-
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 ... the stack
ld hl, bankm ; hl holds address of system variable ...
back_to_r0
ld hl, bankm ; hl holds address of system variable ... -
Bresenham's line algorithmHelp - I really am struggling to get my head around this algorithm. I don't know why, I coped with Cordic (SIN/COS) and integer divide routines (/10 …
... following part...
LD HL,(real328+$02) ;HL has relative Y value ... /HL to keep X>Y
LD A,H
LD ... ,L
LD L,C
LD C,A ;swap HL (Y) and ... with SGN Y
LD A,H ;HL still has relative Y ... -
Bresenhams circle algorithmI post here my final circle code to replace, if you want, the one in the ROM. It only uses integer math and runs very fast and is very compact. It is…
...
pop hl
ld A,E ;Point ...
pop hl
ld A,E ;Point ... />
EXX
LD HL,$2758 ;HL' must contain $2758 on return ... -
CHANS system variableI modified my original code to incorporate Woody's changes and avoid using the stack: [code] org 60000 save_registers: push hl push de push bc …
...
make_space:
ld hl, 30720 ; first address after attributes ...
ld de, (0x5c4f) ; current start ... BC
ld c, l ;
ex de, hl ; start of ... channel data to HL
dec hl
call 0x1655 ... -
So... you want to format your 3.5" as 720K eh?Well, i've been trying to get hold of an application to make proper use of my 3.5" +3 floppy disks but i haven't been able to find any. I stumbled up…
... is updated
LD HL,HEAD0 ; Load HL with the beginning of ... an error
LD HL,HEAD1 ; Load HL with the beginning of ... DE register will hold HL+1
LD (HL),$E5 ; The remaining ... -
Xor-shift random number generator for Z80[QUOTE=Patrik Rak;320244]Come on, people, [URL="http://www.jstatsoft.org/v08/i14/paper"]xor-shift generators[/URL] devised by Marsaglia, that's the w…
... ]
rnd ld hl,0xA280
ld de,0xC0DE
ld a,h ; t ... /> xor e
ld e,a
ld a,d ; w = w ... -
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
ld de ... ,21
add hl ... /> ld hl,23278 ;initialise car
ld a,8
ld (hl),a
ld (32900),hl ... -
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…
... LD HL,14
ADD HL,SP
LD SP,HL ; undo USR command
LD HL ... -
Understanding the StackSorry folks. I guess I'm going to be a pain for a little while. Hope it's ok with everyone. I'm currently studying the stack and wrote the little pr…
... /> ld (spp), sp
ld hl, spp
inc (hl)
inc (hl)
ld sp ... account for this when using LD SP instructions. The removal of ... -
Thinking in Assembly (first efforts)The following is one small routine to educate myself on a few concepts (jumps, flow control, routines, CPI): [code]searchmem xor a …
... the entire memory
ld hl, 0 ; start searching at ... /> search: cpi ; a-(HL)
jr z, found ... B]
found: dec hl ; get found address
push hl
pop bc ; ... -
IN 255 behaviour not emulated in Spectaculator and ZXSpinI'm not speaking about "normal" IN 255 behaviour. All of you know what I'm taking about: IN 255 can be used to "read" screen data as it's retrieved f…
... halt
ld c,255
ld hl,0
SigueTest ... in a,(c)
dec hl ... -
Fastest way to clear a screen.We haven't had an optimizing fun for some time, so let's have some: What's the fastest way to clear a screen (i.e., filling the 6912 bytes at 16384 w…
... :
[CODE]
LD HL,16384 ; 3B 10T
LD DE,16385 ; 3B ... 10T
LD BC,6911 ; 3B 10T
LD (HL),L ; 1B 7T ... -
Rainbow Generator for 48K Spectrum using PUSHThis is what I came up with from [B]gasman[/B]'s suggestions. It's stable in ZXSpin and ZX32 simulating a 48K Speccy. Anyone like to try it on the …
... ld hl,65024 ;254*256=65024
ld de,65025
ld (hl),253 ... ;Write once
ld bc, ... main interrupt routine:
ld hl,sample_jump ;Sample instruction (see ... pop de
pop hl
ld sp,22552+(32*char_row) ... -
BASin assembler/disassembler issuesI would email Dunny, but his listed homepage is nonexistant, and "send a private message to" seems to ask me to log in each time. He doesn't list an …
