-
DEC BC/LD A,B/OR C/JP NZ,loopyesterday i saw nice trick:[code] dec bc ld a, b or c jp nz, loop can be replaced (bc starts >255, short jump) by: dec bc inc b djnz loop [/code] …
yesterday i saw nice trick:[code]
dec bc
ld a, b
or c
jp nz, loop
can be replaced (bc starts >255, short jump) by:
dec bc
inc b
djnz loop
[/code]
..nice -
Jetpac questionHi all, I just bought a copy of Jetpac off of Ebay and I'm having problems. To start, I'm trying to play it on an issue 2 Speccy with Interface 1, 2 …
... Next Address
LD A,H ; Exit loop if we have wrapped ... />
LD B,NUMPATTERNS ; Loop for each pattern
LD A,(ENDSCAN) ; Save ... LD A,B
XOR C
LD (FailedBits),A
RET
BitFadeRoutine
LD A,( ... -
RCS (Reverse Computer Screen)[B]RCS[/B] ("Reverse Computer Screen", or simply SCR written backwards) is a small utility I'm about to release, that reorders bytes from the ZX-Spec…
RCS (Reverse Computer Screen)[B]RCS[/B] ("Reverse Computer Screen", or simply SCR written backwards) is a small utility I'm about to release, that reorders bytes from the ZX-Spec…
RCS (Reverse Computer Screen)[B]RCS[/B] ("Reverse Computer Screen", or simply SCR written backwards) is a small utility I'm about to release, that reorders bytes from the ZX-Spec…
AND,XOR,OR,BIT,RES,SET,CPL,NEG,RLC,RRC,SLA,SRL,RL, RR,SRA for BASICAs this was drifting away from the original INKEY$ thread I thought that I'd create a new one. So here's a routine to provide all of the above mentio…
... /> ld c,a
ld b,0
ret
DoXOR ld a,b
xor c
ld c,a
ld b ...A fast DRAW routineI was investigating how to speed up the line drawing for the [URL="http://www.worldofspectrum.org/forums/showthread.php?t=20225"]BASIC compiler[/URL]…
... xor a ; nop
ld (__PLOTINVERSE), a
ld a, 0B6h ; or (hl)
bit 1, c ... a
sbc a, a
ld d, a
; BC = DY
ld c, b
ld b ... br /> __DRAW5: ; While loop
exx
...Short Z80 QuizQ1) Which program gives different result ? A) XOR A ADD A,A B) XOR A ADC A,A C) SCF ADD A,A D) SCF ADC A,A Q2) What is the equivalent of NEG …
... /> A)
XOR A
ADD A,A
B)
XOR A
ADC A,A
C ... )
SCF
ADD A,A
LD A,B
OR C
JR NZ,LOOP
RET
C)
LD B ...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…
... /> - draw our 'road' by using a loop to create two vertical stripes ... we want to loop.
Insert line 7, 'ld b,24 ;print road ...
dec bc
ld a,b
or c
jr nz, wait ... posn
xor a
ld b,24
fillscreen
ld (hl),a
inc ...Can Anyone explain sprites in Jet Pac/Atic Atac etcJet Pac was 16k, and yet the sprites were impressively fast. I notice they had a slight flicker at times, but were notmally pretty flicker free. W…
... ld hl, RotateTable
ld a,c
and 7
ld b,0
ld c,a ... ld (hl),a
inc l
ld a,d
xor (hl)
ld (hl),a ... br /> _SpriteLoop: DEFW 0 ; sprite loop size.
; ...Checksum RoutinesHi there everybody, Does anyone have an 'off the shelf' assembler routine for generating checksums? Thanks Jim
... ]
; and moddified to be a loop
;The arrow comments show ...Loading schemes18 years ago I hated loading schemes like Alcatraz and Speedlock because they were a b*tch to copy and became unreliable when the tape got older. Now…
... bc
ld a,b
or c
jp nz,loop
pop de ...
ld a,c
xor $03
ld c,a
ld h,$00
ld b,$b0
'orange' on a spectrumalways wondered why spectrums could never seem to achieve the colour orange? wasn't one of the default colours, and don't remember seeing anything th…
...
