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Hell no. This is a set of extremely specialized workarounds for how the Spectrum ULA works. The Amstrad's graphics work more like PC CGA.

Hi again!

Here is my 4th attempt:
diff 4th attempt

specz80_device is now derived from the main z80_device class. I must admit that with specz80_device containing all my mods things do seem to look a lot neater. Hope it is what you had in mind

It's definitely better. Would it be possible to actually put the specz80_device into a separate file? It has a lot of long comments, which is good for explaining how it works but kind of a pain for people just looking at the Z80.

No worries, was thinking the same thing, back soon

nice progress.
there is one more good test case - Qarx game http://www.worldofspectrum.org/infoseekid.cgi?id=0003960
it's high score screen have nice text scroll on border and multicolor effects

MetalliC - I've tried Qarx and everything looks good when viewing the hi-scores except for some strange artifacts at very top left of the border (See Qarx screenshot (Blue arrow pointing to the problem)). I'm confused as to why I am seeing these artifacts as I thought I had the border timings sorted. I've just gone into my loft and dug out my old 48K+ and +2 as I’d like to see how various games/demos/ULATestPrograms run on original hardware in comparison to mame (I’ve found screenshots of other Speccy Emulators running ULA test software on the web, but they all seem to give slightly conflicting results, so I’m not sure what I should trust). I shall post my screenshots and findings

Wow, after 20years+ they worked first time! I ran many different Games/Demos/TestTools on both machines. Here are my screenshots:

ZX 48+ testing

ZX 128+2 testing

Notes:
- On my 48k when running DarkStar, I repeatedly toggled between the menu and hiscore table. The border pattern was mostly in the same place where the yellow border section would begin/align just after the 'k' of the "Dark Star" title. Except for about 1 in 10 times where The yellow border section would begin/align just after the first 'a' of the "Dark Star" title. On my 128k, although the border pattern is naturally skewed, it is always in the same place regardless of how many times I toggle between menu and hiscores. Screenshots of all these scenarios can be found in the albums above.

- Qarx hiscore screen looks perfect on my 48k (No strange artifacts at the very left side of the border). However, the border width of my actual 48k is noticeably thinner than mame's. Just a hunch at the moment, but I suspect that mame is showing more (too much) border than was actually possible back in the day and that is why I am seeing the strange artifacts. Searching on the web for other peoples screenshots of actual spectrums running and their border width looks the same as mine (So I do not think its just my 48k that has an unusually thin border). Also, it appears mame shows more border than the other spectrum emulators I've tried (Emuzwin/fuse), which is interesting.

- The Contended memory / floating bus test problems I found here Speccy tests
btime.tap (border time test) and stime.tap (screen time test) draw a small red line either in the border section or the screen section of the display. Where it is drawn depends on when the opcode writes (that set the red border/screen colour on and then off) occur. Using the 'q' and 'a' keys, you are able to adjust the timing of when the opcode writes occur, thus effect where the red line appears. I took plenty of screenshots when running btime and stime for various tstates.

Next step is to make sure these test results tally up with my mame mods

Those border and screen time tests look interesting. Thanks for the pictures

After fixing a few bugs (IO Contention wasn't working, and my floating bus timing and border positioning were a few tstates out) all the tests when running mame give the same results as my actual spectrums.

For completeness, here are some screenshots of the tests running on mame:
mame spec48 tests

mame spec128 tests

I'll post my latest diff shortly

I'd just did a quick 48k border comparison that gives some idea how much larger mame's border is compared by my actual 48k+. It does imply those Qarx border artifacts would just never been seen on actual hardware. Its not really a massive problem as you can use mame's slider controls (Screen Horiz/Vert stretch/Position) to achieve the desired look.

spec48k border comparison