00040: 720: About hacky sound CPU speed.

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
00040	Misc.	Minor	Have not tried	Jan 16, 2008, 09:09	Jan 18, 2008, 07:06

Tester	Tafoid	View Status	Public	Platform
Assigned To		Resolution	Fixed	OS
Status [?]	Resolved			Driver	atari/atarisy2.cpp
Version	0.122u2	Fixed in Version	0.122u5	Build
		Fixed in Git Commit		Github Pull Request #

Summary	00040: 720: About hacky sound CPU speed.
Description	I've noticed the z80 (sound cpu)'s speed is elevated for the 720 sets (720, 720g, 720gr1, 720r1, 720r2, 720r3) compared to others in the driver. The driver has a note mentioning: "artificially high to prevent deadlock at startup" and putting this at 2.2mhz instead of the driver base of 1.789772mhz. I was curious to see if the problem still existed (also, it seemed kind of hacky to raise the CPU above normal to make something work) so I rebuilt a MAME with the CPU speed for 720 back at the driver standard 1.789772mhz. I fired up 720 and noticed a black screen, consistent to the "deadlock" mentioned. So, I went to the Dip menu and activated Service Mode. You know what? It came up! I cycled the Service Mode and all items seemed to work fine. I turned the Service DIP back off - and the game booted and seem to play as intended. Subsequent starting of 720 seems to work fine @ default atarisy2 clock speeds provided there was an NVRAM present. Not sure if this game actually requires it's NVRAM full before booting, but it seems that way.
Steps To Reproduce
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	720

Attached Files