-
ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... & correctness of the R register behaviour.
From ... /> [quote]Memory Refresh (R) Register.
The Z80 CPU contains ... bits of this 8-bit register are automatically incremented after ... fetched for each iteration (while BC is not 0), hence ... -
Z88DK NOOB cplot INK colorHi I am a complete NOOB with Z88DK, I am trying to draw colored circles. How does ink, paper and border work with Z88DK. I started trying to wo…
... for CALLEE functions)
POP BC ; C = x, and remove x ... ; Move X to the proper register
; D = X and ... -
Character Based SpritesHi, I'm working through Jonathan's excellent guide to writing games, and have mastered the animation of single UDGs. Before or move onto Pixel…
... />
[code]org 49997 ; RANDOMIZE USR 50000
xcor ... br />
ld bc,32
add hl,bc
... br />
ld bc,32
add hl,bc
... br /> djnz loop2
pop bc
djnz loop1
< ... -
ZX Dandanator! Mini - Cartridge system for SpectrumsHi All, I'd like to present a little HW I've developed during the last three months. It's aimed at providing a console-like usage experience for a…
... one for all games) for register data, and a 256byte replica ... )
Sets HL, DE and BC for first 16k of ram ... -
ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... A = Command, [E = Command Param], BC = Addr
;Output A = data ... H
DEC BC ; Compensate for CPI increment
register can be safely changed.
BC = Addr
;Output A = data ... -
Help needed with MIA software with custom (?) loaderHi, I've got into my hands recently a bunch of Polish educational software which are unknown MIA on WOS. I believe they are protected with some…
... ,4000
0x5CD6 LD BC,1800
0x5CD9 LDIR ... ,EA60
0x5CE1 LD BC,011B
0x5CE4 LDIR ... ROM)
0xEA90 LD BC,3B0E ; Timing constant 3B ... EXX ; Swap to altenate register file
0xEB59 POP ... -
Empire - port of trs80 basic programBack when I was a little kid, I had the opportunity to play around with a trs80 model 1 with level 2 basic. One of the games I often played was call…
... ): LET j=k1:
LET bc=USR pu: GO SUB s5: POKE ... $=STR$ a(i,k6): LET bc=USR pu:
LET z$=z ... $=STR$ a(i,k7): LET bc=USR pu: PRINT ,z$:
[/code ... -
ZX Spectrum CartridgesI have been thinking of "cloning" ZX Cartridges for a while (case, board and silicon skirt), to be able to make new releases or replace damaged cartr…
... pattern
CMDADDR LD A,(BC)[/code]
Follow the ... byte instruction [b]LD A,(BC)[/b], followed by a "manufactured ... ,R = 0x0003[/b]], due to BC contents
NOTE: Obviously ... above, it's clear that register data ([b]FA16..F14[/b ... -
Running out of fingers in AssemblyDear all, Still trying to learn Assembly and have put a few routines together. However, as my routines become a little more involved I find myself…
... into the block. The register pressure is then relieved ... enter : hl = uint num
; bc = int radix [2,36
;
; uses : af, bc, de, hl, ix
; hl = unsigned int
; bc = radix
; ix = char *buf ... -
Accessing +3 DOS with DivIDE enabledI'm thinking about making a tool that copies files from a FAT partition to a IDEDOS partition. Currently, I've got two problems: - Getting the ESX…
... /> ; call dos_set_drive
ld bc,$0501
ld de,$0002 ... nc,0
ld bc,$500
ld hl,16384 ... /> paginar:
di
ld bc,32765
ld (23388),a ... DivIDE enabled because of the USR 0 environment. At first I ... -
Where does the BASIC program sit 48K Spectrum memory?Hi there First post so be gentle, I've had a spectrum since the 80's and have recently started programming it for fun again. I wrote the followin…
... /> 1, 0, 27 LD BC,6912
237, 176 ... 65350 1, 0, 27 LD BC,6912
65353 237, ... 65362 1, 0, 27 LD BC,6912
65365 237, ... br /> Now if you RANDOMIZE USR 65344 it'll copy the ... -
Where does the BASIC program sit 48K Spectrum memory?Hi there First post so be gentle, I've had a spectrum since the 80's and have recently started programming it for fun again. I wrote the followin…
... /> 1, 0, 27 LD BC,6912
237, 176 ... 65350 1, 0, 27 LD BC,6912
65353 237, ... 65362 1, 0, 27 LD BC,6912
65365 237, ... br /> Now if you RANDOMIZE USR 65344 it'll copy the ... -
Where does the BASIC program sit 48K Spectrum memory?Hi there First post so be gentle, I've had a spectrum since the 80's and have recently started programming it for fun again. I wrote the followin…
... , and call it with RANDOMIZE USR.
