-
SBC or ADDIs this dangerous/bad practice thing to do..... I want to subtract 64 from a number, but to save a few bytes can I just add (65536-64) 65472 to the…
... few bytes can I just add
(65536-64) ... ,65472
ADD HL,BC
LD (test),HL
RET< ... need this....
LD (test),HL
RET
ADD and one to SBC,< ... with the correct value and add.
Sometimes ... -
Sort 2 byte words (x, y) on ypos, also question about swap (DE), (HL)Well that was a lot of debugging ;) But if you want a routine which takes an array of 16 byte words x, y and then sort them on y (ignoring x), I'm…
... e, c
add hl, de
cp (hl) ; cp largest with ... e, c
add hl, de
cp (hl) ; cp largest with ... , c
add hl, de
ex de, hl
pop hl
swap_word ... /> sla e
push hl
add hl, de
pop de
Z80 Emulator Source?Found a link to this on comp.sys.amstrad.8bit. i havent been with the discussion long but supposedly this is the source for a Z80 emulator. Forgive m…
How to get Grahics to wrap vertically around the screen?I am using the following code to draw an image to the screen. First I use HL to contain ROW and COLUM I then call the MapScreenFunction As I draw m…
... add hl,hl
ld de,scrtable
add hl,de
add a,(hl)
inc hl ...
ld h,(hl)
or (hl)
ld (hl),a
inc de ... de)
or (hl)
ld (hl),a
inc de ...Pixel setting / general speccy codingi just started doing some cross-coding with the [url="http://www.bigfatpanda.fsnet.co.uk/z80.html"]Z80 SNA assembler[/url] and an emulator, and this …
... hl, lineptrs
add hl, de
add hl, de
ld e, (hl)
inc hl ...
ld d, (hl ... /> add hl, de
ex de, hl
ld hl, pixelmsk ... add hl, bc
ld b, (hl)
ex de, hl
ld a, (hl ...Machine Code Sprites Example Code Using Char Based SystemBelow is my WIP code to do smooth screen wrapping sprites using char positions and offsets, as opposed to writing direct to a line (0-191) and shifti…
... LD D,0
ADD IX,DE
LD HL,gfx
ADD HL,DE
...
ps0:
ADD HL,DE
DJNZ ps0 ... HL now=FA0Ah
ADD A,(HL) ; Add the contents of HL ...IM2 Machine Code Sprites Example Code Using Char Based SystemFurther to my earlier post, here are sprites running using char method with IM2 driving it Note, for 48k spectrum using TASM [code] ; ***********…
... D,0
LD HL,gfx
ADD HL,DE
ps01:
ps0:
ADD HL,DE
DJNZ ps0
HL now=FA0Ah
ADD A,(HL) ; Add the contents of HL to ...Smooth Color Masked Sprites using fast page flip on 48kHere is a quick demo of using char based sprites using the Page flip method: a) Background is copied to buffer b) Sprites drawn on buffer c) Buffer …
... /> LD D,0
ADD HL,DE ; Add onto GFX
EX DE ... ,HL ; Let DE now point to ... , SO HL NOW=FA0AH
ADD A,(HL) ; ADD THE CONTENTS OF HL TO ...Smooth Masked Sprites using fast page flip on 48k Part 2Ok, After all the suggestions in Part 1, which were all excellent (Thankyou), I opted on the following: I have 2 x 6k Offscreen areas (Yes, that's …
... LD D,0
ADD HL,DE ; Add onto GFX
... LD DE,16
ADD HL,DE
LD (hl3a ... LD DE,16
ADD HL,DE
LD (hl4a ... LD DE,16
ADD HL,DE
LD (hl3b ...Smooth Screen Scrolling RoutineHi everyone, this is a follow up to the thread on smooth screen scrolling. As promised here is the code for the routine. It's pretty long and fairl…
... br /> ADD HL,HL ;MULTIPLY BY 2 (2 byte address)
ADD HL,DE ...
LD (MODHLA+1),HL ;HL HOLDS ... graphics
ADD HL,BC ;HL=START OF PRESHIFTED ... ;ROTATION DISPLACEMENT
ADD HL,BC ;HL = ADDRESS OF PRESHIFTED ...Index register subtractionHi, Just wondering if there a way to perform SBC HL,BC on the IX or IY registers. I can't find an op code for it, and my assembler doesn't recognise…
... a way to perform SBC HL,BC on the IX or ... . It seems strange however that ADD HL,BC can be prefixed to ...Help needed to speed up functionCan anyone help me to re-factor this code snippet. The "MAP" section holds information about which tiles go where on the screen (handled by another f…
... /> LD (HL),A
POP HL
INC HL
INC HL
INC ...
LD DE,32
ADD HL,DE
POP DE
Problem with rotating procedureHi folks! I wrote a proc in z80 asm, based on: x' = x * cos (z) - y * sin (z) y' = x * sin (z) + y * cos (z) I used a precalculated table of sin a…
... /> ld hl,cosx
add hl,bc
ld e,(hl)
inc hl
ld hl,sinx
add hl,bc
ld e,(hl)
inc hl
ld hl,sinx
add hl,bc
ld e,(hl)
inc hl
Screen LoaderCouple days ago i find very interesting loader routine in ex Yugoslavia magazine "Svet Kompjutera" from january 1987. Authors of article, calls this …
...
