06772: Dragon machines run too fast!

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
06772	Gameplay	Major	Always	Nov 22, 2017, 20:31	Nov 23, 2017, 14:42

Tester	MrGW	View Status	Public	Platform	MAME (Self-compiled)
Assigned To	hap	Resolution	Fixed	OS	Linux (64-bit)
Status [?]	Resolved			Driver	technos/ddragon.cpp
Version	0.191	Fixed in Version	0.192	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	06772: Dragon machines run too fast!
Description	Best guess is this in dragon.cpp: static MACHINE_CONFIG_START( dragon_base ) MCFG_DEVICE_MODIFY(":") MCFG_DEVICE_CLOCK(XTAL_4_433619MHz) // basic machine hardware MCFG_CPU_ADD("maincpu", M6809E, DERIVED_CLOCK(1, 1)) My MAME-fu is poor, but looks like CPU clock being derived from PAL colour subcarrier frequency. Of course, CPU rate should be a subdivision of SAM rate depending on its settings as per CoCo.
Steps To Reproduce	Reproduce by just running anything on a dragon32 or dragon64.
Additional Information	Ciaran Anscomb (XRoar author) discovered this issue and provided his initial analysis of what he believes is causing the issue.
Github Commit

Flags	Verified with Original
Regression Version
Affected Sets / Systems

Attached Files

No.14458 hap Developer Nov 22, 2017, 22:20	It looks like the motherboard has 2 XTALs: 4.443619MHz(PAL subcarrier), and 14.2180MHz(main). Pippin(Dragon prototype) and the 1st version of Dragon 32 Mark I have a 14.31818MHz main XTAL instead. MAME doesn't emulate these machines(yet?). 2nd version of Dragon 32 Mark I, Mark II, and every other Dragon after that, has a 14.2180MHz main XTAL. photos here: http://archive.worldofdragon.org/index.php?title=Motherboard_Pictures
No.14459 hap Developer Nov 22, 2017, 22:34 edited on: Nov 22, 2017, 22:35	It's fixed now. Note: don't be misled by MAME's reported CPU speed of 3.55MHz. The M6809E has an internal /4 divider, making the practical CPU speed 0.89MHz.
No.14464 MrGW Tester Nov 23, 2017, 14:42	Thanks for fixing this one too, hap!!