-
128k Screen Flipping - Sample Code PleaseI know this has been covered before, but I cannot find out code to do the following: On a 128k Spectrum tell the speccy to display from address 4915…
... /> push hl
ld a,(de)
ld (hl),a
inc ... br /> pop hl
ld a,32
add a,l
... ld l,a
ld a,(de)
ld (hl),a ... -
Run Length DecodingRun length encoding/decoding is far less efficient than using a modern compression program.
... ld a, l
add a, 32
ld l, a
ld a, ... br />
ld hl, comic_adr ;adress in screen memomory ... br />
unpak_scr5 ld (hl), a
push af
call ... /> inc de
ld (hl), a
call slow_downhl
... -
Timex 80 column display driverI subsequently wrote an 80 column font driver for 512x192 mode.
... ,a
add hl,hl
add hl,hl
add hl,hl
ld de,font-100
add hl ... ,de
ex de,hl ... pixels
ld a,(hl) ; a = screen byte
and # ... -
Timex 80 column display driverI subsequently wrote an 80 column font driver for 512x192 mode.
You can still save a few cycles in all instances of ADD HL,BC where C is loaded with zero by using 8 bit additions via A.
LD BC,xx00 : ADD HL,BC = 21 cycles.
LD A,H : ADD A,xx : LD H,A = 15 cycles. -
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 …
... includes the instructions ADC, ADD, SBC, INC, DEC but ... I have been using the ADD HL,DE instruction to test. ... />
There is a strange exception to the rule ... outdated. But there is a newer version? Please mr. ... Fraser, make a "hard" work and type ... -
Shoot-em-up Development UpdateHi Folks, I am still working away at my horizontal scroller. Here is a link to let you see progress. I have re-written the scrolling routine to make…
... ADD A,A ; MULTIPLY BY 40
ADD A,A
ADD A,A
LD B,A
ADD A,A
ADD A,A ... [FONT=Courier New]NEXTROW EXX: ADD HL,BC: EXX[/FONT]
... -
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 …
... psuedo code :-)
load hl with the start of the ... with value pointed to by hl (ie. the current smallest number ... of hl > a then
load a with the contents of hl
end if
increment hl -
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,101h ; set the first value to hl
ld a,0
add a,(hl) ; a ... =content of hl
Checksum RoutinesHi there everybody, Does anyone have an 'off the shelf' assembler routine for generating checksums? Thanks Jim
...
add a, (hl) ; Add first byte of checksum to byte.
ld (hl),a ; Store ... a,0 ; Add, if we've got anything to carry.
ld (hl),a ...Key press to ASCII valueI need a bit of code that will give me an ASCII value when the key is pressed. I only really need a-z. I tried using the following code but it only s…
...
ld hl,KeyTransTables
add hl,de
ld a,$fe ; check ... e,80
add hl,de
NoSym: ld a,(hl) ; a = key code ...Key press to ASCII valueI need a bit of code that will give me an ASCII value when the key is pressed. I only really need a-z. I tried using the following code but it only s…
... code]
NoCaps: ld a,$f ; check on SYM ... SHIFT
in a,($fe)
... ld e,80
add hl,de
[/code]
NoCaps: ld a,$7f ; check on SYM ...Sprite adviceHello. So, I'm slowly getting to grips with Z80 assembly - currently equal parts frustration and enjoyment. Now looking for some advice to help shift…
... : I've started using a ld a,r command to grab ... [/quote]
Yeah, not a very good random number generator ... compact on PC, quite a gonzo-routine on Z80. ... br /> ld hl,(int_seed)
ld a,h
add a,a ;Set highest ...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 ... =number of bytes
;Outputs: hl=CRC16
push bc ;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…
... a,(aaa)
ld h,0
ld l,a
add hl,hl
add hl,hl ...
