03724: mrdo: Incorrect XTALs cause for problems with refresh rate and game speed.

- As of 0.139u2, some drivers and options show "16-bit EEPROM set with 8-bit data". Check 4030.
- Haze is calling for mixing issues with *SINGLE* VDP games in toaplan2.c. Check 4044.

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[ View Source: mrdo.c ]

Category [?]

Severity [?]

Reproducibility

Date Submitted

Last Update

03724

Speed

Trivial

Always

2010-02-09 21:45

2010-02-10 21:47

Tester

Oliver_A

View Status

Public

Assigned To

Tafoid

Platform

Priority

normal

Resolution

Fixed

Status [?]

Resolved

Driver

mrdo.c

Projection

None

Version

0.136u2

ETA

None

Fixed in Version

0.136u3

Build

Summary

03724: mrdo: Incorrect XTALs cause for problems with refresh rate and game speed.

Description

The driver for Universal's Mr. Do has the wrong speed for the CPU, sound and screen refresh rate.

Reason: the schematics have the wrong crystal oscillator values.

Mr. Do uses 2 crystals, each for the video timing, and CPU / Sound speed.

In the schematics, the crystal for the video timing is 20Mhz and for the CPU/Sound 8Mhz, which is divided by 2.

On the real Mr. Do PCB (8201 revision), the values for the video timing is 19.6 Mhz and for the CPU / sound 8.2Mhz.

That means, the real values for the game are:

CPU: Z80 clocked at 4.1 Mhz.
Sound: 2*SN76489 clocked at 4.1 Mhz.

The change in the video oscillator frequency also affects the refresh rate.

Steps To Reproduce

Locate a real Mr. Do PCB and compare the oscillator frequencies with those of the schematics. On revision 8201 PCB, they will not match.

Additional Information

I have included 2 photos taken from my ORIGINAL Mr. Do PCB which verify my claims.

The board was not modified in any way. In fact, it would be quite hard to purchase the two oscillators, because the frequencies are so odd.

Note: this descripancy in clock speeds is most probably also responsible for the off-key music in Mr. Do Run Run.

Flags

Verified with Original

Regression Version

Affected Sets

mrdo

Old BugID

Attached Files

MrDo_PCB.zip (2,191,229 bytes) 2010-02-09 21:45

Relationships

Notes
(05677) Tafoid (Administrator) 2010-02-09 23:34 edited on: 2010-02-09 23:42	I can confirm that the music sounds a bit more accurate to recordings with the new xtal values. Thanks for the fine and clear pcb picture. Reworded the description slightly. These pictures are dated nearly 7 years ago - are they really that old?

(05678) Oliver_A (Tester) 2010-02-09 23:48	Hi Tafoid, no, they were taken a few minutes before I submitted the report. The 2003 date comes from my old digi cam, which resets the date every time I recharge the batteries. Thanks for the quick response.

(05696) Tafoid (Administrator) 2010-02-10 20:59 edited on: 2010-02-10 21:00	I'm applying this information to the driver for inclusion into MAME. Expect it to hit in 0.136u3. Another Dev was nice enough to pull his PCB out and it matches yours in model and xtals.

(05697) Oliver_A (Tester) 2010-02-10 21:44	Great! :D I would also try to check if the XTAL information for Mr. Do's Wild Ride, Mr. Do VS. Unicorns and Mr. Do Run Run have the same error. I read in another bug report that the sound in Mr. Do Run Run was also off, and it might be the same problem.

(05698) Tafoid (Administrator) 2010-02-10 21:47	That was believed to be an issue with the PSG. Positive contributions are always welcome if they are from original sources and MAME seems to be in dispute. Thanks.