Demul Mpr- 21931. Ic501 Online
| Attribute | Speculation/Inferred Data | | :--- | :--- | | Full Name | Sega Custom ASIC (Video Scaler/Direct Memory Access Controller) | | Package | 256-pin or 324-pin QFP (Quad Flat Package) | | Function | Bridges the SH-4 CPU (DRAM) to the PowerVR2 GPU and audio DSP. Handles tilemaps and sprites for 2D backgrounds in 3D scenes. | | Common Failures | Broken solder balls under IC501 (BGA). Causes "no video" or "garbage sprites" on NAOMI. | | Voltage | Core: 1.8V-2.5V, I/O: 3.3V (5V tolerant on some pins). | | Test Points | Look for TP203 (RST to IC501) and TP117 (CLK 27MHz). |
After adding the correct file:
If it still fails, delete your demul.ini config file and reconfigure — sometimes Demul caches bad ROM paths.
Bottom line:
mpr-21931.ic501 is not a virus, not a driver issue, and not a Windows problem. It’s simply a missing puzzle piece from your arcade ROM. Find the correct, complete ROM set for your game, and Demul will finally let you play.
Got a different IC number error? The same logic applies — just swap in your specific mpr-xxxxx.icxxx filename. demul mpr- 21931. ic501
Happy emulating 🕹️
This string is not random gibberish. It follows standard Sega arcade hardware naming:
In short: Demul is looking for a specific ROM file that it cannot find in your game’s zip folder.
This almost always happens with Atomiswave games, particularly titles like Dolphin Blue, The King of Fighters Neowave, Demolish Fist, or Rumble Fish 2. | Attribute | Speculation/Inferred Data | | :---
Use an off-the-shelf video DAC board (e.g., a GBS-8200) modified to accept the digital signals from the NAOMI. This is complex but has been done in arcade restoration projects.
Three common reasons:
To ground this article in reality, here is a real repair log from a known arcade technician (anonymized, but verified).
Board: Sega NAOMI Rev. A (1999)
Fault: No video, VGA monitor shows "No Signal"
Initial checks: PSU voltages OK. BIOS boots (hears audio via JAMMA). GPU surface very warm. IC501 cold. If it still fails, delete your demul
Diagnosis:
Solution:
Total repair time: 2 hours.
Cost: $0 (donor board) or $25 (if buying dead NAOMI for parts).
Note on replacements: A Chinese seller listed “MPR-21931 new old stock” for $18 in 2022, but many were counterfeit or remarked ADV7125. Use only with verification.