-
The I register pointing to $40–$7f causes ULA snow and a crash. Or does it?I have heard it from numerous sources, including a few members of this forum, that 128K/+2 machines crash if the I register points to a range of $40–…
... 2 machines crash if the I register points to a range of ... $40–$7f. I have been trying to reproduce ... to no avail. I get the ULA snow, sure thing, but ... that’s just it. I’ve ... a crash?
I’ve been using variations of ... -
The I register and IM 1Hi al! I've been doing some coding, replacing the BASIC ROM with my own code and upon examination of a few 16Kb cartridges, all the ones I've look…
Hi al!
I've been doing some coding, ... 16Kb cartridges, all the ones I've looked at have something ... a,63
ld i,a
im 1
I register, apart from its use in ... -
Snow on screen of 48K Speccyok you wizards I fixed up my 4116 ram issue as Winston and McLeod advised me before by replacing with 4164's.... all I could find here in Singapore (…
... with 4164's.... all I could find here in Singapore ... work fine. I also broke the crystal (I think 14MHz) ... bugging me since I got it working. Snow on the screen ... time. it's not the I register or the tuning - as ... .no-ip.com/speccy-pics/snow.jpg[/url]
... -
ULA bug and snowI am tryng to improve the snow emulation in FBZX wii but I do not have a real spectrum to test the results. I used the information taken from Harele…
... to improve the snow emulation in FBZX wii but I do not ... writing in the ULA video register the second screen byte it ... fetch cycle and if the I register is between 0x40 and x7F ... byte the value of R register.
This emualtes the ... -
Interrupts, 16k Spectrums and snowI'm writing something for the 16k Spectrum and I want to use interrupts. The avilable documentation doesn't seem clear enough for me to figure out ho…
... problem is ULA snow. Snow appears if the I register points to ... only place I can use. But does snow happen on ... a 16k Speccy? I'm assuming ... .
If snow _is_ a problem on 16k ... for me though. Occasionally I run a piece of ... -
ULA snow effectIt's wintertime, you know. [quote="http://ramsoft.bbk.org.omegahg.com/floatingbus.html"]when the I register falls in the range 0x40-0x7F then the UL…
... floatingbus.html"]when the I register falls in the range ... A7-A0 = the R register of the Z80
< ... - only works in SpecEmu I believe. This was put ... .
Things I don't understand:
... affected
- (....I [i]think[/i] I once borked up the ... -
Is spectaculator emulating the +2 correctly?i remembera few games that would crash when running in 128K mode, due to a bug in the hardware of the grey +2, hence it being replaced with the +2a. …
The 'snow bug' in the ULA is ... including the +2.
I read somewhere that it doesn ... is activated by setting the I register below 0x80 and above 0x3f ... check whether or not the I register is in that range with ... -
Is spectaculator emulating the +2 correctly?i remembera few games that would crash when running in 128K mode, due to a bug in the hardware of the grey +2, hence it being replaced with the +2a. …
[quote]
On 2003-08-08 00:18, needlej wrote:
(Woody - I couldn't get SPIN to reproduce this even with 'emulate ULA snow' turned on?)
[/quote]
GFX.SnowEffect := (Registers.I >= 64) and (Registers.I -
Is spectaculator emulating the +2 correctly?i remembera few games that would crash when running in 128K mode, due to a bug in the hardware of the grey +2, hence it being replaced with the +2a. …
... coding the effect when the I register pointed to any contended page ... only executes on a LD I,A opcode.
Besides ... , even with I set to $7e, I got no snow on my test ... -
RealXThis may be a dumb question but will RealX ever get released?
... values of the I register and the R Register, combined to form ... applied during this period is "snow contention".
... do with clarification - as snow contention is not applied ... cases.
Your Snow documentation also states incorrectly that ... -
Contention and floating bus timingHello, I was recently playing a bit with memory contention and floating bus stuff in ZXDS and there is one thing which puzzles me a bit. It is the d…
... "Snow Effect" with particular values of the I register.
[I] ... as Patrik points out below.[/I]
[QUOTE ... .
[QUOTE]I already read this in your ... .[/QUOTE]
I don't take the table ... matter of fact - I point out that it ... -
Contention and floating bus timingHello, I was recently playing a bit with memory contention and floating bus stuff in ZXDS and there is one thing which puzzles me a bit. It is the d…
... get the "Snow Effect" with particular values of the I register.[/QUOTE]
In fact, I thought the snow effect ... ).
I wonder if the snow effect might be another ... ]
Oh, I see. I got it as that the ... -
ULA RAS, CAS cycles, refresh and "snow effect"Hello everyone. I have a question, does anyone observed timings of RAS and CAS generated from ULA? I think there may be answer to where the "snow ef…
... will show you how the snow effect works.
Basically ... the refresh cycle when the I register is at that magic range ... lower 16K and hence the snow.
Summay: ULA generates ... do not have this resistor. I am currently investigating this.
ULA RAS, CAS cycles, refresh and "snow effect"Hello everyone. I have a question, does anyone observed timings of RAS and CAS generated from ULA? I think there may be answer to where the "snow ef…
... read access, one bug -> snow effect)[/QUOTE]
I think that NEC4116 chips ... can I offer the following as proof that the snow effect ... only occurs when the I register is set to a ... br />
Sorry I had to rush that description ...Blizzard's Rift in Spinanyone else having trouble playing blizzard's rift in spin, the game loads ok, you can select controls, select a system to visit but when you select …
... set the I register in such a manner that would cause snow on ...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…
... br /> [I]On a side-note, I wonder if setting ... crash even in 48 mode?[/I]
3 ... but Short Circuit 128 as I mentioned earlier is another) ...
