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Z80 processor question...Suppose we fill the entire $0000-$ffff memory range with $ed. What will the processor do ? I suppose it will get locked, but will it still respond to…
... the second as an alternative opcode type. The second EDh byte ... -
Z80 processor question...Suppose we fill the entire $0000-$ffff memory range with $ed. What will the processor do ? I suppose it will get locked, but will it still respond to…
... EI opcodes until after the opcode following the final EI. -
Another Z80 processor questionOK, this time this isn't clearly covered in the FAQ, as far as I can see.... Suppose we have the CB instruction "SET b,r" (b=bit, r=register (differ…
... the unofficial versions of the opcode.
[quote]
My ... -
Another Z80 processor questionOK, this time this isn't clearly covered in the FAQ, as far as I can see.... Suppose we have the CB instruction "SET b,r" (b=bit, r=register (differ…
... feature IO(x) in the "opcode broken into machine cycles" list ... -
InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... /> Internally, the Z80 divides every opcode into M-cycles; each M ... /> * M1: 4 tstates: read the opcode (0x34).
* M2: 4 tstates ... bus value (0xff), coincidentally the opcode for RST 38, so the ... data bus means a random opcode could be executed, which makes ... -
Z80 core testing ?OK, my z80 core is almost finished (apart from RRD, RLD, and block instructions except LDI,LDIR,LDD,LDDR). I run the 48K rom and hurray, it resets co…
... one test for every Z80 opcode. You'll need to write ... -
InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... IM 0 depend on which opcode is executed; if there is ... -
InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... T states: 5 for an opcode fetch, 3 for pushing PC ... />
But there is no opcode fetch performed in an interrupt ... memory so the 5-cycle opcode fetch is out. You can ... peripheral supplies the "RST n" opcode. This is followed by the ... -
InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... 2 because placing an instruction opcode on the bus is a ... -
InterruptsA small piece intended for the FAQ. Comments, corrections, additions welcome. Notably: * How long does the 48K ULA hold /INT low? * What happens i…
... because placing an instruction opcode on the bus is ... understood to mean an opcode fetch cycle (called that ... M1 goes low when an opcode fetch cycle happens). But ... n" has 5 cycles of opcode fetch (OCF) from memory ... time the "RST n" opcode is supplied by the ... -
Game loop design?Having some thoughts on how to design the game loop and could do with some hints and tips from folks who have done it before! It's all about how to …
... 'proper' code as CALL draw_screen \ HALT \ JR halt_inst \.
The ... proper program
jump to HALT instruction
reenter IM2 vector ... -
Collision DetectionHi everyone, This is my first post on WOS. Like most people here I owned a Spectrum when a teenager. At that time I was quite heavily into programmin…
... the IM2 interrupt (using the HALT command)
Paint the offscreen ... -
need help with speed optimization. this procedure draws a sprite with mask from memory onto the screen with x-coordinate in pixels. it doesn't shift sprites in realtime, it just uses …
... for sprite drawing
HALT
CALL DRAWSPR ;Call sprite ... -
If there's ONE thing that......frustrated you about the spectrum when you were a kid (not now) what would it have been? 1) The attribute colour problem 2) The sound 3) The size…
I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... of loop that takes an opcode per loop and executes it ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... of loop that takes an opcode per loop and executes it ... one for every non-NOP opcode. Each test contains the state ... Z80 before and after the opcode; by seeing where your code ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... code that can take an opcode (whether as an integer, string ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
...
decode the opcode as per GOC's table ... space for various parameters the opcode will expect.
... Perform the opcode's operation, and increment your ... frequency - and handily enough, each opcode takes a number of T ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... frequency - and handily enough, each opcode takes a number of T ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... getOpcode = true) then counter = cycles(opcode)
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getOpcode = false
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decode opcode/byte (if no operands required ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... of how long an instruction opcode takes to execute, in relation ... to point to the next opcode, which you fetch and decode ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... Z80_pc
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Decide which opcode this is
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Get ... for each
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Do Opcode stuff
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Increment TStates ... by X (depends on opcode)
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Return
I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... byte opcodes. Obviously, if each opcode was only 1 byte long ... has received is the entire opcode or if it is just ... easy, once you know the opcode).
MadDoc,
I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... , they mean "get the next opcode and look *that* up in ...I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
Considering that you now have a ROM, you'll need to start emulating some opcodes.
For extra bonus points, can you tell me what opcode 243 is, and what it does?
D.I would like to write emulatorHi guys, I'm new to this forum but I realise that you must get loads of posts from people asking "how do I write an emulator" so I'll try and be spe…
... am trying to emulate the opcode INC BC. Now I know ...What *Should* Have Been the Last Game to Be PublishedHi All, Inspired by the the thread about the last public/official/etc. Spectrum game, in your opinion, what would have been the ultimate (no hint in…
... the Spectrum. Why call a halt, and put a full stop ...
