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writing an emulator-newbie needs helpHi, this is my first post here. I decided to write a minimalistic emulator of ZX Spectrum-no emulation of advanced peripherals, no emulation of sound…
... gasman;543986]No - the flags act as if you're ... 255.
The Z80 may well be doing a ... internally and cleverly munging the flags, but if so, that ... carry and half-carry flags on a subtraction are ... were added bit by bit, starting from right end (bit 0) and ... -
binutils questionSince there's a few people using binutils these days I thought I'd give it a go and see whether it solves my hunt for a replacement assembler/librari…
... used 256 bytes for 256 flags instead of 32 bytes because ... I left each of the flags to have their own byte ... a single bit. sdcc implements this and on the z80 this translates ... into set,bit,res instructions. However ... -
Where to start?..Hello, First off, sorry if this is in the wrong and sorry if the questions I'm about to ask have been asked and answered numerous time! Little back…
... listed them all for the Z80 processor in the Speccy. ... resource I've found for Z80 programming:
[URL=" ... the [URL="http://www.z80.info/"]site[/URL], but ... take to execute, what system flags (e.g. carry, zero) ... data; typically a 16-bit number, with the low ... -
Where to start?..Hello, First off, sorry if this is in the wrong and sorry if the questions I'm about to ask have been asked and answered numerous time! Little back…
... them all for the Z80 processor in the Speccy.[/ ... resource I've found for Z80 programming:
[URL="http ... the [URL="http://www.z80.info/"]site[/URL], but ... take to execute, what system flags (e.g. carry, zero) ... data; typically a 16-bit number, with the low ... -
Testing Z80 op codesHappy new year all! I'm currently testing my Z80 emulator (hand written from scratch in C#) and I've possibly now gone insane, testing is taking hug…
... ZEXDOC) and also undocumented Z80 instructions (ZEXALL), a pointer ... URL]http://mdfs.net/Software/Z80/Exerciser/Spectrum/[/URL]
... the same effect on flags. It shouldn't ... For example for 8-bit instructions, you have 8 ... , and 2 8-bit values you start with ... -
Creating a new game - AssemblySo... finally I?m studying Assembly Z80... after 36 years. :) Well... it?s sooooooooooooo hard to make a game using Assembly? I bought a book (Spectr…
... ... finally I?m studying Assembly Z80... after 36 years. :)
Well ... % if you follow it through. Z80 assembly itself is not hard ... just need to learn which flags and registers they affect, and ... />
The somewhat more difficult bit is figuring out how to ... -
PLOT and DRAW in machine codeHow do you go about it? If I posted a really simple BASIC instruction could someone do a machine code routine so I could learn from it? I wouldnt k…
... 14 cycles). Conceptually, the z80 sticks H and L side ... code instructions supplied by the z80 can treat the number as ... is not supported by the z80 hardware).
So ... long binary bit patterns. Bit patterns show up everywhere -- in flags, graphics, ... -
Creating a new game - AssemblySo... finally I?m studying Assembly Z80... after 36 years. :) Well... it?s sooooooooooooo hard to make a game using Assembly? I bought a book (Spectr…
... hands when juggling something a bit more complicated -- sprite code is ... you have to do a bit more register use planning. It ... ) but still act on the flags. Only minor issues really, considering ... when I first started writing Z80. I still remember my first ... -
MEMPTR: Is it worth emulating?Some advice if you will :) The only info I have on MEMPTR is this document here: [url]http://zx.pk.ru/showpost.php?p=43800[/url] I notice SpecEmu h…
... =http://www.z80.info/zip/z80-documented.pdf]The Undocumented Z80 Documented[/url ... 5+3 of the flags register after a BIT n,(HL). The ... BIT 7,x setting the sign bit which is undocumented in the Z80 ... manuals. The code does something like:
BIT 7 ... -
Specbas Photo'sOK here's a place to show us some screen grabs of Specbas programs Here are some of my Invaders screen grabs [IMG]http://i699.photobucket.com/album…
... techniques be used to emulate z80 chip hardware, do you think ... be stored somewhere and then flags have to be set for ... directly.
the hardest bit of all was de-bugging ... -
RET MHello. I?ve seen in the Joffa game SAUCER a kind of loop like this LOOP LD A,R RET M JR LOOP I do know what this loop mea…
... R register to affect the flags.[/QUOTE]
flags are indeed affected by ... being routed through the Z80 ALU before being stored ... because according to the Z80 block diagram, R could ... bit register is. What I know for sure is that if flags ... -
SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
... ago, just because of BIT n,(HL), it now ... me believe that the Z80 CPU has an internal ... instruction doesn't modify the flags, this register is reset ... previous operation did set the flags, whereas it is ORed ... the state of the known flags and registers.
SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
... very internal details of the Z80, with great attention because ... information helps understanding how the Z80 is behaving internally. This ... middle of the 16-bit path, inside the Z80, is uded by ... allow me better understand how flags updates are transferred to the ...SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
... and thoroughly tests almost all Z80 instructions The good news is ... few days, after I add bit of documentation and wrap the ... good. It means that single bit is enough to keep track ... - if an instruction modifies the flags, the immediately following SCF/CCF ...Getting PC into HLHello, here's a conundrum for you... Is there a way to obtain the value of the PC register (say into HL) without using absolute addressing such as C…
... remember well, 8-bit aritmetic operations update the flags, so the ... data bus colides with the Z80 data bus, as both ... What will happen if the Z80 puts 00h (your data ... For each one, the Z80 will try to pull it ... will pass thru the Z80 MOSFET and whatever device ...Multiface 3 programming guide anywhere?I'm interested in the tantalising little bit of text at the bottom of my Multiface 3 manual (under the "Using 8K RAM" section): "Please send a SAE…
... are:
[code]
2006: Flags. Bit 1 set if in IM2 ... , bit 2 set if M3 off, bit 3 set if ... paging unlocked, bit 4 is 48k ... /> 3FD4: AY registers
3FE4: Z80 registers
[/code]Circumspect - A Spectrum Emulator for learningThis is a project that I have been playing around with for a while. It must be said, I tend to have problems getting things finished where hobbies a…
... behaviour of the Z80, and in particular undocumented flags, since I knew ... would have to be emulated. Flags optimisation (that is, not calculating ... add accurate handling of undocumented flags as an option later ... just a simple matter of bit-bashing, so I wouldn't ...Fantasy Z80 instructions?This follows on from something catmeows said in another thread, and that I've been meaning to ask for a while. This may sound daft to people with mo…
... for things like address mode flags, which register you are operating ... registers should be true 16 bit registers instead of pairs ... of 8 bit registers. This would make ... make code smaller while staying Z80 compatible, unlike new instructions.
The Pros and Cons of "alternative" assembler syntaxContinuing from [URL]http://www.worldofspectrum.org/forums/showpost.php?p=720754&postcount=72[/URL] [QUOTE=u6c87;720754]But that wouldn't change if…
... , sdas cannot assemble standard z80 source code without modification. ... probably enabled by explicit flags, but making available alternative ... Despite this being a valid z80 program, written using 8080 ... something larger than an 8-bit home computer.
Compiler conventions for passing args/return valuesI've been mulling over this for a while, but I can't spot it covered anywhere. There are various methods for passing args and return values between …
... very inefficient type on the z80 but your idea of using ... carry flag (well, all the flags) are effectively fragile, but the ... use.
2) push af: bit 0, (ix-n) to test ...Compiler conventions for passing args/return valuesI've been mulling over this for a while, but I can't spot it covered anywhere. There are various methods for passing args and return values between …
... carry flag (well, all the flags) are effectively fragile, but ... be an option. The bit instructions rarely are because they ... would look into using flags to return a bool ... most natural result on a z80. I won't disagree ... no one has a z80 backend that can make ...SE BasicAfter 13 years of development I thought I'd run out of things to optimize, but it turns out I was wrong. However, I'm now running out of time to work…
... memory map, system variables, flags, and command summary.
... SCREEN$() supports UDGs and 8-bit character sets.
[*]Scroll ... error messages.
[*]Simplified flags.
[*]Simplified key tables.
[*]Z80 LDIR block copy: PUT ...Z80: ABS(HL) functionI must be very tired but I cannot get my head around whether this function provides a correct implementation of a ABS function for a signed 16-bit va…
... and 2 bytes. The 32 bit solution saves a few more ... carry flag error indicator -- the z80 ISA is made to indicate ... regard to instructions and what flags they do or do not ...LDI questionWhen using LDI (or LDD) is it possible to access the value that is transfered from (HL) to (DE), or does the Z80 use an internal data cache to store …
... LDDR instructions affect the flags in a strange way ... flags are:
YF flag A copy of bit 1 ... /> SF, ZF, CF flags These flags are unchanged.[/QUOTE]
... uk/html/archive/dev/z80-documented.pdf"]http://rainemu ... .uk/html/archive/dev/z80-documented.pdf[/URL]
Intel x64 vs Zilog Z80Just been having a gander at the x86 CPU Architucture here: [url]http://software.intel.com/sites/default/files/m/d/4/1/d/8/Introduction_to_x64_Assemb…
... flags within this register: CF = Bit 0, PF = Bit 2, ZF = Bit 6, SF = Bit ... (emphasis mine): "The Z80 came about when Federico Faggin ... 1976 they had the Z80 on the market.[3] ... to the development of the Z80."
So ... t related to the Z80, it's the other ...LDI questionWhen using LDI (or LDD) is it possible to access the value that is transfered from (HL) to (DE), or does the Z80 use an internal data cache to store …
... same as CPI where the flags indicate if the byte ... to the S and Z flags like the CPI instruction ... http://www.myquest.nl/z80undocumented/z80-documented-v0.91.pdf"] ... s simply tied to the bit patterns of the opcodes ... a 'don't care' bit, since the result is unused ...SCF/CCF flags - new discoveryI can't believe that no one is interested in discussing the additional, previously undocumented internal state of the Z80 CPU I have discovered recen…
... to know whether the current Z80 is CMOS, because it needs ... to get hold of CMOS Z80 in this day and ... the last instruction updated the Z80 flags (in F) anyway, the ... P/V flag for NMOS Z80 emulation if this is ... the case. This is a bit kludgey, but seems the least ...ZERO Emulator - BugsI have been using Zero emulator to experiment a few routines in assembly, since it has a somewhat usable debugger. However I believe I found a few b…
...
That's the correct Z80 behaviour, DEC BC and all ... 't affect [b]any[/b] flags.
[quote]
... "condition" is a 16 bit register, like BC for example ... t a 'real' 16-bit register, its two seperate 8 ... -bit registers used to as ...
