Project Frankenstein: Volume XX

Flash Status Registers & Error States

This volume provides the technical mapping of the Flash Memory Controller registers within the GCC-4241N (MN103S). While real-time monitoring of a physical burn is restricted by the hardware's halt state during RAM-stub execution, understanding these registers is vital for the RAM Stub logic to verify sector erasures and program success before signaling a safe completion [cite: User Summary, Volume XIX: Flash Programming Algorithm].

1. Flash Controller Register Map (VMA)

The MN103S interfaces with the on-board flash memory through dedicated peripheral registers. These are mapped in the high I/O space [cite: User Summary].

Register Name Address (VMA) Description
FLASH_STATUS 0x9000F000 Read-only register reporting the state of the internal flash state machine.
FLASH_CMD 0x9000F008 Command register used to issue Erase, Program, and Reset sequences.
FLASH_ADDR 0x9000F00C Sets the internal address counter for physical block operations.

2. Status Register Bit-Field Analysis

The FLASH_STATUS register (0x9000F000) provides granular feedback on the physical state of the flash cells [cite: User Summary].

Bit Mnemonic Description / Hybrid Relevance
$7$ RY/BY# Ready/Busy: 1 = Ready (Operation Complete); 0 = Busy [cite: Volume XIX: Flash Programming Algorithm].
$5$ EERR Erase Error: Set to 1 if a sector erase operation fails. Indicates physical cell degradation.
$4$ PERR Program Error: Set to 1 if the current data write fails to verify.
$1$ VPPERR Vpp Error: Set to 1 if the programming voltage (Vpp) is insufficient for a write.

3. The RAM Stub Verification Loop

Theory: Safe Exit Logic

Because the Host cannot monitor the burn, the RAM Stub must perform internal validation. If a write fails, the stub must purposefully enter an infinite "Panic" loop (LED Flash) rather than signaling success to prevent booting a corrupted kernel [cite: Volume XIX: Flash Programming Algorithm].

MN103S Assembly: Verification Check

; Check Flash Status for Program Error
; Location: Inside the RAM Stub burn loop
check_flash_status:
    mov     0x9000F000, a0  ; Point to FLASH_STATUS
    movbu   (a0), d0        ; Load current status
    
    ; Test Bit 7 (Ready)
    btst    7, d0           
    beq     check_flash_status ; Wait if Busy (0)
    
    ; Test Bit 4 (Program Error)
    btst    4, d0           
    bne     flash_panic_loop ; If PERR=1, jump to failure handler
    
    ret                     ; Success, continue to next chunk

4. Flash Error Diagnostics

If a drive is bricked, the developer can use Method B or Peek (if the bootloader is intact) to inspect 0x9000F000 to determine if the hardware physically failed during the last burn [cite: Project_Frankenstein_Vol_VIII_Peek_Poke.html].

PROJECT FRANKENSTEIN // VOLUME XX // FLASH STATUS MAPPING // 2026-05-01