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Hardware Overview

The Casio BE-300 is built around a two-chip architecture: the NEC VR4131 system-on-chip provides the MIPS CPU and core peripherals, while the NEC VRC4173 companion chip handles video, touchscreen, CompactFlash, serial, and other I/O functions.

System Architecture

┌─────────────────────────────────────────────────────────┐
│                    NEC VR4131 SoC                        │
│  MIPS32 LE @ 166 MHz, 280 MIPS, PRId 0x00000C81        │
│                                                         │
│  On-chip: BCU, CMU, ICU, PMU, RTC, GIU, SIU, DSIU,    │
│           PCI, SDRAMU, SCU                              │
│  Peripheral I/O base: 0x0F000000                        │
└───────────┬─────────────────────────────────────────────┘
            │ Local bus / PCI
┌───────────┴─────────────────────────────────────────────┐
│               NEC VRC4173 Companion Chip                 │
│  Board ID 0x7100, I/O base: 0x0A000000                  │
│                                                         │
│  Peripherals: PIU (touchscreen), CF, SIU (serial),      │
│  GPIO, buzzer, CMU, video controller                    │
│  Framebuffer: 0x0A200000                                │
│  NAND controller: 0x0A000C00+                           │
└─────────────────────────────────────────────────────────┘

Key Components

Component Part Number Description
CPU/SoC NEC VR4131 MIPS32 little-endian, 166 MHz, 280 MIPS
Companion Chip NEC VRC4173 Peripheral controller, Board ID 0x7100
SDRAM Samsung K4S641633D (x2) 16 MB total (two 8 MB chips)
NAND Flash Samsung K9F2808U0B 16 MB, 1004 blocks, 32 pages/block, 512 bytes/page
LCD Controller EPSON L50753 Drives 320x240 32768-color STN panel
Boot ROM Masked ROM 16 KB at PA 0x1FC00000
Custom Chip Casio CAK2007 Proprietary Casio logic

Connectors

Connector Part Function
AC Jack Hosiden HEC3654 Power input
Headphone HSJ1636 Audio output
RS-232C TCX3110 Serial communication
CompactFlash -- Type I CF slot

Memory

The system has 16 MB of SDRAM mapped at physical address 0x00000000 through 0x00FFFFFF. The NAND flash is not memory-mapped; it is accessed through the VRC4173 NAND controller registers at 0x0A000C00. The 16 KB boot ROM is at 0x1FC00000 (accessible via kseg1 at 0xBFC00000).

See Memory Map for the complete physical address layout.

Board Photos

Photographs of the BE-300 mainboard, LCD assembly, and component identification are available on the Board Photos page.

Section Index