amstrad/amstrad: MAME fails the majority of the SHAKER tests

[malespiaut]

MAME version

0.264 (unknown)

System information

OS: Arch Linux, 64-bit, kernel 6.8.5-zen1-1-zen
Locale: en_US.UTF-8
RAM: 16GB
CPU: 11th Gen Intel i7-1165G7 (8) @ 4.700GHz
GPU: Intel TigerLake-LP GT2 [Iris Xe Graphics]

INI configuration details

No response

Emulated system/software

Amstrad CPC6128 (cpc6128)

Incorrect behaviour

The SHAKER tests is an all-in-one floppy to test CPC emulator accuracy, developped by the demo group Logon System. It can be downloaded at https://shaker.logonsystem.eu/.

Most tests show graphical glitches, compared to actual “screen shot” of the tests running on actual hardware. All screen shots are listed at https://shaker.logonsystem.eu/tests

Expected behaviour

MAME should display the same graphical result as the screen shots of the tests running on actual hardware.

Steps to reproduce

1. Launch mamke for any CPC machine (cpc464, cpc6128, cpc464+, cp6128+, etc.)
2. Load the floppy shaker25.dsk on slot 1.
3. Type cat to list the content of the floppy. Or directly type run"shake25X (replace X with either a, b, c, or d).
4. Choose any test, and compare the result with what is shown at https://shaker.logonsystem.eu/tests (Note: For choices that have several tests, press SPACE to move to the next one. Some tests (i.e. VSYNC) can take time.)

Additional details

No response

[holub]

Amstrad is known for lacking accuracy in MAME.
Can you please use https://mametesters.org/ for such reports? At least all be stored in same place.

[angelosa]

Can you please use https://mametesters.org/ for such reports? At least all be stored in same place.

I disagree: sounds like a spike #10504 and #9106 , better suited with GH issues. I'll look at this at some point in future, putting labels as reminder.

[flexiworld]

I recommend that you read this technical article about the CRTC chips on CPCwiki:
https://www.cpcwiki.eu/index.php/CRTC

If MAME implemented everything described there, CPC emulation would improve a lot.