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Z80, and 6502, in comparisonI was wondering about how each of these compared in terms of performance. The Commodore 64 had a 6502 @ 1MHz, and graphics processor VIC which took …
... case if the 6502 and Z80 performed much the same per ... the 6502 performed a bit better than the Z80.
How are LAST-K and FLAGS set on a Real Spectrum?Hi, I'm writing a Spectrum emulator and I've got Horace and the Spiders working (with the wrong colours and no sound) but when I boot into ROM non…
... ) but the ROM uses bit 5 of FLAGS and LAST-K to ... far as I can tell, FLAGS and LAST-K aren't ... , when a key is pressed BIT 5 is set to 1 ...Bit of fun Part Two - CPU SwapFollowing on from [url="https://worldofspectrum.org/forums/discussion/56671/bit-of-fun-one-change-only/"]this topic[/url], I felt given the erm 'natu…
... ://worldofspectrum.org/forums/discussion/56671/bit-of-fun-one-change-only ... a 6502 instead of a Z80, allowing for the other surrounding ... I suspect each CPU type (Z80 vs 6502) they both have ...New Utility to Transfer Z80 Snapshot to +3 DiskSince getting a Gotek for my +3 it has been my go to machine. The biggest downside however is the lack of older games on disk format with pretty much…
... utility currently utilises the popular z80 format (v1, v2 or ... registers as defined in the z80 snapshot. You can even ... is much better than z80 compression but it could ... often crashing. After a bit of messing about I found ... the utility needs a bit of a tidy up ...ZEsarUX Beta 8.1Hi! I have uploaded a new ZEsarUX 8.1 BETA version. You can download compiled versions for Windows, Mac, and the source code from: https://gith…
... my computer
-added 1-bit tile mode
... when paging was disabled by bit DI7FFD
Fixed average ... /> Fixed loading and saving +3 .z80 snapshots
Fixed placing menu ... on ZXSpectr. It fixes return flags when using tape traps.
ZEsarUX 8.1 stableHi! I've uploaded a new ZEsarUX 8.1 stable version. Go to the github released webpage to download it: https://github.com/chernandezba/zesaru…
... tbblue register 63H: copper 16 bit write
-added tbblue ... when paging was disabled by bit DI7FFD
Fixed average ... /> Fixed loading and saving +3 .z80 snapshots
Fixed placing menu ...
Fixed bug on return flags from tape load trap. 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…
... a small error above. The Z80 doesn't use signed binary ... will be 1 (as bit 7 has changed from 0 ... add 20 to a 16 bit register with a value ... of individual instructions on the flags. If you want a reasonable ... needs to include the "undocumented" flags (bits 3 and 5) ...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…
... always true? If the Z80 uses two's complement ... that the bit patterns are consistant and the flags are ... head around how the z80 deals with binary numbers ... [/quote]
The Z80 doesn't care - only humans ... bits mean. All the Z80 is doing is applying ...ADCI'm a little confused about how the Z80 manages the ADC instruction. I'm assuming two ADD instructions are performed (am I wrong?!) I can think of 3 …
... an 8-bit adder (as in a z80 8-bit add instruction ... up with the least significant bit on the right and ... Cin of the least significant bit (A0/B0) are left ... Cin for the least significant bit (the full adder for ... sets Carry and Half-Carry flags fine but how is ...MEMPTR finally crackedThis post is mainly for emulator developers. As you may be well know there is a misterious internal register in Z80 CPU (MEMPTR) which value is set …
... a misterious internal register in Z80 CPU (MEMPTR) which value is ... set or changed by some Z80 instructions and 2 bits of ... 5 of the Flags register after the instruction BIT n,(HL). But ... was not exactly known which Z80 instructions initialize the MEMPTR and ...Sprite adviceHello. So, I'm slowly getting to grips with Z80 assembly - currently equal parts frustration and enjoyment. Now looking for some advice to help shift…
...
; them to Z80.
; My generators ... acceptable on
; Z80. Their advantage was their small ... quite a gonzo-routine on Z80. This
; ... entry.
; 16-bit seed random generator
; ----------------------------< ...The new GP2Xpectrum releases threadYeah, I know the thread title isn't exactly too original, but I've decided that just one post to hold all updates makes more sense than a lot of smal…
... Software/Z80/Exerciser/Spectrum/]Z80 Exerciser[/URL], and fixed several flags bugs ... even a bug loading the z80 file from that page. ... bug when loading some .z80 files with version 1.45 ... .
- Fixed flags behaviour for several instructions: BIT*, CPI, SBC & ...ZXSpin 0.61 Available nowHi all! Well, after a lengthy few testing cycles, I'm taking the plunge and uploading the latest version of ZXSpin, to replace the rather aged old 0…
According to the [URL=http://www.mdfs.net/Software/Z80/Exerciser/Spectrum/]Z80 Exerciser[/URL], some flags are wrong.
