Firmware Architecture Flowchart

Firmware Architecture Flowchart

This page documents the complete execution flow of the KN5000 firmware, from power-on through steady-state operation. The firmware runs on a TMP94C241F (TLCS-900/H2) CPU at 16 MHz with a cooperative multitasking scheduler.

Power-On Boot Sequence

flowchart TD
    RESET["RESET Vector
(0xE00000)"] --> HW_INIT["Hardware Init
IO ports, stack, RAM clear"]
    HW_INIT --> SELF_TEST["Self Test
ROM checksum, RAM test"]
    SELF_TEST --> FW_VER{"Firmware
version?"}
    FW_VER -->|"v0xFF (boot ROM)"| SHOW_WAIT["Display
'Please Wait !!'"]
    FW_VER -->|"Normal"| POST_TEST["Post Self Test"]
    SHOW_WAIT --> POST_TEST
    POST_TEST --> TASK_INIT["TaskSched_Init
Initialize cooperative scheduler"]
    TASK_INIT --> PERIPH["Init Peripherals
GPIO, region code"]
    PERIPH --> FLASH["Flash_InitAllBanks
Initialize flash memory"]
    FLASH --> HDAE{"HD-AE5000
present?"}
    HDAE -->|Yes| PPI_INIT["HDAE5000 PPI Init
Parallel port interface"]
    HDAE -->|No| SEQ_INIT
    PPI_INIT --> SEQ_INIT["Seq_FullInit
Sequencer initialization"]
    SEQ_INIT --> CPANEL["CPanel_ScanButtons
Read power-on key combo"]
    CPANEL --> FLASH_UPD{"Key combo =
flash update?"}
    FLASH_UPD -->|Yes| FW_UPDATE["FLASH_MEM_UPDATE
Firmware update from floppy"]
    FLASH_UPD -->|No| MAIN_BOOT
    FW_UPDATE --> HALT["Boot_MainSequence_Trampoline
(infinite loop — reboot required)"]

    subgraph MAIN_BOOT ["Main Boot Path"]
        FACTORY{"Factory reset
requested?"}
        FACTORY -->|Yes| RESET_DRAM["Clear all DRAM + SRAM"]
        FACTORY -->|No| SUBCPU_INIT
        RESET_DRAM --> SUBCPU_INIT["SubCPU_Init_DMA_Channels"]
        SUBCPU_INIT --> PAYLOAD["SubCPU_Send_Payload
Transfer 192KB firmware"]
        PAYLOAD --> VERIFY["SubCPU_Payload_Verify
Checksum validation"]
        VERIFY --> SCREEN0["ScreenGroup_Dispatch(0)
Initial boot screen"]
        SCREEN0 --> CHECK_ERR{"Payload
transfer OK?"}
        CHECK_ERR -->|Error| ERR_SCREEN["ScreenGroup_Dispatch(2)
'ERROR in CPU data'"]
        CHECK_ERR -->|OK| BOOT_SCREEN["Boot_DisplayScreen
ScreenGroup_Dispatch(1)"]
    end

    BOOT_SCREEN --> MAIN_LOOP

Main Event Loop

After boot, the firmware enters a cooperative multitasking loop driven by a task scheduler and event dispatch system.

flowchart TD
    BOOT["Boot_DisplayScreen"] --> INIT_SUBSYS["Initialize All Subsystems"]

    subgraph INIT_SUBSYS ["Subsystem Initialization"]
        INIT_NAKA["InitializeNaka
Register 478 UI widget objects"]
        INIT_HAMA["InitializeHama
Register file I/O titles"]
        INIT_AUDIO["AudioInit
Tone gen, DSP, voice allocation"]
        INIT_MIDI["MIDI Init
Serial port, routing tables"]
        INIT_SEQ["Sequencer Init
Ring buffers, part state"]
    end