add hl,hl
ld de,39744
add hl,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…
... , speccy is a bit slow to draw a complex 3D scene ... . you can define a reference point for every ... 8bit signed numbers and add result to refence point. ... you avoid many 16bit ADD and RL instructions. for ... 85T ? Nope! 7T: ld (hl), a ..." Of course, this is an ...Self Relocating CodeOn page 47 of [url]http://www.tim-mann.org/trs80/doc/ldosq1-3.txt[/url] is an article about relocating code. The documented routine that performs the…
... DE,HL
ADD HL,BC
LOOP LD A,C
ADD A,(HL)
LD (HL),A ... ;reloc low byte
INC HL
ADD A ... ,B
ADC A,(HL)
LD (HL),A ;reloc high ...In Machine Code, what is the quickest way to sort bytes?I am playing around with some ordering of sprites, where I want to order them by vertical position. I used some Rodnay Zaks code to order some bytes…
... hl,ArrayAddress
add a,l
ld l,a
adc a,h ... ,a ;(hl)=(col4)
ld a,e
ld de,ArrayAddress
add a ...Pixel Explosion CodeJust a little snippet to cause explosive effects. It uses table lookups for the screen address, and can handle up to 32 pixel particles. A particle…
... ; l=ypos (0-192)
add a,(hl) ; a (containing xbyte) += hi byte of ... ; l=ypos (0-192)
add a,(hl) ; a (containing xbyte) += hi byte of ...Pixel Explosion CodeJust a little snippet to cause explosive effects. It uses table lookups for the screen address, and can handle up to 32 pixel particles. A particle…
... xpos table
ld a,(hl) ; a = x byte (e.g. if ... ; l=ypos (0-192)
add a,(hl) ; a (containing xbyte) += hi byte of ...Pixel Explosion CodeJust a little snippet to cause explosive effects. It uses table lookups for the screen address, and can handle up to 32 pixel particles. A particle…
... de,hl
ld a,h ; a = old x coord
add hl,bc
a,(hl)
inc hl
ld l,(hl)
ld h,a ; hl = dy
add hl ... ,bc
ld a,h ...Pixel Explosion CodeJust a little snippet to cause explosive effects. It uses table lookups for the screen address, and can handle up to 32 pixel particles. A particle…
... xpos table
ld a,(hl) ; a = x byte (e.g. if ... ; l=ypos (0-192)
add a,(hl) ; a (containing xbyte) += hi byte of ...Spectrum Screen Memory MapWhat's the advantage (mistery?) behind ULA's spectrum screen memory interpretation? 6144 bytes divided into 3 blocks, 2048 bytes long. if you want t…
... Spectrum is not designed as a games machine, but is designed ... as a utility machine where you do ... we could just use INC HL in the 32nd increment to ... (compare famous DOWNHL with simple ADD HL,BC) or using lookup tables ...+2 ramdisk - access in machine codeHow can you access the ramdisk in machine code? I've got a +2, and it seems the ramdisk has never been properly utilised. It would be a handy little…
... />
inc a
ld e,a
add a,a
add a,e
rra ... for source
; a'hl = source address, a' = out byte to port ... ; page in destination
ld (hl),a ; write byte
inc ...Oh so BRIGHT!What is the SLOWEST way to change the attribute area to BRIGHT? It has to be legit! No meaningless instructions or doing stuff for the sake of it. …
... add hl,de
ld de,23296
or a
sbc hl ... ,de
add hl,de
...Scrolling Loader CounterPlease can someone help me with writing a scrolling counter for a loading system. I like the Hewson counter so i`ve taken the font from zynaps loade…
... gfx
ld (hl), a ;put gfx into screen ... of gfx
inc hl ;increase it
... you have to add is a simple check ... then jump
ld hl, first_byte_of_gfx ;YES
...tips on optimizing assemblyI wrote a small routine to rotate right a whole screen character line complete with attributes. This is my third ever assembly routine, so I guess i…
... [code]
call gethl ; hl = screen address at column 31 ... scanline:
push hl ; save column 31 address
ld (hl),a ; write first byte ... a
ld a,l
add a,31
ld l,a
ld (hl ...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…
... /> add a,(hl)
add a,(hl)
add a,(hl)
add a,(hl)
add a,c
add a,(hl)
add a,(hl)
add a,c
add <…tips on optimizing assemblyI wrote a small routine to rotate right a whole screen character line complete with attributes. This is my third ever assembly routine, so I guess i…
... /> [code]
call gethl ; hl = screen address at column 31 ... address
ld (hl),a ; write first byte into ...
ld a,h ; change hl to attribute address
a
ld a,l
add a,31
ld l,a
ld (hl ...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…
According to the [URL=http://www.mdfs.net/Software/Z80/Exerciser/Spectrum/]Z80 Exerciser[/URL], some flags are wrong.
The failed tests are:
hl,
add hl,
add ix,
add iy,
bit n,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…
... tests are:
hl,
add hl,
add ix,
add iy,
bit ...