The failed tests are:
hl,
add hl,
add ix,
add iy,
bit n,ZXSpin 0.61 Available nowHi all! Well, after a lengthy few testing cycles, I'm taking the plunge and uploading the latest version of ZXSpin, to replace the rather aged old 0…
... .mdfs.net/Software/Z80/Exerciser/Spectrum/]Z80 Exerciser[/URL], some flags are wrong ... ix,
add iy,
bit n,
[/QUOTE]
ZXSpin 0.61 Available nowHi all! Well, after a lengthy few testing cycles, I'm taking the plunge and uploading the latest version of ZXSpin, to replace the rather aged old 0…
... ://www.mdfs.net/Software/Z80/Exerciser/Spectrum/outall.txt[/ ... just flag effects. The .z80 file is in 48k mode ... /> hl,
bit n,(+1)
bit n,
cpi< ... them thanks to The Undocumented Z80 Documented, by Sean Young ... out to be related to flags 5 and 3, so ...ZXSpin 0.61 Available nowHi all! Well, after a lengthy few testing cycles, I'm taking the plunge and uploading the latest version of ZXSpin, to replace the rather aged old 0…
... =Dunny]Well, as MEMPTR *is* flags 5+3, I'd say ... /> MEMPTR is flags 5+3 for the instruction BIT n,(HL) , so ... Z80 Exerciser to be an interesting way to find bugs in flags ...My emulator doesn't take "commands"Hi This is probably a question that is very hard to answer, but perhaps some of you have/had the same problem. In my own emulator (that I have built)…
... a problem, The BIT instruction how does it handle flags?
I ... .
The question is actually bit 3 and 5, what should ... figure out I dont touch bit 2 and 5 at all ... here.
[url]http://www.z80.info/z80href.txt[/url]My emulator doesn't take "commands"Hi This is probably a question that is very hard to answer, but perhaps some of you have/had the same problem. In my own emulator (that I have built)…
... a problem, The BIT instruction how does it handle flags?
I ... to have changed during the z80's lifetime as it has ... />
[url]http://www.z80.info/zip/z80-documented.pdf[/url]
z80 versions, the internal memptr register and how it affects flags ...super-quick games in BASIC?do you think, games written in BASIC could run flawlessly at high speed when run in a speccy emulator at, say, 1000% speed? (i wonder, speccy is rare…
... =FrankT;208352]This is a bit of a co-incidence, just ... [I]Normal Speed[/I] type flags, via unused op-codes, then ... at the end of the Z80-CPU intensive routines, the [I ...Fuse for Mac OS X beta releasesA beta version of Fuse for Mac OS X has been released at the dedicated sourceforge project: [url]http://sourceforge.net/projects/fuse-for-macosx/[/u…
... Woodmass).
[*] Fix undocumented flags after BIT n,(IX+d) instructions (Philip ... the reset line on the Z80) and "hard" resets (pulling the ... Interface I state information to z80 and szx snapshots (Fredrick Meunier ...Bizarre stuff in Interface 1's shadow ROMAccording to the Complete Shadow ROM disassembly, the function that exits back to the BASIC interpreter after interpreting IF1 commands is this: [co…
... - BIT 7, (FLAGS) is not a valid Z80 instruction. You can only BIT a ... the instruction is:
BIT 7,(IY+1)
Bizarre stuff in Interface 1's shadow ROMAccording to the Complete Shadow ROM disassembly, the function that exits back to the BASIC interpreter after interpreting IF1 commands is this: [co…
... - BIT 7, (FLAGS) is not a valid Z80 instruction. You can only BIT a ... a few instances of invalid Z80 instructions. Presumably some assemblers recognise ...Emulator accuracy test?When I first created my emulator it worked fine. But then I found one or two games that had odd quirks. Eventually I found the flag or command that w…
... and check that all the flags and results are correct. It ... itself be altering flags - maybe set a screen memory bit so if ... good for flags:
[url]http://mdfs.net/Software/Z80/Exerciser/Spectrum ...48K games that don't work on a +2Not sure if there is already a thread about this but recently I've noticed some old 48K games will not run on my +2 - even in 48K mode. Examples are…
... /> When an interrupt occurred the Z80 would jump to $FFFF.
The Z80 would wrap-around to $0000 ... , I wonder if setting bit 4 of FLAGS (system variable at address ... .
7) Z80 timing differences. The Z80 in a 128 machine ...Bit 3 And Bit 5 Of The Flag RegisterHi, I know that bits 3 and 5 are "undocumented" but does anyone know where I can find data on how they are handled? For instance, it would seem th…
... 8-bit result of an instruction that changed the usual flags. This ... /nowind/?q=node/10]undocumented Z80 document[/url].
What ... http://scratchpad.wikia.com/wiki/Z80]Tech Info wiki page on ... the Z80[/url]. Basically, it just ...Integer RangesOK, I need a little help clarifying something. I am making good progress with the emulator so far - I've emulated most ADD, INC, DEC commands (as we…
... or overflow but the same bit patterns: 11111111 + 00000001[/code]< ... /> [/QUOTE]
The Z80 doesn't see any difference ... bit pattern. Whether or not the carry and/or overflow flags ... get set here depends on what Z80 instruction you ...InterruptsI need help emulating interrupts. My z80 core currently emulates all un-prefixed opcodes and the CB opcodes. I thought I would start on emulating co…
... not in the popular 8-bit computers), however, so failing ... maskable interrupt occurs, the z80 automatically disables further maskable interrupts ... the z80 does and implement the IFF1 and IFF2 flags to ... interrupts occur and the z80 responds in the different ...VIC 20 emulation on the SpectrumI'm sure most people are aware of the my attempt at bringing the full Commodore experience to Sinclair users with the "Twenty Commodes" program. It e…
... to writing a new virtual Z80 core as I have Nascom ... the 6502 flags (which the 6502 alters quite a bit). My core ...VIC 20 emulation on the SpectrumI'm sure most people are aware of the my attempt at bringing the full Commodore experience to Sinclair users with the "Twenty Commodes" program. It e…
... must admit it's a bit weird mixing the two and ... instead of JP when doing Z80 code...
I am ... idea for storing the 6502 flags, but I need to free ...
