btst 		#6,$bfe001		;is left button pressed

	bne.s 		test_left_button	;if yes, jump

	jsr 		restore_screen		;call : restore_screen

	jsr 		restore_interrupts	;call : restore_interrupts

	clr.l 		d0			;clear exit-vector

	rts					;return to dos

	

; ###### subprogram: init_interrupts #####



init_interrupts:

	move.w 		$dff01e,sys_intreq	;store system intreq

	move.w 		$dff01c,sys_intena	;store system intena

	move.w 		#$7fff,$dff09c		;kill all requests

	move.w 		#$7fff,$dff09a		;disable all interrupts

	move.l 		$6c,sys_level3		;store system level3

	move.l 		#my_level3,$6c		;set my level3

	move.w 		#$8020,$dff09a		;enable vb-interrupt

	move.w 		#$c000,$dff09a		;master enable

	rts					;return to main



; ###### subprogram: restore_interrupts ######	



restore_interrupts:

	move.l 		sys_level3,$6c		;restore system level3

	or.w 		#$8000,sys_intena	;set enable bit

	or.w 		#$8000,sys_intreq	;set enable bit

	move.w 		sys_intreq,$dff09c	;restore system inrreq

	move.w 		sys_intena,$dff09a	;restore system intena

	rts					;return to main



; ###### subprogram: init_screen ######	



init_screen:

	move.l		4,a6			;a6=adr. of exec-library

	move.l		156(a6),a1		;a1=adr. of gfx-lib.

	move.l		38(a1),sys_copper	;store adr. of system copper

	move.l		a7,sys_stack		;store system stack

	move.l		#copper_list,$dff080	;start my copper_list

	move.w		#$0020,$dff096		;stop sprites

	rts					;return to main

	

; ##### subprogram: restore_screen ######	



restore_screen:

	move.l 		4,a6			;a6=adr. of exec-library

	move.l 		sys_copper,$dff080	;start system coppe

	move.l 		sys_stack,a7		;restore system stack

	move.w 		#$8020,$dff096		;start sprites

	rts					;return to main

	

; ###### my level3 interrupts ######	



my_level3:

	btst		#5,$dff01f		;is it a vb-interrupt

	beq.L		my_level3_exit		;if not, jump

	jsr		draw_figure		;call : draw_figure

	move.w		#0800,$dff180			

	jsr		flip_screen		;call : flip_screen

	move.w		#$0020,$dff09c		;kill all vb-requests

my_level3_exit:

	rte					;return

	

; ###### subprogram: flip_screen ######	



flip_screen:

	cmp.l		#screen1,screen_adress	;are we showing screen1

	beq.s		flip_to_screen1		;if yes, jump

	

;----  flip to screen()



	lea.l 		bpl_pointers,a0		;a0=adr. of bpl_pointers

	move.l 		#screen0,d0		;d0=adr. of screen0

	move.w 		d0,6(a0)		;set low word

	swap 		d0			;swap high/low words

	move.w 		d0,2(a0)		;set high word

	move.l 		#screen1,screen_adress	;set screen_adress

	bra.s 		flip_screen_exit	;jump	

		

;---- 	flip to screen1



flip_to_screen1:

	lea.l 		bpl_pointers,a0 	;a0=adr. of bpl_pointers

	move.l 		#screen1,d0 		;d0=adr. of screen1

	move.w 		d0,6(a0) 		;set low word

	swap 		d0 			;swap high/low words

	move.w 		d0,2(a0) 		;set high word

	move.l 		#screen0,screen_adress 	;set screen_adress

	

flip_screen_exit:

	rts					;return to main

	

; ##### subprogram : draw_figure #####	



draw_figure:

	btst 		#14,$dff002 		;is blitter busy

	bne.s 		draw_figure 		;if yes, jump

	move.l 		#$01000000,$dff040	;set control()

	move.l 		screen_adress,$dff054 	;set destination

	move.w 		#0,$dff066 		;set modulo d

	move.w 		#[200*64]+20,$dff058 	;set size (start blitter)

	move.l 		#$00008000,$dff072	;sel blitter source data

	move.l 		#$ffffffff,$dff044 	;set first mask for a

	move.w 		#40,$dff060 		;modulo c=width

	

;----	calculate new degrees	



	move.l 		xdelta,d0 		;d0=xdelta

	add.l 		d0,xgrad 		;set new xgrad

	and.l		#$000001ff,xgrad	;kill all over 511

	move.l 		ygrad,d6 		;d6=ygrad

	add.l 		ydelta,d6 		;d6=ygrad+ydelta

	and.l 		#$000001ff,d6 		;kill all over 511

	move.l 		d6,ygrad 		;store ygrad

	lsl.w 		#1,d6 			;d6=ygrad*4

	move.l 		zgrad,d7 		;d7=zgrad

	add.l 		zdelta,d7 		;d7=zgrad+zdelta

	and.l 		#$000001ff,d7		;kill all over 511

	move.l 		d7,zgrad 		;store zgrad

	lsl.w 		#1,d7 			;d7=zgrad*4

		