dec bc
ld a,b
or c
jr nz, attrfill0 ... /> ld d,a
; Invert bit 3, and save in 'e'
xor ... %00001000
ld e,a
;setup ... 'q' being pressed- loop back if not
ld a,(23560)
cp ...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 …
... /> Just move XOR A to the first line of the loop.[/quote]
ld hl, 0 ; start searching at address 0
search: xor a ; search ... /> jr z, found
ld a, b
or c ; flag decoy. BC==0 ...The Goldfinch updates thread([url=http://www.worldofspectrum.org/forums/showthread.php?t=25034]original announcement thread here[/url] - I figured it was worth starting a new to…
... re absolutely right! Adding a delay loop has fixed it. What ... 2s
#0005 LD A,B
#0006 OR C
#0007 JR ... br /> DI
LD BC,#692B
XOR A
OUT (#E3) ... data = 2bytes (**)
LD A,B
OR C
JR NZ,ABC ...Sprites masterclassHi All, You guys are probably tired of explaining sprites but I'd like to clarify a few things if possible. I've sorted the vertical aspect of scro…
... in the table
loop call sprite ;moves through the ... ld a,(column)
ld e,a
add hl,de
ld a,(hl)
xor c ... br /> djnz loop ;repeat 8 times
ld hl,bits ; ... /> xor a
ld (count),a
ld b,51
ld hl,bits
ld ix ...Serial protocol, help!Hi, simply trying to find best way to transfer programs from PC to real ZX Spectrum for testing purposes. Under Windows I tried using Spxfr and it w…
... 8-N-1. the main loop sends the screen (SCR) ... /> dec bc
ld a,b
or c
jr nz,populate ... to MSB of a | 4 t-states
xor b ; negate ... to MSB of a | 4 t-states
xor b ; negate ... to MSB of a | 4 t-states
xor b ; negate ...Need help transferring a file to a Spectrum .dsk fileHello, I was wondering if anyone can help me transfer a file that I have into a spectrum *.dsk file? The background to this request is that I have r…
... /> xor (hl)
ld e,a
dec bc
inc hl
ld a,b ...
or c
jr nz,loop
push de ...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…
... /> - draw our 'road' by using a loop to create two vertical stripes ... we want to loop.
Insert line 7, 'ld b,24 ;print road ...
dec bc
ld a,b
or c
jr nz, wait ... posn
xor a
ld b,24
fillscreen
ld (hl),a
inc ...Memory diagnostic toolIs there any sort of memory diagnostic tool for examining .Z80 files so I can easily identify large areas of blank memory? Scrolling through ZX Spin…
... c),a
ei
NEXT48: ld a,e
ld (BORDCR),a
LOOP: ld a ... ld a,56
ld (BORDCR),a
ret
CLS24: ld b ... br /> xor a
rst $10
xor a
Buzzer sounds tips'n'tricksSo I have an ARM Cortex M3 with a buzzer connected to its GPIO pin. And because I read this forum I know that there is no need to add a separate buzz…
... /> [CODE]
ld a,(speed)
ld b,a
ld c,a ;8 bits are usually ... /> [CODE]
soundlp
xor a ;set beeper output mask off ... reached 0, continue sound loop
pop de
Spike: 48k onlyDoes anyone know what's going on with Spike? [URL=http://s1142.photobucket.com/user/daveyboyhughes/media/spike_zps232a1745.gif.html][IMG]http://i114…
... /> loop ld a,(hl)
;
; encrypt/decrypt
;
dec ix
xor ... (ix+$00)
;
ld (hl),a
inc hl ... /> dec bc
ld a,b
or c
jr nz,loop
;
Assembly - Loops bigger than 255Hi, It looks like it's a bit difficult to make loops with more than 255 cycles on Z80 machine code, since the 16-bit decrements (DEC) do not alter a…
... /> LD C,D ; Load the higher byte into C
XOR A ; Prepare to test B ...
OR B ; If B is ... BC
LD A,B
OR C
JR NZ,loop ; If BC not ...Converting an integer arbitrary large binary number into a printable decimal formThis was asked a long ago at the comp.sys.sinclair newsgroup. At that time, I came up with a solution by extrapolating the classic algorithm of suces…
... BINsize)/3 (loop counter)
ld hl,$ffff
ld (hl),0 ... ld b,3 ;move 3 bits at a time (1 octal digit) ...
xor a ... BINsize bits)
ld a,b
or c
jp z,EndLoop ...Converting an integer arbitrary large binary number into a printable decimal formThis was asked a long ago at the comp.sys.sinclair newsgroup. At that time, I came up with a solution by extrapolating the classic algorithm of suces…
... ;BC=(BINsize)/3 (loop counter)
ld de,$ffff ;DE=decimal ... ld b,3 ;move 3 bits at a time (1 octal digit) ...
xor a ... BINsize bits)
ld a,b
or c
jp z, ...Animated attribute revealA new challenge to solve next. I would like to create an animated attribute reveal in machine code by having my 768 byte attributes held in ram whic…
... it's essential to include a delay loop in order to see ... ;align taps 7 (A) & 10 (E)
xor e
and ...
dec bc
ld a,b
or c
jr nz,LOOP10 ...Animated attribute revealA new challenge to solve next. I would like to create an animated attribute reveal in machine code by having my 768 byte attributes held in ram whic…
... that it cycles through the loop eight times (FLASH & ... ;align taps 7 (A) & 10 (E)
xor e
and ... /> ld a,b
or c
jp nz,LOOP10
ld bc,(CHANGED)
ld a,b ...
