Viewing Issue Advanced Details
ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
07573 Sound Major Always Feb 23, 2020, 15:57 Jun 1, 2020, 11:58
Tester mcp View Status Public Platform MAME (Official Binary)
Assigned To Resolution Open OS Windows 10 (64-bit)
Status [?] Confirmed Driver
Version N/A Fixed in Version Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary 07573: netwars: Net Wars Sound incorrect: MAME version plays sound much slower than ARCADE version
Description Net Wars sound is incorrect compared to the Arcade version of the game.
My arcade version is an original with the Esco Trading License shown in start screen.

First occurence:
"Insert Coin" plays a short sound effect in the Arcade version. (see/hear my video)
In te MAME version there is the same sound effect but much slower!

Second occurence:
When the game starts and the initial screen shows "Player one start / Good Luck" the spaceship appears from right, goes to left, comes from left and goes to right side .... while this is done a complete "melody" is played in the Arcade version.
Compared to the MAME version there is only played the inital sound-effect and this lasts for about the whole time the space ship travels over the screen twice until the game itself starts.
Then - in the MAME version - is the sound played while gaming but much slower. Everything is much slower in MAME compared to the arcade version.
(see/hear my video)
Steps To Reproduce Download video here:
Additional Information
Github Commit
Flags Verified with Original
Regression Version
Affected Sets / Systems netwars
Attached Files
There are no relationship linked to this issue.
User avatar
Feb 26, 2020, 19:25
can you provide more information about this game ? PCB photo, XTALs labels, and in perfect case - measure sound CPU NMI pin clock (which define sounds playback speed) and frame rate.
User avatar
Feb 27, 2020, 10:07
XTALs are the same as with Espial, 18.432 MHz (mid-board) and 12 MHz (bottom board).

CPU CLK: both 2.99997 MHz (~ 3 MHz )

NMI Clk: (I compared my Espial with Net Wars boards)
Espial NMI (pin 17) shows 236.000 Hz / Net Wars shows 1.638 KHz ( ~ 1.640 Khz )

Can send photos later if still needed. (just let me know)
I have visually insepected all my Espial and Net Wars PCBs, and the only difference is on the bottom board: one solder-bridge which handles the video ram.
User avatar
Feb 28, 2020, 13:14
thank you very much, with sound CPU NMI generated @1640Hz it sounds close to video recorded from PCB. but still not perfect match, perhaps caused by not accurate some other clocks.
can you please measure main CPU NMI and IRQ clocks ?

speaking in general, I'd guess this sound PCB have programmable timer, which generate sound CPU NMI, and it's frequency/divider probably controlled via AY-8910 GPIO PortA, Espial set it to FEh, while Net Wars set it to F8h. this may explain why 2 these PCBs have different NMI clock.

high likely Dog Fight issue have the same cause
User avatar
Feb 29, 2020, 10:34
edited on: Feb 29, 2020, 10:36
main CPU:
  NMI Clk: 59.000 Hz
  INT Clk: 59.000 Hz

Sound CPU (again measured):
  NMI Clk: 1.638 - 1.640 KHz (jumping with focus on first)
  after INSERT COIN the NMI Clk changes to: 1.651 - 1.652 KHz (this is as long as "PUSH ONLY ONE PLAYER ..." is visible on screen)
      (note: 1.652 is exactly 236 x 7, no need to tell you)
  after Push on PLAYER 1 button (while initial sound tune) the NMI Clk changes to: 670 Hz, 651 Hz, 795 Hz, 931 Hz, ...
  while gameplay (player's ship on raster) the NMI Clk changes to: 1.151 - 1.155 KHz (even 1.156 KHz seen)

I made another Video (this time from the oscilloscope showing NMI clock) including game sound, so you can see perfectly how this changes:

(side note: I have a Dog Fight as well if something is needed let me know)
User avatar
Jun 1, 2020, 11:58
MetalliC ... just wanted to let you know:
I found an Espial board which plays music much faster than all other Espial I have.
I will investigate if there is something different with hardware...I suspect not, it might be a fault in an ic but want to go sure.
Maybe this is only coincidence but who knows.