;---- 	rotate figure



	move.l 		screen_adress,a0 	;a0=adr. of screen

	lea.l 		figure1,a1		;a1=adr. of figure1

	lea.l 		sin_table,a2 		;a2=adr. of sin_table

	lea.l 		cos_table,a3 		;a3=adr. of cos_lable

	lea.l 		octant_table,a4 	;a4=adr. of octant_table

draw_figure2:

	cmp.w 		#555,(a1)		;is this the end

	beq.L 		draw_figure_exit 	;if yes, jump

	move.l 		xgrad,d5 		;d5=xgrad

	lsl.w 		#1,d5 			;d5=xgrad*4		

		

;----	rotate around x-axis



	move.w 		(a3,d5),d0 		;d0=cos(xgrad)

	muls 		4(a1),d0 		;d0=y*cos(xgrad)

	move.w	 	(a2,d5),d1		;d1=sin(xgrad)

	muls 		6(a1),d1 		;d1=z*sin(xgrad)

	sub.l 		d1,d0 			;d0=y*cos(xgrad)-z*sin(xgrad)

	lsl.l 		#2,d0 			;multiply d0 with 4

	move.l 		d0,y1 			;set yl

	move.w 		(a2,d5),d0 		;d0=sin(xgrad)

	muls 		4(a1),d0		;d0=y*sin(xgrad)

	move.w 		(a3,d5),d1 		;d1=cos(xgrad)

	muls 		6(a1),d1 		;d1=z*cos(xgrad)

	add.l 		d1,d0 			;d0=y*sin(xgrad)+z*cos(xgrad)

	lsl.l 		#2,d0 			;multiply d0 with 4

	move.l		d0,z1 			;set zl		

		

;----	rotate around y-axis



	move.w 		(a3,d6),d0 		;d0=cos(ygrad)

	muls 		2(a1),d0	 	;d0=x*cos(ygrad)

	move.w 		(a2,d6),d1	 	;d1=sin(ygrad)

	muls 		z1,d1 			;d1=z*sin(ygrad)

	sub.l 		d1,d0 			;d0=x*cos(ygrad)-z1*sin(ygrad)

	lsl.l 		#2,d0 			;multiply d0 with 4

	move.l 		d0,x2			;set x2

	move.w 		(a2,d6),d0		;d0=sin(ygrad)

	muls 		2(a1),d0 		;d0=x*sin(ygrad)

	move.w 		(a3,d6),d1 		;d1=cos(ygrad)

	muls 		z1,d1 			;d1=z1*cos(ygrad)

	add.l	 	d1,d0 			;d0=x*sin(ygrad)+z1*cos(ygrad)

	lsl.l 		#2,d0 			;multiply d0 with 4

	swap 		d0 			;divide d0 with 65535

	ext.l 		d0 			;extend to longword

	move.l 		d0,z2 			;set z2		

		

;----	rotate around z-axis



	move.w 		(a3,d7),d0 		;d0=cos(zgrad)

	muls 		x2,d0			;d0=x2*cos(zgrad)

	move.w 		(a2,d7),d1 		;d1=sin(zgrad)

	muls 		y1,d1 			;dl=y1*sin(zgrad)

	sub.l	 	d1,d0 			;d3=x2*cos(zgrad)-y2*sin(zgrad)

	lsl.l	 	#2,d0 			;multiply d0 with 4

	swap 		d0 			;divide d0 with 65535

	ext.l	 	d0 			;extend to longword

	move.w 		(a2,d7),d1 		;d1=sin(zgrad)

	muls 		x2,d1			;d1=x2*sin(zgrad)

	move.w 		(a3,d7),d2		;d2=cos(zgrad)

	muls 		y1,d2			;d2=y1*cos(zgrad)

	add.l 		d2,d1			;d1=x2*sin(zgrad)+y2*cos(zgrad)

	lsl.l	 	#2,d1			;multiply d1 with 4

	swap 		d1 			;divide d1 wilh 65535

	ext.l 		d1 			;extend to longword		

		