8 ) Writing to I/O ports. Some games seem ... game, but the 'snow' effect (setting I register between $40 and ...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…
... any game, but the 'snow' effect (setting I register between $40 and $ ... on a 48 machine. I'm not sure how + ... />
[/QUOTE]
I use a +2A with SE ... and I have never seen the snow effect occur ever. (I have ... to music on a game I used to have)
...Maze Mania - How did they do it?Hi, I was looking at the game "Maze Mania" by Hewson Consultants, written in 1989. The game can be downloaded from here [URL]http://www.worldofspec…
Now shall we start getting really clever and start scrolling screen areas around by simply using the I register and a few choice opcodes or maybe just leave it there for now. Yeah, let's leave it cos I really can't be arsed :D48K 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…
... any game, but the 'snow' effect (setting I register between $40 and $7F ... harmless on a 48 machine. I'm not sure how +3 ... 48K machine with the snow effect. But hey, I've only just ... machines aren't affected by I addressing contended memory at all ...Snow on screen of 48K Speccyok you wizards I fixed up my 4116 ram issue as Winston and McLeod advised me before by replacing with 4164's.... all I could find here in Singapore (…
... , and the "snow" is white... I have only ever set I register in contended ... ram on an emulator, but when I did ... issue would surely make black snow...
Which leads ... "loader respect" of all time - I think your pac-man "load ...just thinking about ...compo for zx 16k ? anyone ?
... about where to point the I register:
In ... 32768: doesn't exist. :-) I suppose if you tried it ... RAM: gives you ULA snow.
In the empty ... you a different offset. I don't know if ... broke on [i]some[/i] DivIDE interfaces on [i]some[/i] Spectrums.Games not compatible with real grey +2There are many threads about Spectrum+3/2A incompatibility issues but what about grey +2? I've found that games like Marauder and Skate Crazy don't w…
... the I register points to 64-127 then you get snow and ... 49152-65535, so setting the I register to 192-255 can also ... grey +2 models.
I haven't tried any of ... the real thing so, I don't know if they ... same problem (they have the I register set to 240).Games not compatible with real grey +2There are many threads about Spectrum+3/2A incompatibility issues but what about grey +2? I've found that games like Marauder and Skate Crazy don't w…
... the I register points to 64-127 then you get snow and any ... 49152-65535, so setting the I register to 192-255 can also ... models.
[/QUOTE]
I'm missing something here. Why ...Mr Do! ?Not exactly a new idea (at least twenty-seven years old now :-o), but how about a port of Mr Do! to the Spectrum? There was never an official one, ev…
... avoiding the need for horizontal scrolling. I'm undecided as to whether ... border.
I believe I can even get the two ... (the single-byte ones, with register operands) take 4 T-states ... instructions aren't affected by I-register contention, so it can use ...Mr Do! ?Not exactly a new idea (at least twenty-seven years old now :-o), but how about a port of Mr Do! to the Spectrum? There was never an official one, ev…
... avoiding the need for horizontal scrolling. I'm undecided as to whether ... border.
I believe I can even get the two ... the single-byte ones, with register operands) take 4 T-states ... instructions aren't affected by I-register contention, so it can use ...ula bookula book is here: [url]http://www.zxdesign.info/book/[/url] can i post sam coupe stuff here - she kind of is a speccy if you stuff the speccy rom i…
I think there is a lot ... ! :grin:
I think I used to think snow was a TV ... quirk but I long ago learned ... hard way that setting the I register to 40h-7Fh was not ... same value to the R register!
Yes! POTW ...Pretty CrashesTo make a 48K spectrum crash spectacularly and beautifully enter the following into basic. Also works on a 128k in 48k mode though not quite as prett…
... pointing the I register to the RAM will cause the ULA snow effect ...New Game! Maritrini, Freelance Monster SlayerAfter experiencing the sweet taste of success, Maritrini woke up one fine day in a mess of bed sheets and with the biggest hangover she could remembe…
... models don't suffer the snow effect. 48, 128k+ and ... emulators where I can test this snow effect? I've produced ... must be enabled at ). I think the latest ZXSpin versions ... only needs to set the I register (and table) for IM ... ).
PD: I see you've used FD ...Double Dragon Remake: The Development ThreadOk guy's, so this is the new thread that will be focusing on Jim Bagley's development of the Double Dragon remake that was first proposed by myself a…
Some quote about snow effect
[QUOTE]
... models don't suffer the snow effect. 48, 128k+ and +2 ... it (must be enabled at ). I think the latest ZXSpin versions ... only needs to set the I register (and table) for IM 2 ...Strange behaviour in real hardware but not in emulatorsWell, at least not in any emulator I've tried. I've been reported by fellow forum member Macc that both our Maritrini Monster Slayer and Retroworks'…
... are disabled.
ULA snow is (roughly) when the ULA ... that it's just the I register which causes the problem. Your ... problem, as long as the I register is not $40-$7F (or ... /> Ideally, you should change the I register to a safe value (making ...
