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  • Border art viewerRecently, we were working with diver/4d on border art. The idea was to push the techniques of drawing on the border to the limit and to see, how much…

    ... simplest way to tell the ULA 128s apart from the ASIC ... I/O. On the unmodified ULA machines all I/O is ... to go with the memory contention, because it also helps to ... of them have no memory contention at all).
    introspec introspec September 2013 Development
  • ZX Spectrum clock signals comparedI haven't searched for this on WoS; it might have been posted before. But I think it's important info, and can't do any harm to repeat or show from a…

    ... blackouts when the ULA stops it because of contention.

    Dylan ...
    mcleod_ideafix mcleod_ideafix September 2013 Hardware
  • ZX Spectrum clock signals comparedI haven't searched for this on WoS; it might have been posted before. But I think it's important info, and can't do any harm to repeat or show from a…

    ... z80 instructions.
    about the contention, the sd card clock follow ... blackouts when the ULA stops it because of contention.

    Dylan ...
    Mp Mp September 2013 Hardware
  • ZX Spectrum clock signals comparedI haven't searched for this on WoS; it might have been posted before. But I think it's important info, and can't do any harm to repeat or show from a…

    ... instructions.
    about the contention, the sd card clock ... missing bits because of the ULA contention.
    And using ... clock signal from the ULA.
    So what ... the clock signal from the ULA.
    With the ... the clock signal from the ULA.
    With the 1K ...
    bverstee bverstee September 2013 Hardware
  • CPU upgradethere's an FPGA accelerator for Amiga computers. would there be any benefit in upgrading ZX that way?

    ... into consideration memory contention when the CPU and ULA both want to ...
    JeffB JeffB September 2013 Hardware
  • display file addressing; screen slicingWhile working on this Compendium I'm updating or rewriting a lot of stuff. One thing I eventually came to appreciate was the simple & clever way in w…

    ... />
    Contention is a delay that occurs when the ULA has to ... few T-States so the ULA can do its job. This ... occurs when the z80 and ULA are working on the same ... /> BASin doesn't apply any contention (it makes no real difference ...
    Dunny Dunny October 2013 Sinclair Basic
  • LOOK at the size of my Rom/EmulatorOk, we have 16k, 48k, 128k, even a 256 odd k Rom/Emulator But I want more :p Is there anything out there now or been worked on to give more, as the…

    ... doohickie referred to as [timing] "contention" all aboot, eh?
    < ... hardware).

    Can contention be done away with in ... br />
    Contention is due to the fact the ULA and the ... emulators can do away with contention, in fact most emulators ( ...
    rich_chandler rich_chandler October 2013 Sinclair Miscellaneous
  • Two more faulty onesCould I get your opinion on these two faults, please? Understanding these two cases would be very beneficial for my ZX education. Thanks! - A Spectr…

    ... ]
    The ULA cleaned up the earlier I/O contention fixes that ... had been applied to the issue 2 5C112E ULA ... =1]Chapter 24. ULA Versions, section "Issue 3 ULA 6C001E-6", p ...
    balford balford November 2013 Hardware
  • Overclock the Z80 cpu to smooth out gameplay?Was thinking today of a Genesis/Megadrive mod I did a while back. It involved lifting the CLK leg on the motorola 68000 cpu (which in the MD, if I r…

    ... bottle neck? ...CPU, RAM speed, ULA?[/QUOTE]

    Usually the ... ULA. More sprites = more writes to ... the Pentagon which has no contention in shared RAM.
    chev chev November 2013 Hardware
  • Interesting 48K failureI thought I'd recount a failure I've not seen mentioned before that I saw tonight while fixing a 48K issue 6 board. The background: The initial fail…

    ... ) are not affected by the ULA contention. I refer interested readers to ...
    1024MAK 1024MAK December 2013 Hardware
  • 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…

    ... /> [QUOTE]
    The ULA is responsible for generating the ... it cancels the contention with the rising ... state T1. This "contention off" mode persists until ... be ignored by the ULA contention handler as it ... described above, the ULA dynamic memory handler will ...
    antoniovillena antoniovillena January 2014 Development
  • Port $28FF. Why 28?Testing floating bus behaviour for ZXUno, I've found that both Cobra and Arkanoid use this specific 16-bit port: $28FF. What is so special about putt…

    Might be an I/O contention workaround.

    [quote="48K ... range 0x4000 to 0x7fff, the ULA treats this as an attempted ...
    Hikaru Hikaru February 2014 Hardware
  • 48k+ ULA'sI've got three ULA's here that only work in certain boards. Thought I was going nuts, swapping, changing stuff around. But hey, I've got two working …

    ... versions of the Spectrum 48K ULA:

    [LIST]
    [*] ... 5C102E: Original ULA, found on Issue 1 and ... boards. Have a I/O contention fault that necessitates the 'dead ... CPU in machines containing this ULA (Issue 2 boards).
    ...
    balford balford March 2014 Hardware
  • New test for finding missing +2A/+3 ULA timing detailsHello, having added the +2A/+3 emulation recently, I want to make sure I got the ULA timing 100% right. We know when the contention pattern starts, …

    ... attribute fetch goes unnoticed and ULA always fetches the pixels from ... differences, or because the +3 ULA intentionally delays the flip, or ... different way how the +3 ULA prepares the screen address on ... not really needed for the contention, it is perhaps just an ...
    Patrik Rak Patrik Rak March 2014 Emulators
  • New test for finding missing +2A/+3 ULA timing detailsHello, having added the +2A/+3 emulation recently, I want to make sure I got the ULA timing 100% right. We know when the contention pattern starts, …

