Bios: Casper-uma-cr-hpb Mv-mb-v1

"Casper" is an internal code name used by HP/Google for certain Chromebook or low-power embedded platforms. "UMA" = Unified Memory Architecture (integrated GPU). "CR" = Customer Reference board. "HPB" = High Performance Battery or HP Board. "mv-mb-v1" = Motherboard version 1. 1. Core System Configuration | Feature | Description | |---------|-------------| | CPU Support | Intel Celeron/Pentium Silver (Gemini Lake / Gemini Lake-R) or similar low-power SoC (e.g., N4000, N4120, J4125) – soldered | | UMA Graphics | Intel UHD Graphics 600; shared system memory (configurable from 128MB to 512MB) | | Memory | LPDDR4 / DDR4 soldered or SO-DIMM (depending on board variant); no ECC support | | Storage | eMMC (default boot device), optional SATA port (mSATA or 2.5" disabled in some SKUs), microSD card reader | | Boot Modes | UEFI only (no legacy CSM) – ChromeOS/Windows 10/11 64-bit | 2. Security & Firmware Features | Feature | Description | |---------|-------------| | Secure Boot | UEFI Secure Boot with custom HP/Google keys; can be disabled for developer mode | | TPM | TPM 2.0 (discrete or firmware-based, depending on build) | | Write Protection (WP) | Hardware write-protect screw/pin for BIOS flash – essential for ChromeOS recovery | | Verified Boot | (If ChromeOS) – ChromeOS-style verified boot with root of trust | | BIOS Recovery | Emergency recovery via USB (specific key combo: ESC + Refresh + Power) | | Absolute Computrace | Optional (if licensed); persistent tracking module | 3. Power & Thermal Management | Feature | Description | |---------|-------------| | ACPI States | S0 (active), S3 (suspend to RAM), S4 (hibernate), S5 (soft off) | | Thermal Throttling | Passive (CPU freq reduction) @ 70°C; active (fan control) @ 80°C | | Fan Control | 1x 4-pin PWM header (if chassis includes fan) – otherwise fanless design | | Battery Management | Smart Battery System (SBS) support for Li-ion packs; configurable charge thresholds (90% for longevity) | | Deep Sleep | Enabled by default; reduces power to PCIe and USB during S3 | 4. Boot & Peripheral Control | Feature | Description | |---------|-------------| | Boot Order | UEFI boot entries: USB HDD → eMMC → SATA → Network (PXE) | | Fast Boot | Skips memory retraining and some POST checks – reduces boot time by ~3 sec | | PXE Boot | UEFI IPv4/IPv6 network boot (requires signed UEFI driver) | | USB Wake | Wake from S3 via USB keyboard/mouse (configurable) | | Wake on LAN | Magic packet wake (requires AC power connected) | | Serial Console | UART1 (3.3V, 115200 8N1) for debug – enabled in engineering builds only | 5. Integrated Peripherals Configuration | Device | Options in BIOS | |--------|----------------| | Audio | Realtek ALC256/274 – enable/disable HDMI audio, internal speaker amp | | WiFi/BT | M.2 2230 (PCIe+USB) – enable/disable, MAC pass-through control | | Camera | MIPI-CSI (internal) – enable/disable | | SD Card Reader | enable/disable, set boot priority | | USB Ports | Individual port enable/disable (2x USB 3.0 + 1x USB 2.0 typical) | | HDMI | Enable/disable, HDCP 1.4/2.2 control | | eDP/LVDS | Panel backlight brightness, PWM frequency (200Hz – 10kHz) | 6. Hidden / Advanced Menus (Unlocked only) These are not visible in end-user BIOS; accessible via Ctrl+A or special debug BIOS.

| Option | Description | |--------|-------------| | | Adjust UMA buffer size (128/256/512MB), enable "slow training" for stability | | PCIe ASPM | Active State Power Management – L0s, L1 substates | | CPU C-States | C1E, C6, C10 – disabling can improve latency but increases heat | | S5 RTC Wake | Scheduled power-on from RTC (hour/day/minute) | | BIOS Lock | Disable SMM BIOS write protection (risky) | | ME Disable | Disable Intel Management Engine (only on certain early engineering samples) | 7. Typical User-Accessible BIOS Menu Tree Main ├─ System Information (BIOS version, CPU, RAM, serial) ├─ Set System Date/Time └─ Access Level (Administrator/User) Security ├─ Set Administrator Password ├─ Set User Password ├─ Secure Boot Configuration │ ├─ Secure Boot Enable/Disable │ ├─ Reset to Setup Mode │ └─ Key Management ├─ TPM Configuration (Clear, Enable) └─ BIOS Write Protection (if jumper present) casper-uma-cr-hpb mv-mb-v1 bios

Boot ├─ Boot Order (touch/drag to reorder) ├─ UEFI Boot Sources ├─ Fast Boot (Enable/Disable) └─ Network Boot (Enable/Disable) "Casper" is an internal code name used by

Power ├─ Wake on LAN (Off / LAN / WLAN) ├─ USB Wake Support ├─ Battery Charge Threshold (80% / 50% / 100%) └─ Deep Sleep (Enable/Disable) "HPB" = High Performance Battery or HP Board

(as of 2024): F.12 or Google_Casper.11200.238.0 (depending on OS) 10. Common Diagnostics / Key Combinations | Keys (POST) | Function | |-------------|----------| | F2 or ESC | Enter BIOS Setup | | F9 | Boot Menu (one-time) | | F10 | Save & Exit (from BIOS) | | ESC + Refresh + Power | ChromeOS recovery mode (if ChromeOS build) | | Ctrl + L (dev screen) | Legacy boot (non-existent – shows error) | | Ctrl + D (dev screen) | Developer mode boot |