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Video generation using a CPUWe know it is possible to generate a video signal using a CPU, and this technique was often used on low-end computers in the early 1980's (for exampl…
... internal shift register during the next eight cycles.
Meanwhile ... ) and passes on to the next column of the display; since ... code 118 which is the opcode for HALT, and rather than ... interrupt is generated for the next line of the display.
ZX7: an "optimal" LZ77 packerAbout 20 years ago, I started a M.Sc. in Computing, planning to work on data compression. Although I quickly changed to another subject for a number …
... defb $cb, $33 ; opcode for undocumented instruction "SLL E ... /> rl d ; insert next bit into D
... add a, a ; check next bit
ret nz ; ...ZX7: an "optimal" LZ77 packerAbout 20 years ago, I started a M.Sc. in Computing, planning to work on data compression. Although I quickly changed to another subject for a number …
... defb $cb, $33 ; opcode for undocumented instruction "SLL E ... /> rl d ; insert next bit into D
... add a, a ; check next bit
ret nz ; ...Rocky Gush Floppy Drive InterfaceI have a Rocky Gush Floppy Drive Interface which I would like to post the details under the Hardware section of the website. What is correct procedur…
... in which the instruction's opcode is fetched), and also A14 ... (or at least the same opcode byte) in their ROM as ... has stabilised when fetching the next byte after the address which ... , $74, $00), which is the opcode for a NOP instruction.
Mirroring UDG'sJust wondered is there a quick an easy way of mirroring UDGs (byte values)? i.e. BIN 11110000 becoming 00001111 etc.
... ]
The first three opcode are clear and simple
The next part emulates a swap on ...Experimenting with turboloadersHello, My first post, having lurked here for a while. I'm a lifelong computer nerd, Spectrum fan since childhood in the eighties, and have recently…
... :
ld a,0x37 ; opcode for SCF
ld (.load_error ... call .read_edge ; read the next edge
jr z,.loader_init ... /> jr .main_loop ; fetch the next byte
. ...Spectrum CP/MHello.. Just out of curiosity, has anyone actually used +3 CP/M for any practical purpose? I remember booting it up a couple of times years ago, jus…
... :) And they did, for the next generation of cpu because really ... as per normal, triggered by opcode fetch at $66, and could ...hash function permutation tableI'm using a simple Pearson hash function to generate keys for a $(103,6) array using a 256-byte permutation table. How do I arrange the entries in th…
... = val2 = 2nd number
c = opcode = 0(OR), 1(AND), 2 ... SUB FN b(val1,val2,opcode,bits,nnnn,0)
....
oooo NEXT p: RETURN
[/code]
hash function permutation tableI'm using a simple Pearson hash function to generate keys for a $(103,6) array using a 256-byte permutation table. How do I arrange the entries in th…
... TO 64: READ t(t): NEXT t
10 ... CHR$(k+32)
95 NEXT k: PRINT dups,: STOP
NEXT i
220 GO SUB ... x$(6)*(i+1):
NEXT i
320 GO SUB ... = val2 = 2nd number
c = opcode = 0(OR), 1(AND), 2 ...Machine Code Routine of the weekHow about a thread that has a routine each week that is in [B]assembly language[/B] and is also described in great detail what the hell is going on …
... @ defb $3a - This is the opcode for LD A, (nnnn). In ... , (nnnn) and so fetches the next 2 bytes that form the ... + 2 thereby skipping to the next instruction which is INC C ...JP (HL) confusionokay.... JP nn will jump to memory address nn. JP (HL) ,I assumed would read the contents of memory address HL and jump to the location and be a gre…
... the address directly from the next two bytes in the program ... its value directly from the next byte of the program, whereas ... ' (as I write it) has opcode #e9 and 'LD SP,HL ... ' has opcode #f9 could well be more ...Features that are still wanted in Spectrum emulation.Features that are still wanted in Spectrum emulation. 4 USB joystick/gamepad input for real multiplayer games - Yes, Bomb Munchies.... - Sinclair 12…
... /> * Breakpoint on executing a certain opcode
* Breakpoint when a condition ... a boolean expression. For example: opcode==0xCF && mem[pc ... to display the error "1 NEXT without FOR"
- Feature to ...Features that are still wanted in Spectrum emulation.Features that are still wanted in Spectrum emulation. 4 USB joystick/gamepad input for real multiplayer games - Yes, Bomb Munchies.... - Sinclair 12…
... /> * Breakpoint on executing a certain opcode
