-
Reason for strange display layout?I have always wondered if there is any technical reason behind the strange layout of the display file or why did Sinclair choose to do it this way?
... />
LD DE, 32
ADD HL, DE
which means ... INC L alone would mean HL points at the right address ... -
Reason for strange display layout?I have always wondered if there is any technical reason behind the strange layout of the display file or why did Sinclair choose to do it this way?
... character you'd have to add 32 when moving down scan ... drawing loops just need an ADD HL,DE to advance lines, with ... -
Reason for strange display layout?I have always wondered if there is any technical reason behind the strange layout of the display file or why did Sinclair choose to do it this way?
... /> ld a,l
add a,$20
ld l ...
ld a,h
add a,$08
ld h ... slower than an 11 cycle add but I've found ... fast as possible -- this add would mean extra pushes/pops ... drawing loops just need an ADD HL,DE to advance lines, with ... -
Game Programming Source Code & Startup HelpHi there, I'm planning on porting an existing commercial title to the speccy. I'm in the process of disassembling the original code and commenting i…
... /> [code]
; in HL is VRAM address
; in ... - graphics
LD A,(HL)
AND C
... OR B
LD (HL),A
INC L
HL ; HL holds address of background graphics
ADD HL,BC ; ... POP DE
LD SP,HL
PUSH DE
... -
Why the name "8-bit computer"?The Spectrum was called an 8-bit computer, but what does that mean? For modern hardware and operating systems (32 or 64-bit) it seems to be the poss…
... . Eg, a 16-bit add like "ADD HL,DE" takes 11 cycles whereas ... -time-equivalent "(AL = HA + DE) add a,e; ld l,a ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... wait
; Pre-req: HL > overhead
jp t_wait ... de, overhead ; 10
sbc hl, de ; 15
... /> ld de, overhead2 ; 10
add hl, de ; 11
ld ... t_wait ; 7
jp (hl) ; 4
... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... org $8000
; enter with HL = t-states to wait
sbc hl, de ; 15
... /> ld de, overhead2 ; 10
add hl, de ; 11
ld ... t_wait ; 7
jp (hl) ; 4
... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... ld de, overhead2 ; 10
add hl, de ; 11
... t_wait ; 7
jp (hl) ; 4
[/CODE ... ld de, -overhead ; 10
add hl, de ; 11
ld ... -21 ; 10
.lp1: add hl, de ; 11
jp c ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... 's a lower value of HL that will work, so having ... /> ld de, -overhead ; 10
add hl, de ; 11
ld de ... , -21 ; 10
.lp1: add hl, de ; 11
jp c ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... : nop ; 4
t_17: add a,(hl) ; 7
ret ; 10 ... ld de, -overhead ; 10
add hl, de ; 11
ld de ... 21 ; 10
.lp1: add hl, de ; 11
jp c ... br /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... : nop ; 4
t_17: add a,(hl) ; 7
ret ; 10 ... ld de, -overhead ; 10
add hl, de ; 11
ld e ... 21 ; 7
.lp1: add hl, de ; 11
jp c ... br /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... of
; the subtracts (add hl, -de), and jump to ... /> ld de, -overhead ; 10
add hl, de ; 11
; ... ; 7
.lp1: add hl, de ; 11
jp c ... /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... /> ld de, -overhead ; 10
add hl, de ; 11
... ; 7
.lp1: add hl, de ; 11
jp c ... /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ... nop ; 4
t_17: add a,(hl) ; 7
ret ; 10 ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... /> jr nc, $+2
dec hl
.b3: rra
jr ... nc, .b4
ld hl, 0
add hl, hl
.b4: jr c ... nc ; n*32 + 160T+
add hl, bc
ccf
jr ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... ld de,-d3 ; 10
add hl,de ; 11
jr delay ... similar solution using 16 bit ADD HL,DE loop would use 2 ... ld de,-d3 ; 10
add hl,de ; 11
jr delay ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... ,skip2 ; 12/7
cp (hl) ; 7 16/18
skip2 ... ld de,-d3 ; 10
add hl,de ; 11
jr delay ... -
Delay routineAs some people are aware, I have recently starting writing a [url=http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fusetest/]autom…
... 160)
; uses : af, bc, hl
.delay
< ... , $+2 ; never taken
dec hl
; bit3 set : ... nc, b4b
ld hl, 0
add hl, hl
; bit4 ... />
ret nc
add hl, bc
ccf
jr ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
... cont'd
With that part all settled, let's have a look at the UDG fatting up process.