I don ... LD DE,58368
LD BC,6912
LDIR
... =58368
1020 LET BC=6912
1030 POKE ... +1:
LET BC=BC-1: IF BC>0 THEN GOTO ... It simply repeats itself until BC counts down to 0. ... -
Where does the BASIC program sit 48K Spectrum memory?Hi there First post so be gentle, I've had a spectrum since the 80's and have recently started programming it for fun again. I wrote the followin…
... you were to do RANDOMIZE USR 65345 (one higher) it will ... /> 65350 1, 0, 8 LD BC,2048
65353 237, 176 ... /> 65362 1, 0, 8 LD BC,2048
65365 237, 176 ... -
How to turn OFF the "ULA Plus"??Hi. We've made a platform-game for 128k. While testing it on 2 machines with ULA+ we have noticed the colours are crap. Can You suggest h…
... ]
SetULAplusOFF:
ld bc,48955 ; register select.
ld a,64 ... -
RANDOMIZE USR, PRINT USR etcHello just wondering why is it called RANDOMIZE UsR what does randomising have to do with it ? When calling machine code routine from adress x you ty…
... resultant number.
RANDOMIZE USR n is just a convenient ... . I tend to use "LET bc=USR n" these days.
[code]
pop bc ;BC=$2d2b (discard)
pop bc ;BC=$3365
pop ... -
RANDOMIZE USR, PRINT USR etcHello just wondering why is it called RANDOMIZE UsR what does randomising have to do with it ? When calling machine code routine from adress x you ty…
When you use USR nn, it:
- Puts nn in BC.
- Execute ... a dec bc and a ret).
So USR will have ... the value of BC. What are you ... :
- PRINT USR nn will print BC on screen, ruining your ... -
Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
...
INC HL
DEC BC
LD A,B
register as value copied to screen ... because I need A register in another place. -
Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
... a so called [b]flag register[/b]. Flags are bits which ... instruction not only decreases B register but also sets [b]zero ... ]
Unfortunately [b]DEC BC doesn't influence zero flag ... />
So to check if BC=0 and correctly set zero ... -
The state of source level debuggingI was just wondering if we can put on a table everything we collectively know about source level debugging for ZX Spectrum to get an overview of curr…
... br /> usr-no: call 1E99 ; move USR addr. to BC
...
push bc ; push RANDOMIZE USR address to stack ... br /> usr-no: call 1E99 ; move USR addr. to BC
... -
Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
Doesn't make sense wouldn't this give me the value of BC ?
[code]
org 33000
LD HL, 23452
PUSH HL
POP BC
RET
[/code]
If I assemble then PRINT USR 33000
shouldn't it print 23452 on screen ? -
Graphics program in AssemblyHi so I think I'm getting the hang of this so I've done this program. It writes directly to the screen. I'm using ZX Spin. [code] LD HL,16384 LD B,…
... C, you might do PUSH BC before your call then POP ... BC afterwards to set it ... to mess with A, BC and HL then at the ... do PUSH AF, PUSH BC and PUSH HL. Then ... do POP HL, POP BC, POP AF to set ... own. Only 16-bit register pairs like BC, DE and HL. ... -
Interrupt routineI have been trying to create an interrupt routine for playing AY music in the background but cant seem to get anything working. I have a music rou…
... /> LD I,A ; Set I register to this
IM 2 ... ; Preserve all registers
PUSH BC
PUSH DE
PUSH ... '
PUSH AF
PUSH BC
PUSH DE
PUSH ...
POP DE
POP BC
POP AF
EXX ... -
how to fix instructions on screenI have a problem with my sequencer. I want the top half of the screen to stay fixed but allow the note values to print without pushing the instructio…
... can
[code]
PUSH BC
PUSH DE
PUSH ...
POP DE
POP BC
[/code]
To ... , to load into the A register.
As for the ... -
how to load machine codeI'm reading Jon Caldwell's how to write Spectrum games but can't enter the code! Here's an example:_ LD BC, (score) Call 6683 I tried putting…
... ,0,200
LD BC , 6912 is
1,0 ... code routine by
RANDOMIZE USR 61000 in BASIC
If ... -
How would you approach parallax?So ... there is this trick by Joffa that we all know...of waiting for the ULA to reach certain pattern on the screen using the IN command. And then s…
... pointed by HL via A register. And it does it in ... need to have an intermediate register A. You need to do ... . mask to a
push bc ; and put new one on ... -
Code optimisation! 16bit number to 5 digit stringJust for interest this one, any thoughts on how to make this as fast as possible? Little optimisations to this routine or a complete reimagining? …
... conversion using only registers. The register sequence is reversed for the ... :
xor a
ld bc,0802h
nh:
rl ... -
Code optimisation! 16bit number to 5 digit stringJust for interest this one, any thoughts on how to make this as fast as possible? Little optimisations to this routine or a complete reimagining? …
... br />
ld bc,-10000
call digit< ... br /> ld bc,-1000
call digit ...
ld bc,-100
call digit ... part, here the L register is only in 0-99 ... br />
ld bc, ('0'-1)*256+10 ; ... -
Akalabeth gamei found now that someone ported an ansi-basic game (coded in 1979?) to msx-basic - what about a zx-spectrum basic version of it? ;) https://plus.goo…
... /> with a call to a USR routine:
[code]
bc=FN a(w$): RETURN< ... [code]DEF FN a(a$)=USR 65368[/code]
The assembler ... ix
DRAWs: push bc
ld a,(ix+0 ... call $24b7 ;DRAW_LINE
pop bc
inc ix
inc ... -
Z88DK v1.99B ReleasedAt Sourceforge: https://sourceforge.net/projects/z88dk/ It's been a year since the last release so it was time for another. This is another tran…
... 0
;
; uses : af, bc, de, hl
push ... -bit value is sent via register L and a 32-bit ...
