CSpect:known bugs

CSpect V2.19.0.3

• intentional for performance reasons:
  • sprites: the collision bit is not implemented
  • sprites rendering is not one-scanline-buffer delayed and all changes in sprites affect current scanline
  • modifications to NextRegs done in copper propagate to rendering usually only once per scanline, the state for rendering is sampled after right border area (ahead of copper wait h=39), affecting previous line instead of next (palette changes, X/Y offsets, etc)
  • modifications to NextRegs done by CPU propagate to rendering usually only once per scanline, usually retroactively for whole current scanline
• major differences / missing features
  • blending modes: improved greatly in V2.19.0.3, blending only L2 priority colours wrongly.
  • NextZXOS streaming API doesn't work (the initialization of stream fails - rst 8 service 0x86 ; DISK_STRMSTART)
  • DMA: Zilog mode is not implemented (port 0x0B) (but zxnDMA does listen to both ports, so SW using 0x0B will get one byte shorter transfers)
• subtle differences
  • sprites: the wrap-around the 512x512 coordinate space is only partially implemented in extreme cases (relative sprite so far from anchor that x8 scale wraps it back onto screen)
  • NextReg $02 implementation of soft-reset does something, but not the same thing like HW
  • NextBASIC SPECTRUM command may load SNA file with wrong ROM paged in (very likely related to SW NMI trigger emulation nextreg 2,8 ROM2 $0aab)
  • NextZXOS browser is unable to load SNA/SNX/Z80 files in latest distribution (does work with older 3.1.5 core NextZXOS) (may be related to SW NMI)
  • More >> ZX80 and ZX81 modes reset and hangs on a black screen while launching the Paul Farrow emulators. (may be related to soft-reset)
  • More >> 128K BASIC launches but gets no keypresses on 2.19.0.2. On V2.16.6.0 it hangs on a black screen and border. (may be related to soft-reset)
  • DMA: reading-registers are a bit off (for example status bit5+0 not reset correctly after LOAD, probably few more (but core 3.1.5 also reads bit0 wrongly, so always test own code with all target platforms))
  • NextRegs $09, $34, $41, $8E read incorrectly (reads after certain writes produce wrong value) (but also the test is checking 3.1.5 behaviour, needs update to 3.1.10)
  • debugger: the step-over F8 does run interrupt handler every 16-20ms (as part of debug-live-screen-view drawing), so it's almost after every F8 press
  • Z80: di : halt doesn't put CPU in infinite loop waiting for NMI, but proceeds further
  • Z80: block of prefixes/instructions 0xDD/0xFD/EI does not inhibit masked interrupts
• recently fixed:
  • CTC timing is affected by the Z80N clock speed. It should be using a constant 28Mhz reference clock.
  • vertical ULA clipping is not working in Timex modes
  • ULA scroll and half-width scroll is not implemented in Timex modes
  • Z80: when masked interrupt handler is entered, the interrupts remain enabled (IFF1=1, IFF2=1)
  • divMMC automap-enabled traps certain addresses even when RAM is mapped to MMU0/MMU1
  • something not completely right about Enhanced ULA colours (test TFalBUla.sna)
  • F3 reset does not autodetect NextZXOS 2.06 vs 2.07 when running with card-image, so 2.06 image ends with purple stripes.
  • some NextRegs read as zero until they are written into first (quick-boot mode with SNA file without full NextZXOS image)
  • Layer2 640x256x4bpp clipping is broken (V2.19.0.3 does fix this correctly, was still broken before)

not verified in V2.19.0.3 (but known bugs of older versions, may be still present):

• CTC time constant of 0 causes incorrect code execution.
• the initial file-import sequence of CP/M BIOS fails. (get cpm-a.p3d file from somebody with a working clean CP/M installation and copy that into c:/NextZXOS, or use other emulator to create the file)
• default ULA palette after power on (quick boot without NextZXOS) is slightly different
• (should be improved now, to be tested) without the full NextZXOS card image the esxdos services are provided by open source CSpect plugins, the implementation is limited and crude - some of the returned values are incorrect/etc, but loading files works.
• direct loading of NEX files does not support all combinations of loading-screen type and palette on/off (but V2.12.9 does load more files than V2.12.5, all common ones should work)
• sprites: something something about default clipping... just set clip windows explicitly in your SW.
• sprites: clipping in non-over-border configuration is maybe wrong (probably fixed in 2.19.0.3, needs more testing)
• fixed by V2.19.0.3 stencil mode is not implemented, needs more testing

Platform Specific (may be already fixed):

• Mac: Mouse does not work / behaves erratically
• Mac: after launch keyboard being irresponsive - try "alt+tab" to other app and back
• Linux: (some/all?) plugin windows like nextregisters (ctrl+alt+r) does not refresh while in debugger
• Linux: (some/all?) plugin windows like nextregisters (ctrl+alt+r) does draw hover-hint tooltip only for one frame, then it becomes invisible

Not a bug:

• CSpect works with "-sound" (does switch sounds OFF), but shows only black screen without it:
  • you forgot to install OpenAL, check the ReadMe.txt of the emulator.