    INIT_SUBSYS --> MAIN_LOOP

    subgraph MAIN_LOOP ["Main Event Loop (cooperative multitasking)"]
        SCHED["TaskSched_Dispatch
Run next ready task"]
        SCHED --> EVT_CHECK{"Events
pending?"}
        EVT_CHECK -->|Yes| EVT_DISPATCH["Event Dispatch
Route to registered handler"]
        EVT_CHECK -->|No| TIMER_CHECK{"Timer
expired?"}
        EVT_DISPATCH --> SCHED
        TIMER_CHECK -->|Yes| TIMER_HANDLER["Timer Handler
Sequencer tick, UI refresh"]
        TIMER_CHECK -->|No| SCHED
        TIMER_HANDLER --> SCHED
    end

Interrupt Service Routines

The firmware uses hardware interrupts for real-time operations. ISRs feed data into ring buffers consumed by the main loop.

flowchart LR
    subgraph ISR ["Hardware Interrupts"]
        DMA_ISR["E1 DMA ISR
Inter-CPU data transfer"]
        TIMER_ISR["Timer ISR
System tick (1ms)"]
        SERIAL_ISR["Serial ISR
MIDI RX/TX, Control Panel"]
    end

    subgraph BUFFERS ["Ring Buffers"]
        NOTE_BUF["NoteEvent Buffer
(0x0203D5)"]
        SOUND_BUF["SoundEdit Buffer"]
        VOICE_BUF["VoiceMap Buffer
(0x0201C1)"]
        DSP_BUF["DspSysEx Buffer
(0x01FCA3)"]
        MIDI_BUF["MIDI Out Buffer
(0x01F785)"]
    end

    DMA_ISR --> NOTE_BUF
    DMA_ISR --> SOUND_BUF
    DMA_ISR --> VOICE_BUF
    DMA_ISR --> DSP_BUF
    SERIAL_ISR --> MIDI_BUF

Subsystem Architecture

flowchart TD
    subgraph UI_LAYER ["UI Layer"]
        NAKA["NAKA Widget Framework
478 widget objects, 9 type codes"]
        SCREEN["Screen Manager
Screen groups, mode dispatch"]
        DRAW["Drawing Primitives
Lines, boxes, text, bitmaps"]
        VGA["VGA Controller
320x240 8bpp LCD"]
    end

    subgraph AUDIO_LAYER ["Audio Layer"]
        TONEGEN["Tone Generator (IC303)
64 voices, PCM wavetable"]
        DSP["DSP Effects
IC310 (serial) + IC311 (parallel)"]
        VOICE["Voice Allocator
Note-on/off, velocity, pan"]
        SNDPARAM["Sound Parameters
Preset lookup, category maps"]
    end

    subgraph SEQ_LAYER ["Sequencer Layer"]
        SEQ["Sequencer Engine
16-track, ring buffer playback"]
        ACCOMP["Accompaniment Engine
Rhythm, bass, chord patterns"]
        SMF["SMF Player
Standard MIDI File playback"]
        STYLE["Style System
SSF data, variation select"]
    end

    subgraph IO_LAYER ["I/O Layer"]
        CPANEL["Control Panel
Serial protocol, 150 buttons, 119 LEDs"]
        MIDI["MIDI
31250 baud UART, SysEx, CC routing"]
        FDC["Floppy Disk
UPD72067 controller"]
        IDE["IDE/ATA
HD-AE5000 hard disk"]
        FLASH["Flash Memory
User settings, custom data"]
    end

    subgraph CPU_LAYER ["Inter-CPU Communication"]
        MAIN["Main CPU
TMP94C241F @ 16MHz"]
        SUB["Sub CPU
TMP94C241F (audio engine)"]
        LATCH["Latch @ 0x140000
Command/response protocol"]
    end

    UI_LAYER --> AUDIO_LAYER
    UI_LAYER --> SEQ_LAYER
    SEQ_LAYER --> AUDIO_LAYER
    AUDIO_LAYER --> CPU_LAYER
    IO_LAYER --> UI_LAYER
    IO_LAYER --> SEQ_LAYER
    MAIN <-->|"E1/E2/E3 commands"| LATCH
    LATCH <-->|"DMA bulk transfer"| SUB
    SUB --> TONEGEN
    SUB --> DSP

