-
Question about CP Z80 instructionSorry if this is the wrong folder, but it seems the most appropriate. When performing a CP instruction, is the P flag set when the compared values …
... flag means parity/overflow. Generally in shift instructions it means parity (1 if ... instructions it means overflow.
An overflow occurs when you ... and hence there is an overflow.
As 3 ... then you'd have an overflow as -127-3 = -130, ... -
Question about CP Z80 instructionSorry if this is the wrong folder, but it seems the most appropriate. When performing a CP instruction, is the P flag set when the compared values …
Forget about the parity/overflow thing since your not JP PE or JP POing ;) -
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…
... br /> With regards to the overflow flag - would it be ... For instance, 255 + 5 = 5 + ?overflow + ?carry
[/quote]
overflow.
Overflow is when, using ... by instructions that use the parity/overflow flag to indicate it.
Sabre Wulf - don't you just hate itThere's lots of Speccy opinions that divide us, but one thing I seem to stand alone in is my dislike for Sabre Wulf. I'm not joking now, I don't like…
... the flags register is tested (parity/overflow bit is erroneously tested IIRC ...Sabre Wulf - don't you just hate itThere's lots of Speccy opinions that divide us, but one thing I seem to stand alone in is my dislike for Sabre Wulf. I'm not joking now, I don't like…
... the flags register is tested (parity/overflow bit is erroneously tested IIRC ...Tap file creation, parity error.Hi, I didn't know where to post this question so I've put it here :) I'm writing a program to convert an ascii file into a Spectrum .tap file (yes,…
... Soft taputils there is a parity error within the data block ... , the header parity is ok.
None ...Parity ErrorsJust checked my entire collection of TZXs (mostly from WoS) for parity errors - found a few things I wanted to share: "Bubble Bobble" Odd one here!…
... TZXs (mostly from WoS) for parity errors - found a few things ... here! The original TZX contains parity errors before the BleepLoad blocks ... /> The original TZX has 2 parity errors - blocks 1 & ... />
The following games have parity errors in at least 1 ...Quick method of fixing TAP parity byte?Quick question: are there any DOS/Win32 utilities (or at least, something in C/++ I could compile in Windows) which fix the broken parity byte of the…
... Windows) which fix the broken parity byte of the blocks in ...Overflow Flag QuestionHello all, After a long hiatus (lost all code when my MacBook was stolen) i've gone back to the drawing board and am writing a Z80 emulator in REALb…
... have a question about the overflow flag.
I am ... 0x0050. This means that my overflow flag is being set when ...Q on overflow on subtraction of 2 numbers.I came across this bit of code (paraphrased for clarity) that set the overflow flag on subtracting two numbers: result = A - B; overflow = (((A ^ B)…
... for clarity) that set the overflow flag on subtracting two numbers ... />
result = A - B;
overflow = (((A ^ B) & (A ^ result ... is used to calculate the overflow result above. Could someone explain ...Overflow Detection while Scanning a Number from a StringI've got some strange behaviour from a subroutine that reads a number from a string and converts it to a 32-bit long. It's C's strtol if it helps to…
... but C99 requires detection of overflow so I am using a ... *base does not cause unsigned overflow (meaning carry out of the ... result+=digit can't cause overflow following this multiply (ie there ...Help me with this Stack overflow Freak Show.I am asking a simple question on Stack overflow and once again, the closed minded morons a pointing and tutting. I'm asking a question about C point…
... a simple question on Stack overflow and once again, the closed ...TAPlist - the emulator versionI've got this working reasonably well; there's just a couple of small extra features which I want to add. (Recall that TAPlist writes a formatted lis…
... the next text fragment would overflow the buffer the file as ... leading type byte & trailing parity byte written by the ROM ...Overflow Flag QuestionHello all, After a long hiatus (lost all code when my MacBook was stolen) i've gone back to the drawing board and am writing a Z80 emulator in REALb…
Figured it out!
It turns out that DAA uses the P/V flag as a parity flag NOT an overflow flag! Stupid Rodeny Zaks - I wish it had been more clear!
MadDoc,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…
... I discovered was that the overflow flag was wrong when doing ... right result ($99), but the overflow flag was wrong. It turns ... the P/V flag as parity! I have now got around ...Thinking in Assembly (first efforts)The following is one small routine to educate myself on a few concepts (jumps, flow control, routines, CPI): [code]searchmem xor a …
... me the effect of the parity flag here. My readings so ... in the context of a parity or overflow flag depending on the ...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…
... flag is treated as a parity flag during NEG instruction, according ... 's document it's an overflow flag.
Two last ...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…
... subtraction)? Carry, half carry and overflow flags during subtraction are affected ... flag is treated as a parity flag during NEG instruction, ... It's treated as an overflow flag (which is consistent with ... where the increment causes an overflow into the top bit.< ...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…
... /pe,lp ; 10T Yup, the parity bit is the EAR bit ... repeat
call po/pe,overflow
exit:
pop hl ...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…
... /pe,lp ; 10T Yup, the parity bit is the EAR bit ... me to (ab)use the parity flag in that way; though ... it) and thus alter the parity? Is there a way of ... repeat
call po/pe,overflow
exit:
pop hl ...Assembler code from tutorial, problem!I was wondering if anyone could help me decipher this z80 assembler code? ORG 60000 LOAD 60000 EA60 21BCEA LD …
... up and into
this overflow byte or something??? I am ...Need help with my P flag!Not sure if I've emulated the P flag correctly when its comes to overflows. Here's what I've done: LD A,123 LD B,16 ADD A,B Twos Complement of 123 …
... higher than 127, causing an overflow and setting P.
If ...
-126 would caused an overflow as it passes
-128 ... sure I've done the overflow flag right.
Thanks ...Need help with denied Prince ClumsyI'm trying to create a TZX from my original Prince Clumsy tape. (I'm using an old walkman (only tape player in the house!), goldwave and maketzx). T…
... />
Block Size DataCRC Flag Parity PauseAfter
1 19 37DE9A84 ...Running Man problems1] The TZX doesn't have side 2 - the levels! 2] The TZX contains nothing but standard data blocks and loads instantly just like a TAP file. But in t…
... of the data and the parity byte has been altered correctly ...Codies help? Werewolves of LondonHi All, never one for shying away from the deep end, having only just dipped my toe in to the world of machine code I find myself trying to find out …
... at all.
Buffer overflow maybe? The code doesn't ...SimCoupe 1.0 released[size=-2](for those of you that don't read CSS)[/size] SimCoupe, the SAM Coup? emulator, has been updated to version 1.0. This major release adds ma…
... failing to set carry for overflow, or H flag
- Fixed ...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…
... by working out if an overflow has occured or not. Is ...RZX reference samplesJust wondering, is it ok that neither Spin nor Spectaculator can replay the RZX reference samples provided on the [URL="http://www.ramsoft.bbk.org/rz…
... , reporting identical IN underflow or overflow errors. The samples can't ...16-Bit Binary MathsHi, I'm trying to figure a few things out regarding 16-bit maths (SBC HL, ss in particular). regHL is an UInt16 (unsigned 16-bit integer) in my emu…
... byte3Sign 0 ) then
// Overflow
SetPVFlag()
elseif ( ... br /> else
// No overflow
UnsetPVFlag()
end ... br /> else
// No overflow
UnsetPVFlag()
end ...