    ... intended duration which the 128K ULA generates - we know for sure ... 32 in case of 48K ULA, but I have seen a ... ptime version with the 128k contention change added? The tap should ... interrupt and thus skewed by contention for some other reason (for ...
    Patrik Rak Patrik Rak March 2014 Emulators
  • 48k+ ULA'sI've got three ULA's here that only work in certain boards. Thought I was going nuts, swapping, changing stuff around. But hey, I've got two working …

    ... versions of the Spectrum 48K ULA:

    [LIST]
    [*] ... 5C102E: Original ULA, found on Issue 1 and ... boards. Have a I/O contention fault that necessitates the 'dead ... CPU in machines containing this ULA (Issue 2 boards).
    ...
    bverstee bverstee March 2014 Hardware
  • JP (HL) confusionokay.... JP nn will jump to memory address nn. JP (HL) ,I assumed would read the contents of memory address HL and jump to the location and be a gre…

    ... ), we have the entertaining memory contention heaavily affecting register-pair operations ... 't too slow when the ULA isn't drawing the screen ...
    zub zub March 2014 Development
  • Totally random idea for the hardware nuts to exploreWhen it comes to multi-player games, how hard would it be to generate a second display from a single Speccy, instead of trying to link up machines, s…

    ... just leaving the video circuits, ULA and the "lower" DRAM ... is accessed by the ULA is contended, if ... piggy back the second ULA on the original but ... to worry about conflicting contention because that whole 16k ...
    Also 2 piggybacked ULA's would generate a lot ...
    Basher Basher April 2014 Hardware
  • Totally random idea for the hardware nuts to exploreWhen it comes to multi-player games, how hard would it be to generate a second display from a single Speccy, instead of trying to link up machines, s…

    ... chip that just emulates the ULA and external RAM is one ... , become contended - would the external ULA/RAM setup be able to ... of the ROM. Could read contention be avoided, such that the ...
    joefish joefish April 2014 Hardware
  • Totally random idea for the hardware nuts to exploreWhen it comes to multi-player games, how hard would it be to generate a second display from a single Speccy, instead of trying to link up machines, s…

    ... contention.
    The tricky bit, is if you use a Sinclair ULA ... relevant RAM. As the internal ULA normally supply the CPU clock ...
    1024MAK 1024MAK April 2014 Hardware
  • Space Harrier new loading screenHi, The original screen: [IMG]https://dl.dropboxusercontent.com/u/2616449/spectrum/SpaceHarrier.png[/IMG] and my new version: [IMG]https://dl.dro…

    ... its 6 MHz Z80, memory contention affects the whole of RAM ... a version for the original ULA to go with the screenshot ...
    zub zub April 2014 Games
  • Double-Buffer ScreenFor my Alien Breed Speccy re-write I decided to use a Double Buffer (DB) or 'Back Screen' to draw all the game action onto, before shuffling the whol…

    Shove the DB screen above 32768 and any accesses to it will be quicker overall because there won't be contention with the ULA
    melkig1967 melkig1967 April 2014 Development
  • Fuse 1.1.1 releasedOn behalf of the Fuse team, I am pleased to announce the 1.1.1 release of Fuse. The changes from the recent 1.1.0 are relatively minor, mostly correc…

    ... ULAplus ports have the same contention as port #FE.[/QUOTE]
    ULA+ ports...

    Patrik
    Patrik Rak Patrik Rak May 2014 Emulators
  • Fuse 1.1.1 releasedOn behalf of the Fuse team, I am pleased to announce the 1.1.1 release of Fuse. The changes from the recent 1.1.0 are relatively minor, mostly correc…

    ... the contention as ULAplus is part of the ULA and the ULA is ... which doesn't contend the ULA+ ports...[/QUOTE]

    Well ... before we knew what the contention would be. Although Woody guessed ...
    chev chev May 2014 Emulators
  • Fuse 1.1.1 releasedOn behalf of the Fuse team, I am pleased to announce the 1.1.1 release of Fuse. The changes from the recent 1.1.0 are relatively minor, mostly correc…

    ... contention as ULAplus is part of the ULA and the ULA ... that, so ULA+ and ULA would have the same contention, regardless of ... it would mean bit more contention than necessary. Now it ... hardware replacements, each applying contention to some ports differently.
    Patrik Rak Patrik Rak May 2014 Emulators
  • Spectrum screen layoutSeeing the thread on displacement I was wondering why the spectrum had the stupid screen split into three sections and the addresses for each section…

    ... book, 'The ZX Spectrum ULA: How to Design a Microcomputer ... reads from memory whilst minimising contention (i.e. either a slowdown ... When drawing the screen, the ULA reads four bytes of memory ... addressing constraint imposed by the ULA and the DRAM refresh ...
    zub zub May 2014 Sinclair Miscellaneous
  • Fuse 1.1.1 releasedOn behalf of the Fuse team, I am pleased to announce the 1.1.1 release of Fuse. The changes from the recent 1.1.0 are relatively minor, mostly correc…

    ... that, so ULA+ and ULA would have the same contention, regardless of ... have the same contention as the ULA because it is ... hardware replacements, each applying contention to some ports differently.[/ ... the same ... it is the ULA contention.

    [quote] ...
    chev chev May 2014 Emulators
  • Fuse 1.1.1 releasedOn behalf of the Fuse team, I am pleased to announce the 1.1.1 release of Fuse. The changes from the recent 1.1.0 are relatively minor, mostly correc…

    ... but have the same contention as the ULA because it is the ... />
    Well, original ULA applies 4 different IO contention patterns, see [URL ... the same ... it is the ULA contention.[/QUOTE]

    Perhaps I ...
    Patrik Rak Patrik Rak May 2014 Emulators
<1…11121314151617…34>

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