;----	translate from 3d to 2d



	move.l 		yviewpoint,d2 		;d2=yviewpoint

	muls 		d0,d2 			;d2=yviewpoint*x3

	move.l 		viewdistance,d4		;d4=viewdistance

	add.l 		d1,d4 			;d4=viewdistance+y3

	divs 		d4,d2 			;d2=d2/d4

	ext.l 		d2 			;extend to longword

	add.l 		xorigo,d2 		;add xorigo to x-position

	move.l 		last_x_point,d0 	;d0=x1

	move.l 		d2,last_x_point		;store x-position

	move.l 		d1,d3			;d3=y3

	add.l 		yorigo,d3 		;d3=y3+yorigo

	move.l 		zviewpoint,d4 		;d4=zviewpoint

	sub.l 		z2,d4 			;d4=zviewpoint-z2

	muls 		d3,d4			;d4=d4*d3

	add.l 		viewdistance,d1		;d1=viewdistance+y3

	divs 		d1,d4 			;d4=d4/d1

	ext.l 		d4 			;extend to longword

	add.l 		z2,d4 			;add z2 to d4

	lsr.l 		#1,d4 			;d4=y4/2

	move.l 		zorigo,d3 		;d3=zorigo

	sub.l 		d4,d3 			;d3=zorigo-y4/2 = y2

	move.l 		last_y_point,d1		;d1=yl

	move.l 		d3,last_y_point		;store y-position		

		

;----	draw line



	tst.w		(a1) 			;move?

	beq.L 		draw_figure3 		;if yes, jump

	cmp.l 		d0,d2 			;compare x-coords

	bne.l 		draw1 			;if not equal, jump

	cmp.l 		d1,d3 			;compare y-coords

	bne.L 		draw1 			;if not equal, jump

	bra.l 		draw_figure3 		;jump		

		

;----	d4=start-adress for line



draw1: 

	move.l		d1,d4 			;d4=yl

	move.l 		d4,d5 			;d5=yl

	lsl.w 		#5,d4 			;d4=yl*32

	lsl.w 		#3,d5 			;d5=yl*8

	add.l 		d5,d4 			;d4=y1*40

	move.l 		d0,d5 			;d5=xl

	lsr.w 		#3,d5 			;d5=xl/8

	add.l 		d5,d4 			;add d5 to d4

	add.l 		a0,d4 			;add bitplane-adress to d4

		

;----	calculate octant & delta



	move.l		#0,d5 			;clear d5

	sub.w 		d1,d3 			;d3=deltay (y2-y1)

	roxl.b		#1,d5			;scroll neg-sign in deltay

	tst.w 		d3	 		;restore n-flag ?

	bge.s		y2gy1 			;jump if deltay is positive

	neg.w 		d3 			;else invert deltay



y2gy1: 	sub.w 		d0,d2 			;d2=deltax (x2-x1)

	roxl.b 		#1,d5 			;scroll neg-sign in deltax

	tst.w 		d2 			;restore n-flag		

	bge.s 		x2gx1			;jump if deltax is positive

	neg.w 		d2			;else invert deltax

		

x2gx1: 		

	move.w 		d3,d1			;d1=deltay

	sub.w 		d2,d1			;dl=deltay-deltax

	bge.s 		dygdx			;jump if deltay>deltax

	exg 		d2,d3			;d2=smallest data

		

dygdx: 	roxl.b 		#1,d5			;d5=number of actual octant

	move.b 		(a4,d5),d5		;d5=octant-code

	lsl.l		#1,d2			;d2=smallest data*2

	and.w 		#$000f,d0		;first 4 bits of x1

	ror.w 		#4,d0			;set shift-value

	or.w		#$0bfa,d0		;set use/miniterms

	move.l 		d3,d1			;d1=d3

	lsl.w 		#6,d3			;d3=length*64

	addq.w 		#2,d3			;d3=length*64+2

		

draw99: btst 		#14,$dff002		;test blitter-busy bit

	bne.s 		draw99			;if not set, loop

	move.w 		d2,$dff062		;set modulo b

	sub.w 		d1,d2			;d2=d2-greatest data

	bge.s 		signn1			;jump if 2*kdelta>gdelta

	or.b 		#$40,d5			;set signed-flag

		

signn1: move.w 		d2,$dff052		;set pointer a (low word)

	sub.w		d1,d2			;d2=d2-d3

	move.w 		d2,$dff064		;set modulo a

		

;----	initialize other blitter-registers	



	move.w 		d0,$dff040 		;set shift and minterms

	move.w 		d5,$dff042 		;set octant no.

	move.l 		d4,$dff048 		;set start-adress af line

	move.l 		d4,$dff054 		;set start-adress of line

	move.w 		#40,$dff066 		;modulo d=width

	move.w 		d3,$dff058		;start blitter

		

draw_figure3:

	addq.l		#8,a1			;move to next 3d-data

	bra.L 		draw_figure2		;jump

		

draw_figure_exit:

	rts					;return to main



		

