... order and then executing a CALL instruction. This means ... the stack frame for a call to grab() looks ... ld hl,4
add hl,sp
ld c,(hl)
inc hl
a push ix so now ... stack into registers before executing a CALL into ROM (CALL ...

... hl,4
add hl,sp
ld a,(hl)
dec hl
ld d,(hl ... )
dec hl ...
ld e,(hl ...

... hl),a
jr z,next
ld a,255
ld (hl),a ... noempt
ld a,l
add a,16
ld ... l,a
call check ... br />
check ld a,(hl) ; fetch value near field< ... blocked field
ld (hl),a ; path+1
...

... hl),a
jr z,next
ld a,255
ld (hl),a ... noempt
ld a,l
add a,16
ld ... l,a
call check ... br />
check ld a,(hl) ; fetch value near field< ... blocked field
ld (hl),a ; path+1
...

... colour.
again: inc a ; Increment to next colour.
Add white paper colour.
ld hl, 22528 ; Start ... attributes.
nextch: ld (hl), a ; Store this colour.
... inc hl ; Next attribute.
...

...
ex de,hl
pop hl
ld a,(de)
or ... a
jr nz,$3 ... /> $5: ld de,30
add hl,de
djnz $2
push de
push hl
ld a,e
cp 128 ...

... push bc

ld a,b
or c
a single "or a" rather than two ... ,0; ex de,hl; add hl,bc; ex de,hl". Edit: And you ... d
ld a,d
or a
jr nz ...

... you do need a "srl a" or "sra a" -- I'm ... cycles when the equivalent "add a,a" only takes 4. The ... shifts, keep in mind "add hl,hl" which does it in ... . "adc hl,rp", like "sbc hl,rp", are a couple of ... which, unfortunately, makes them a lot less attractive.
...

... 2c 00 $0ats
add hl, de ; f98d 19 $0bts ... c3 f9 $0ats
ld a, (hl) ; f9ec 7e $07ts
add a, $60 ; fa00 c6 60 ... cb f9 $0ats
ld a, (hl) ; fa0f 7e $07ts
l_fa3c: ld a, (hl) ; fa3c 7e $07ts

... frame buffer was a simple raster, when writing a character, you ...
LD DE, 32
ADD HL, DE

which means ... up having to push a value on the stack ... reason. If you have a line where the next ... it, instead of doing a calculation to work out where ...

... To draw a character you'd have to add 32 when ... offset. You still need a character spanning check after ... i]feel[/i] like a massive saving over adding 32 ... loops just need an ADD HL,DE to advance lines, ... the Speccy layout, eliminating a line counter register and ...

...
ld h,a
ld a,l
add a,$20
ld ... l,a
ret nc ... here

ld a,h
add a,$08
ld h ... drawing loops just need an ADD HL,DE to advance lines, with ...

... learning process anyway). As a reference you might also ... /> [code]
; in HL is VRAM address
; ... /> OR B
LD (HL),A
INC L
... ... LD SP,HL ; HL holds address of background graphics
ADD HL,BC ; ... INC H
LD A,H
AND 7< ...

... with 8 bits at a time but the ... a time by the programmer. Eg, a 16-bit add like "ADD HL ... ,DE" takes 11 cycles whereas an 8-bits-at-a ... -time-equivalent "(AL = HA + DE) add a,e; ld l,a; ld a ... ,d; adc a,h" takes ...

... 've done a couple tests with HL set to things ... you go... it was a quick lunchtime thing.
HL (the 146), and doing a simple SBC ...
t_wait:
xor a ; 4
ld de, ... ld de, overhead2 ; 10
add hl, de ; 11

...

... 3 posters, here's a slightly more concise version ...
It includes a place-holder for the GPL ...
t_wait:
xor a ; 4
ld de, ... ld de, overhead2 ; 10
add hl, de ; 11

... ; 4
t_19: ld a, r ; 9
ret ...

... ld de, overhead2 ; 10
add hl, de ; 11

... xor a ; 4
ld de, overhead ; 10
sbc hl, de ... ld de, -overhead ; 10
add hl, de ; 11

ld ... -21 ; 10
.lp1: add hl, de ; 11
jp c ...

... down means there's a lower value of HL that will work ... /> ld de, -overhead ; 10
add hl, de ; 11
ld de ... , -21 ; 10
.lp1: add hl, de ; 11
jp c ...

... t_21: nop ; 4
t_17: add a,(hl) ; 7
ret ; 10 ... xor a ; 4
ld de, -overhead ; 10
add hl, de ... 10

.lp1: add hl, de ; 11
jp c ... /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ...

... t_21: nop ; 4
t_17: add a,(hl) ; 7
ret ; 10
add hl, de ; 11
ld e ... ; 7

.lp1: add hl, de ; 11
jp c ... /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ...

...
; the subtracts (add hl, -de), and jump to ... /> ld de, -overhead ; 10
add hl, de ; 11

... /> add hl, de ; 11
ld l, (hl) ; 7
jp (hl) ; ... t_21: nop ; 4
t_17: add a,(hl) ; 7
ret ; 10< ...

... 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) ... t_21: nop ; 4
t_17: add a,(hl) ; 7
ret ; 10 ...

... ; destroys: af, bc, hl
ld a, c
rra
dec hl
.b3: rra
ld hl, 0
add hl, hl
.b4: jr ... n*32 + 160T+
add hl, bc
ccf
...

... -29

delay xor a ; 4
or h ; 4 ... ld de,-d3 ; 10
add hl,de ; 11
jr delay ...

... 8000

delay xor a ; 4
or h ; 4 ... br /> skip2 ld (jump+1),a ; 13
jump jr ... ld de,-d3 ; 10
add hl,de ; 11
jr ...

... and no confinement to a 256b page (all things ... /> .b0

ld a, c
rra
jr ... nc, b4b
ld hl, 0
add hl, hl

; ...
ret nc
add hl, bc
ccf
... the delay (without a borrow from bit 5 ...

... This subroutine takes as input a single UDG byte and ... Namely that multiplication of a number by two is ... least significant bit a '-' appears (actually a 0 but I ... bit 0, not necessarily a binary 0 digit).
... it may even be a bit of a struggle to grasp ...

... going on is to do a zcc -a [other options] which ... will create a .opt file with the ... I can optimize the code a bit. I am doing ... message 1 pixel at a time in the buffer< ... add hl,de
pop de
push hl
rl (hl)
dec hl ...

... /> [code]
ld hl,3
add hl,sp ;; hl = address of the LSB ... /> ld a,(hl)
inc hl
ld h,(hl)
ld l,a ;; hl = value ... the scroll buffer in hl so a "ld hl,_scroll_buffer" will do. ... C code accessing a variable and do a "zcc -a" on the ...

... working - just shows you what a little bit of determination can ... hl
add hl,de
push hl
rl (hl)
dec hl
rl (hl ... so that I can improve a little on sending the routine ... me please?

Thanks a lot,

Adriaan