... /> Doing LD HL, 20+10*32
is assembled as LD HL, (30 ... -
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 ... -
FLASH EPROM programming on ZXExist any other software for rewriting FLASH EPROM or EEPROM chips on real ZX ? I know only: EEPROM flasher for original DivIDE [url]http://85.132.…
... support
org $5cd0
ld hl, $4000 ;
di ... byte as targer adress HL
ld a, $60 ; ... ; read source byte
ld (hl), a ; write byte to ... -
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…
... /> ;
main1 ld (err_sp),sp
ld hl,main2
ld (hd_11),hl ; execute main2 ... /> ;
ld hl,filenam
ld (t_str1),hl ; address of filename
;
; ld hl,1 ... us
;
ld hl,1
ld (n_str1),hl ; length of filename
Tinkering with Quique Llar?a's Midi2Ay tool...Im tinkering with Quique Llar?a's Midi2Ay tool, found at: [url]ftp://ftp.worldofspectrum.org/pub/sinclair/tools/pc/midi2ay-0.1.zip[/url] Im not a v…
... /> push AF
pop hl
ld (R_AF),hl
ld hl,(R_HL)
push AF
pop hl
ld (G_AF),hl
ld hl,(G_HL)
ld hl,(G_AF)
push hl
pop af
ld hl,(G_HL)
ld ...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…
... /> fillscreen
ld (hl),a
inc hl
ld (hl),a
ld de,9 ... /> add hl,de
ld (hl),a
inc hl
ld (hl),a
ld de ... /> ld hl,23278 ;initialise car
ld a,8
ld (hl),a
ld (32900),hl ...Z80 'EXX' ConfusionI was working on a little Z80 routine last evening, and, having run out of registers, resorted to sticking one of the values into a memory location a…
... buffer, deliberately using HL as both a memory ...
LD HL,BYTES
EXX
LD HL,32
LOOP: EXX
LD (HL),123
INC HL ...
EXX
DEC HL
LD ...Need help with interrupts againI'm fighting to understand how interrupts code handling works I'm trying to set my simple own interrupt routine, as I don't want to be dependent on …
... interrupt
DI
LD HL,23296 ;fill 256 bytes with ... 255
LD DE,23297
LD BC,255
LD (HL),C
LD HL,77*256+237
LD (65525),HL
LD A ...tricks to simplify codingWhen i started with programming in assembler i had very simple approach to do things. Just shifting bytes around, doing simple tests and so... Later …
...
[CODE]
call_from_table
;HL = table
;A = ITEM
ld a, (hl)
inc hl
ld h, (hl)
ld (call_from_table2 + 1), hl
[CODE]
ld a, (ix + FRAC_PEN)
ld hl, p2_fracpentab
call ...Some TR-DOS technical questionsHi forum, I sincerelly hope this was the right section of yours to ask this kind of stuff in. (else return facepalm;) Anyway, here's a couple of que…
... crc.
[code]l_addr ld hl,buffer ; the address to load ... [/code]
Output in (HL):
+0 - track no ...+3 assembler questionI was wondering if anyone could give any suggestions as to how to get this bit of code working on the +2A/+3 in 128k mode. It works on the +128k/+2 i…
... LIST_SP
LD A,(23622)
LD (23616),A
LD A,(23610 ... ;OSPCC - CONTINUE statement number
LD HL,(23641) ;E_LINE - address of editor ... it
EX DE,HL
LD (HL),$e8 ;insert code for "CONTINUE ...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 ...Z80 Machine Code Question...Hi Folks, I know not strictly a BASIC question but I have started to learn Z80 machine code - 25 years too late! :smile: I have been reading a book…
... ][FONT="Courier New"]LD BC,1400h
LD HL,4000h
LD(HL),FFh
Using the stack to copy memory blocksA [b]PUSH[/b] and a [b]POP[/b] instruction together take less time than two [b]LDI[/b], so long [b]POP/PUSH[/b] sequences are sometimes used to copy …
... /> ld ix, source
ld hl, dest
ld de, 8 ; stepsize
ld a ... = 54
ld sp, hl ; 6
push hl ; 11
push ...Machine code issue...Hi Folks, My trials with MCODE continue and I am stuck. I wrote the following program in BASIC to simply POKE an attribute byte in to a "box" on th…
... ;Store Y
2100FA LD HL,64000 ;HL=Address of Y
... (HL)
CB26 SLA (HL) ;64000=Y*32
2A00FA LD HL,(64000) ;HL= ... Y*32
3200FA LD (64000),A ...