;----	interrupt reservations ----

even

sys_intreq:		dc.w	0		;systems intreq

sys_intena:		dc.w	0		;systems intena

sys_level3:		dc.l	0		;systems level3 interrupt



;----	system reservations ----

even

sys_copper:		dc.l	0		;adr. of system copper

sys_stack:		dc.l 	0		;adr.of system stack



;----	screen reservations ----

even

screen_adress:		dc.l	screen0





;---- vector reservations -----

even

octant_table:

	dc.b	%00000001			;y1


	dc.b	%00010001			;y1dy = octant7



	dc.b	%00001001			;y1x2, dx


	dc.b	%00010101			;y1x2, dx>dy = octant4

	

	dc.b	%00000101			;y1>y2, x1


	dc.b	%00011001			;y1>y2, x1dy = octant0



	dc.b	%00001101			;y1>y2, xl>x2, dx


	dc.b	%00011101			;y1>y2, x1>x2, dx>dy = octant3





xorigo:			dc.l		160

yorigo:			dc.l		-100

zorigo:			dc.l		100

yviewpoint:		dc.l		250

zviewpoint:		dc.l		0

viewdistance:		dc.l		300

xgrad:			dc.l		0

ygrad:			dc.l		0

zgrad:			dc.l		0

xdelta:			dc.l		5

ydelta:			dc.l		3

zdelta:			dc.l		1

y1:			dc.l		0

z1:			dc.l		0

x2:			dc.l		0

z2:			dc.l		0

last_x_point:		dc.l		0

last_y_point:		dc.l		0



;		command(0=move,1=draw),x,z,y



figure1:

dc.w 	0,-65,0,65,1,65,0,65,1,65,0,-80,1,-57,0,-80,1,-65,0,-72,1,-65,0,65,0,-53,0,65

dc.w 	1,-53,0,-20,1,53,0,-20,1,53,0,65,0,55,0,55,1,61,0,55,1,61,0,49,1,55,0,49

dc.w	1,55,0,55,0,-34,0,-80,1,-34,0,-34,1,53,0,-34,1,53,0,-80,1,32,0,-80,1,32,0,-34

dc.w 	0,-24,0,-73,1,-24,0,-37,1,-8,0,-37,1,-8,0,-73,1,-24,0,-73,0,-40,0,30,1,-15,0,0

dc.w 	1,25,0,55,0,-30,0,30,1,-5,0,0,1,35,0,55,0,-20,0,30,1,5,0,0,1,45,0,55,0,-65,50,65

dc.w 	1,65,50,65,1,65,50,-80,1,-57,50,-80,1,-65,50,-72,1,-65,50,65,0,-53,50,65

dc.w	1,-53,50,-20,1,53,50,-20,1,53,50,65,0,55,50,55,1,61,50,55,1,61,50,49,1,55,50,49

dc.w 	1,55,50,55,0,-34,50,-80,1,-34,50,-34,1,53,50,-34,1,53,50,-80,1,32,50,-80

dc.w 	1,32,50,-34,555,555,555,555



;----	my copper_list ----

even

copper_list:

	dc.w 		$0100,$1200 		;bitplane control

	dc.w 		$0104,$0024 		;video priority

	dc.w 		$0102,$0000 		;bitplane scroll-value

	dc.w 		$0108,$0000 		;bitplane modulo odd

	dc.w 		$010a,$0000 		;bilplane modulo even

	dc.w 		$008e,$2c81 		;window upper-left corner

	dc.w 		$0090,$f4c1 		;window bottom-right corner

	dc.w 		$0092,$0038 		;datafeteh start

	dc.w 		$0094,$00d0 		;datafeteh stop

		

bpl_pointers:

	dc.w 		$00e0,$0007		;bitplane 1 high

	dc.w 		$00e2,$5000		;bitplane 1 low

		

	dc.w 		$0180,$0000		;ink 0

	dc.w		$0182,$00f0 		;ink 1

		

	dc.w 		$ffff,$fffe		;wait for vbi



; #####	table of sinus-values from 0 to 511 ####



; inject the "RAM:TABLES" file created with the AmigaBasic source here



thend:	

	dc.b		'the end',0

		

	end 

Finally, to top it all off, I included every SEKA version I could find, created a bootable V1.3 disk with minor CLI commands for you, both source code listed above and also some instructions of what on the disk. Kind of a cover-disk to this story! :-)

I also included which is probably the only suitable manual for SEKA (K-SEKA) and other assemblers on Amiga "http://wiki.amigaspirit.hu/index.php/Amiga_Machine_Language_(Chapter_3)".

Since I don't trust other sites to be "out there" as long as I have intended, I took the liberty of copy/paste the SEKA section and uploaded that file to my server too!

In fact, I get so frustrated that there isn't any "love" for K-SEKA. Everybody seems to hate it. For this matter, I found a Danish/English Machine Code course that uses K-SEKA as their reference. At least something!