LD HL,49152
LD (HIL),HL
LD ... NC,LFEEA
LD HL,01045
LFEF3 DJNZ ... ADD HL,BC
EX DE,HL
ADD HL,BC
EX DE,HL ... /> LD HL,(HIL)
INC HL
LD (HIL),HL
... DE,23295
LD HL,49152+6911
JP ...Urgent Help needed to fix this: calling all machine code gurusI am currently trying to write tutorials on the amazing Orfeus music composer by Proxima which allows you to do multi channel music through the beepe…
... /> ld bc,#0044
add hl,bc
ld de,l8900< ...
adc a,d
add hl,bc
adc a,d ... />
l8ae1: push hl
call l8bcd
add a,#8b
l8bcd: pop hl
add a,a
add a,l
Mode 2 Tile Editor SourceA Timex Mode 2 Tile Editor incorporating a byte mirror table. The compiled version is available in the CSSCGC 2008 collection from the WoS archive. …
... bc,$0700 ; offset
add hl,bc ; point to second screen ... ld bc,$0020 ; offset
add hl,bc ;
ret ; return< ... ld bc,$17e0 ; offset
add hl,bc ;
call cp32bytes ; copy ... ,a ;
ld hl,mirror_tbl ;
add hl,de ;
ld ...RFC: 64 column font codeIn BASIC, type CLEAR 49999 then import the code at 50000. Then type RANDOMIZE USR 50000. This will create a new channel and attach stream #4 to it. A…
... flag
add hl,hl ; multiply
add hl,hl ; by
add hl,hl ; eight
ld ... de,font-$80 ; offset to FONT
add hl ... column offset
add hl,de ; add the offset
ex ...Question on Z80 R/W cycles.Snipped from the complete spectrum ROM disassembly: [CODE] Now the memory is checked. 11DA RAM-CHECK LD H,D Transfer the value…
... will become
ADD HL,DE reset when ... Use current HL as top.
DEC (HL) +01 ... 11EF RAM-DONE DEC HL HL points to the ...help sought with first foray into machine code - pixel scrolldownI have started to code my first machine code program, a simple roadrace game. I've based it around the pixel scrolldown routine in 40 Best Machine Co…
... /> savscrpos
push hl ;save road left side ... copy byte. . .
ld (hl),a ;. . .to next pixel ... through a char
add hl, de ;goto next ... br /> ld hl,$7e0 ;2016 added . . .
add hl, de ;to ... posn to be copied
ex de,hl ...Probing the variables in 128K modeHello again! Briefly, I'm writing an m/c routine to read some BASIC variables. So, before I start, I try to get an idea for the structure of how var…
... 0,(IY+2)
LD HL,(23627) ; VARS
...
RST $10
ADD HL,DE
JR NEXTVAR
HL
LD E,(HL)
INC HL
LD D,(HL)
INC HL ... NEXTCHAR
INC HL
LD A,(HL)
BIT 7 ... /> JR NZ,JUMP
ADD A,32
RST $ ...128 ROM paging alternativeWould this work (with the appropriate code in each ROM)? [code] ; 128 rom paging routine ; use rst 28h with call address stored after restart ;;rom…
...
ld hl, 0x0000 ; sp to hl
add hl, sp ;
ld e, (hl) ; ( ... sp) to de
inc hl ... /> back_to_r0
ld hl, bankm ; hl holds address of system variable ...New for 2009 - mc onelinersI found the limit of one line and one screen's worth of program really useful in (re-)learning BASIC, so I've decided to carry the format over into m…
...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...
add hl,de
ld (hl),a
inc hl
ld (hl),a ... ,c
add hl, de
ld a,(hl)
pop hl ;retrieve road ...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...So you want to make a cardgame......but you haven't got a good deck to display. Well here is a fully relocatable routine that will do the job for you. Place the code anywhere in me…
Tips on optimizing some newbie assembly routinesI'm starting to learn some assembly language. The best way to learn is to actually code something you are going to use, so I'm creating a very simple…
... /> add hl, hl ; * 2
add hl, hl ; * 4
add hl, hl ; * 8
ld de, _MB23_tileset
add hl ...Machine Code Microdrive File LoaderI've been experimenting with transferring games to run from microdrive. Typically I like to see a loading screen while things are happening, and I li…
... current error return
push hl ; and preserve
;
... /> ;
ld hl,filenam
ld (t_str1),hl ; address of filename ... /> push ix
pop hl
add hl,de
ld de,hd_00 ... +$54)
inc de
add hl,de
;
call $ ...Tutorial - learn machine code in 30mins[B][I]Message from the moderators[/I] - bigjon has requested that readers' attention be drawn to a better version of this tutorial, one which is easi…
...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...
add hl,de
ld (hl),a
inc hl
ld (hl),a ...Optimize this assembly?Aiming for Variable*192 -> HL In the first case, I came up with the obvious method - *128 +*64: [code] ld a, (variable) ;13 ld h,0 ; 7 ld l,…
... add hl, hl ;11
add hl, hl ;11
add hl, hl ;11
add hl, hl ;11
add hl, hl ;11
add hl, hl ... ;11
push hl ; ...Common pitfalls and solutionsLet's discuss some of the common problems in Speccy programming, and the methods we use to avoid them. For an example, here is a piece of code that …
... .
LD HL,#1303
PUSH HL
LD (#5C3D),SP ...
LD HL,#1BB0
PUSH HL
LD HL,(#5C4F)
LD ... DE,#000F
ADD HL,DE
LD DE,#1B5E ...
EX DE,HL
LD BC,4