* Breakpoint when a condition ... a boolean expression. For example: opcode==0xCF && mem[pc ... to display the error "1 NEXT without FOR"
- Feature ... ZEsarUX will include this in next versions ;)HALT: Why always 4ts?Instruction breakdown of halt is like that: PC 4ts. That means it fetches instruction byte from ram which tooks 4 ts and then does nothing and read…
... external hardware that changes the opcode read @ some point (I mean ... repeatedly, is that the "HALT" opcode's location (PC unchanged from ... when the HALT opcode was first fetched), or the next one (instruction ...HALT: Why always 4ts?Instruction breakdown of halt is like that: PC 4ts. That means it fetches instruction byte from ram which tooks 4 ts and then does nothing and read…
... repeatedly, is that the "HALT" opcode's location (PC unchanged from ... when the HALT opcode was first fetched), or the next one (instruction ...Help! I'm learning Machine Code...Having decided to take the plunge and learn to machine code a while ago, I have started in earnest using the much recommended 'Mastering Machine Code…
... is a so-called pseudo-opcode (an instruction for the assembler ... #9c40
[/code]
Next line, "LD (5CB0), SP" - very ...Must be missing the point - machine code... Hi Folks, Trying my hand at machine code again but falling at the first hurdle. I hand crafted the following to run at address 62000 and the co…
... />
[code]ADDR LABEL OPCODE COMMENT HEX
-------------------------------------------------------------------------------------------
... /> 62017 INC L ; Next screen byte $2C
62018 DEC C ; Next iteration of Loop2 $0D ...Must be missing the point - machine code... Hi Folks, Trying my hand at machine code again but falling at the first hurdle. I hand crafted the following to run at address 62000 and the co…
... />
[code]ADDR LABEL OPCODE COMMENT HEX
-------------------------------------------------------------------------------------------
... /> 62017 INC L ; Next screen byte $2C
62030 DEC C ; Next iteration of Loop1 $0D ...Startup colours of the Spectrum ROMHi Folks, Thought I would have a go at changing the startup colours of the Spectrum ROMs used within BasinC which ships with 48.rom (16384 bytes) …
... />
// $ED Unused Opcode Trap for Keyboard (INKEY$)
// $ED Unused Opcode Trap for BREAK detection
// $ED Unused Opcode Trap for the Error Reconstruction ... PutWord(@Memory[$1DC4], $00ED); // NEXT
// A ...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…
... length--) {
if ((*msk) == 0x01) { /* Opcode */
if (*b1-*b2) return ... tables. Table values are:
{ opcode, opcode mask, mnemonic, size, t-states ... for this instruction.
Next objective is parsing CDB files ...SkoolKit 6.0SkoolKit 6.0 has been released. SkoolKit is a set of command line utilities for disassembling Spectrum software, into assembler-friendly ASM forma…
... NOFLOW directive every time an opcode that isn't a jump ... are Zeus reserved words : FOR, NEXT, SIN, EXP, INT etc, and ...Hacking the ZX Spectrum 48K ROMHi Guys, I have modded my Speccy with a dual boot ROM loading on first bank the original ZX kernel and on the second bank an enhanced version. I h…
... address 0x11cc, which is the opcode for the Z80 instruction LD ... by the Z80 from the next address up. In this case ... , the value at the next address (0x11cd) is 07. After ...How can I make a UDG rotate?I designed a set of UDG's that can be used for making shapes or letters. Trouble is that my circle - for example - consists of 4 pieces and it would…
... zero jump to do the next row
LD B, ... ; and move HL to the next screen byte
LD A ... $CB,$32 ; SLS D (undoc.opcode)
DEFB $CB,$33 ; SLS ...INC not working as expected in LoopHi, i have been working on this for around 2 weeks now and Ive read myself into a hole. I am trying to increment HL. HL is referencing a display …
... keeps incrementing HL with the next address. When it goes past ... series of instructions with the opcode 54 (which is LD (HL ...Kempston Mouse DriverHi Folks, Does anyone know the email of Chris Cowley who wrote the Kempston Mouse Driver in the WOS Archive? Many thanks Paddy
... zero jump to do the next row
LD B, ... ; and move HL to the next screen byte
LD A ... $CB,$32 ; SLS D (undoc.opcode)
DEFB $CB,$33 ; SLS ... IX to point at the next byte of graphic data
next row down the screen
predetermined number of loops in assemblerhi, i have this code that i have already written org 40000 ld c,33 ld (23612),a ld a,c rst 16 inc c jp 40001 but i only want to loop i…
... opcode 33, which is LD HL,**. This will then interpret then next ...
