-
MEMPTR finally crackedThis post is mainly for emulator developers. As you may be well know there is a misterious internal register in Z80 CPU (MEMPTR) which value is set …
... it earlier). E.g.:
CPI: MSB of ALU16_01+1
in our case:
CPI: MEMPTR++
CPD: MEMPTR-- (in ... CPU is to increment or decrement 16-bit values. And task ... -
MEMPTR finally crackedThis post is mainly for emulator developers. As you may be well know there is a misterious internal register in Z80 CPU (MEMPTR) which value is set …
... it earlier). E.g.:
CPI: MSB of ALU16_01+1
in our case:
CPI: MEMPTR++
CPD: MEMPTR-- (in ... CPU is to increment or decrement 16-bit values. And task ... ; it must be read as CPI: MSB of (ALU16_01+1). There ... -
MEMPTR finally crackedThis post is mainly for emulator developers. As you may be well know there is a misterious internal register in Z80 CPU (MEMPTR) which value is set …
... . actually, INC/DEC BC are used in MEMPTR decrement cycle in our ... -
finding largest value (z80 assembly)suppose we have to write z80 program which requires to find the biggest value in a block of memory starts from the address 101h until address stored …
... -(hl)
djnz loop ; decrement b until b=0
CPI to show how clever you ... though that a version without CPI might be a touch faster ... -
Checksum RoutinesHi there everybody, Does anyone have an 'off the shelf' assembler routine for generating checksums? Thanks Jim
... next address.
dec bc ; Decrement the counter.
... byte.
ld bc,4132 ; BC store the length.
ld bc,(checksum) ; Put the result ... -
ZXSpin 0.61 Available nowHi all! Well, after a lengthy few testing cycles, I'm taking the plunge and uploading the latest version of ZXSpin, to replace the rather aged old 0…
... Spectaculator 5.3 fails in cpi, cpd and the group ( I ... ,(+1)
bit n,
cpi
And I ... -
A scrolling starfield - help needed!I have been messing on my speccy again recently and tried to do a scrolling (parallax - maybe) starfield. I know how to scroll using machine code but…
... />
STARLOOP1
PUSH BC
STARLOOP2
CALL RAND16 ... stars initially
POP BC
DEC BC
LD A, ... CALL MOVEMENT
PUSH BC ; save counter again
ADD HL,BC
DEC (HL) ; Decrement every star by 1 ... -
Machine code help pls: LDI example[deleted]
... Found code also execute if BC=0? After all this ... quote]
Nope, a CPI instruction only sets/resets the ... comparison - the value of BC doesn't enter into it ... can think of CPI as internally doing a DEC BC instruction, which ... that's the way CPI works...) -
Machine code help pls: LDI example[deleted]
... , this time regarding CPI ...
CPI compares A with ... (HL), incs HL and decs BC (the ... long:
Search CPI
JR Z, Found< ...
By heart,
CPI set Z if A=(HL ... this
CPI
JR Z,AISHL
Machine code help pls: LDI example[deleted]
... BEEP;320895]By heart,
CPI set Z if A=(HL ... ) and sets P-vlag when BC=0
You can ... do this
CPI
JR Z,AISHL
yup,
LDI/LDD
CPI/CPD
are same ... /V flag to zero when BC==0
JP PO ...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 …
...
LD BC,(FailedAddr)
LD HL,String4 ... /> LD BC,(TotalErrors)
INC BC
LD (TotalErrors),BC
... pointer
DEC C ;Decrement charcater
ADD A ... br /> Call FailedByte
POP BC
Inversion1TestPass
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 …
... concepts (jumps, flow control, routines, CPI):
[code]searchmem
[COLOR=DimGray]; ... test for bc==0 here[/COLOR]
jr ...
push hl
pop bc ; retrieve address
ret
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 …
... a = 0
ld bc, 0ffffh ; search the entire ... address 0
search: cpi ; a-(HL)
... or c ; flag decoy. BC==0
ld a, ... push hl
pop bc ; retrieve address
...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 …
... a = 0
ld bc, 0ffffh ; search the entire ... address 0
search: cpi ; a-(HL)
... or c ; flag decoy. BC==0
jr nz, ... push hl
pop bc ; retrieve address
...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 …
... />
[code]searchmem
ld bc, 0ffffh ; search the entire memory ... for 0. reset flags
cpi ; a-(HL)
jr z ...
push hl
pop bc ; retrieve address
ret
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 …
CPI and friends affect the parity ... based on the value of BC. Whilst BC > 0, the parity ... .
[code]
search: cpi ; a-(HL)
jr z ...
[COLOR=DimGray]; ... test for bc==0 here[/COLOR]
jp ...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 …
... for 0. reset flags
cpi ; a-(HL)
jr z ... found
jp pe, search ; BC!=0
ret ; not found ... br /> push hl
pop bc ; retrieve address
ret[/ ...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 …
... for 0. reset flags
cpi ; a-(HL)
jr z ... found
jp pe, search ; BC!=0
ret ; not found ... br /> push hl
pop bc ; retrieve address
ret
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 …
... for 0. reset flags
cpi ; a-(HL)
jr z ... .found
jp pe, .search ; BC!=0
ret ; not found ... br /> push hl
pop bc ; retrieve address
ret< ...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 …
... for 0. reset flags
cpi ; a-(HL)
jr z ... .found
jp pe, .search ; BC!=0
ret ; not found ... br /> push hl
pop bc ; retrieve address
ret< ...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 …
... ret po
jr .search ; BC!=0
ret ; not found ... the entire memory
.search cpi ; a-(HL)
jr ... ret po
jr .search ; BC!=0
ret ; not found ...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 …
... s worth mentioning that CPI doesn't have to ... HL = HL + 1
dec bc ;BC = BC - 1
ld ... !
cpi ;HL = HL + 1, BC = BC -1
;And ... the second routine the CPI isn't being used ...Simple text compressionI just checked one idea about text compression. Do not take it as recomendation but rather as info which can you save some time when you are solving …
...
RET Z
; Decrement string index count
DEC ... char in 'A' (also in BC for BASIC programmers). A return ...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…
...
cpi ; inc hl, dec bc, set PO=true if BC=0
CPI trick[/url] :-)Framerate of arcade gamesThe Golden Age of video games coincided with the birth of 8-bit home computing; this is why every computer of that era has a slew of really bad Pacma…
Framerate of arcade gamesThe Golden Age of video games coincided with the birth of 8-bit home computing; this is why every computer of that era has a slew of really bad Pacma…
Framerate of arcade gamesThe Golden Age of video games coincided with the birth of 8-bit home computing; this is why every computer of that era has a slew of really bad Pacma…
Spin Assembler DirectivesLeading on from [URL="http://www.worldofspectrum.org/forums/showpost.php?p=402514&postcount=65"]jp's recent post in Spin 0.7 Public Testing thread[/U…
... :
[code]
(S: '(BC)'; I: 138), (S: '(C)'; I ... : 177),
(S: 'BC'; I: 113),
(S: 'BC'#39; I: 117 ... : 11+($FFEDB9 shl 8)), (S: 'CPI'; I: 12+($FFEDA1 shl 8 ...Spin Assembler DirectivesLeading on from [URL="http://www.worldofspectrum.org/forums/showpost.php?p=402514&postcount=65"]jp's recent post in Spin 0.7 Public Testing thread[/U…
... :
[code]
(S: '(BC)'; I: 138), (S: '(C)'; I ... : 177),
(S: 'BC'; I: 113),
(S: 'BC'#39; I: 117 ... : 11+($FFEDB9 shl 8)), (S: 'CPI'; I: 12+($FFEDA1 shl 8 ...