[code]
static uchar doublew_left_helper(uchar bmp)
{
uchar i, res;
// have single byte 76543210 in bmp ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
... /> add hl,de
pop de
push hl
rl (hl)
dec hl ...
rl (hl)
dec hl
rl (hl)
dec hl ...
rl (hl)
dec hl ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
...
////////////////////////////////////////////////////////////////////
.start
ld hl,_sbuf
[/code]
[code]
ld hl,3
add hl,sp ;; hl = address of the LSB ... )
ld a,(hl)
inc hl
ld h,(hl)
ld ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
... hl
add hl,de
push hl
rl (hl)
dec hl
rl (hl ... )
dec hl
rl (hl)
dec hl ...
rl (hl)
dec hl ... -
How do I clear only a specific area of a screen (quickly) in machine code ?I'm looking for a machine code routine which will clear the first 20 rows of the Spectrum's display (or any number of rows or columns) . I have found…
... LD A,L
ADD A,C
LD ... /> LD A,L
ADD A,32
LD L ... br /> LD BC,2048
ADD HL,BC
nextLine ... -
Preferred way of determining Y co-ord in assembly?I know of 2 ways of calculating the y-cord of a pixel row for the speccy in assembly. One is to calculate the address by ways of shifting and masking…
... boundary
add hl,de ;by adding ... /> ld hl, scradd ;point hl to start ... hl)
inc hl
ld d, (hl)
ex de,hl ;hl ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
... hl
add hl,de
push hl
rl (hl)
dec hl
rl (hl ... )
dec hl
rl (hl)
dec hl ...
rl (hl)
dec hl ... -
Project: M.u.l.e.Wokani came up with a great idea about trying an open-development approach for spectrum games, and I thought why not try with a game I have under dev…
... hl
add hl,de
push hl
rl (hl)
dec hl
rl (hl ... )
dec hl
rl (hl)
dec hl ...
rl (hl)
dec hl ... -
Help hacking Split PersonalitiesI`ve been hacking away at Split Personalities for the purpose of putting new screens and graphics (items). The current screen is at 41187 and is 160…
... /> ld a,(hl)
inc hl
rla< ... rl b
add a,a
... /> ld a,(hl)
inc hl
rla< ... h,b
add hl,de
ld ... -
48K sound effectsAnybody knows where could I find some small M/C routines to play tiny beeper sounds I could use in the 48K version of a game? I don't want the 48K pl…
... /> jr nz,PlaySFXLoop2
pop hl
ld a,(CurrLevelPaperColour ...
push hl; hold amplitude for hl cycles
PlaySFXLoop3
pop hl
add hl,bc ;vary the cycle ... -
Easy Compare On 2 Byte Register?e.g. HL, BC, DE Has anybody got a really easy way of doing this without comparing each byte seperately? Any maths has no effect on the flags as far a…
Well "sbc hl," and "add hl," come to mind for comparisons ... -
Easy Compare On 2 Byte Register?e.g. HL, BC, DE Has anybody got a really easy way of doing this without comparing each byte seperately? Any maths has no effect on the flags as far a…
If you really need COMPARE (that is, content of the registers should remain unchanged), you can do this:
or a
sbc hl,de
add hl,de -
Easy Compare On 2 Byte Register?e.g. HL, BC, DE Has anybody got a really easy way of doing this without comparing each byte seperately? Any maths has no effect on the flags as far a…
... /> or a
sbc hl,de
add hl,de[/QUOTE]
ADD
and then when ... met/not met add again so you need 2 ADD HL,DE
push hl
sbc hl,de
pop hl
jr ... assume that the value in HL/DE run from 0 to ...