NAKA Widget Event Flow

The UI framework uses a hierarchical event dispatch system. Events flow from hardware through the control panel to NAKA widget handlers.

flowchart TD
    BUTTON["Physical Button Press"] --> CPANEL_ISR["Control Panel ISR
Serial packet decode"]
    CPANEL_ISR --> EVT_GEN["Generate Event ID
(e.g., 0x01C00008 = DISK MENU)"]
    EVT_GEN --> VIEWABLE["ViewableProc
(0xFA5995)"]
    VIEWABLE --> TYPE_CLASS["SeMenu_SetObjectFlags
Classify by widget type"]
    TYPE_CLASS --> HANDLER_TABLE["handler_table lookup
(DRAM dispatch table)"]
    HANDLER_TABLE --> INHERITED["InheritedProc
Walk parent chain"]

    subgraph WIDGETS ["Widget Handlers"]
        CONTAINER["Container Handler
Screen root, layout"]
        MENU_ITEM["Menu Item Handler
Selection, navigation"]
        SLIDER["Slider Handler
Value adjustment"]
        DISPATCH["Dispatch Handler
Proc function call"]
    end

    INHERITED --> CONTAINER
    INHERITED --> MENU_ITEM
    INHERITED --> SLIDER
    INHERITED --> DISPATCH
    DISPATCH --> PROC["Proc Function
(e.g., IvDrawbarProc)"]
    PROC --> ACTION["UI Action
Sound change, screen transition"]

Memory Map Overview

flowchart LR
    subgraph ADDR_SPACE ["24-bit Address Space"]
        INT_RAM["0x000000-0x000FFF
Internal RAM (4KB)
CPU registers, stack"]
        IO["0x001000-0x0FFFFF
I/O & Peripherals
Timers, serial, DMA"]
        TONE["0x100000-0x15FFFF
Tone Gen Hardware
64 voices × 32 regs"]
        VRAM["0x1A0000-0x1DFFFF
VRAM (256KB)
320×240 8bpp LCD"]
        DRAM["0x200000-0x27FFFF
Extension DRAM (512KB)
Sequencer, NAKA state"]
        HDAE["0x280000-0x2FFFFF
HDAE5000 ROM (512KB)
Hard disk expansion"]
        CUSTOM["0x300000-0x3FFFFF
Custom Data Flash
User settings"]
        TABLE["0x800000-0x9FFFFF
Table Data ROM (2MB)
Styles, rhythms, demos"]
        PROG["0xE00000-0xFFFFFF
Program ROM (2MB)
Main firmware"]
    end

Source File Organization

flowchart TD
    MAIN["kn5000_v10_program.s
(3,400 lines — entry point)"]

    subgraph BOOT_FILES ["Boot & System"]
        BOOT_HW["shared/boot_hw_init.s"]
        SYS_HAND["boot/system_handlers.s"]
        FACTORY["factory_test/test_*.s"]
    end

    subgraph UI_FILES ["UI Framework (19 .s + 27 .c)"]
        WIDGET_DEFS["ui/ui_widget_defs.s (19K)"]
        DRAW_PRIM["ui/drawing_primitives.s"]
        CPANEL_RT["ui/cpanel_routines.s"]
        NAKA_C["ui_widgets/*.c (26 files)
Typed C struct widget data"]
    end

    subgraph AUDIO_FILES ["Audio (31 files)"]
        ACE["audio/audio_control_engine.s (8K)"]
        NVM["audio/note_voice_mapping.s (26K)"]
        SEMENU["audio/semenu_routines.s"]
        DSP_CFG["audio/dsp_config_sysex.s"]
        SND_DATA["audio/sound_data_*.s (7 files)"]
    end

    subgraph SEQ_FILES ["Sequencer (15 files)"]
        ACC_ENG["sequencer/accompaniment_engine.s (33K)"]
        SEQ_ENG["sequencer/sequencer_engine.s (32K)"]
        SMF_PLAY["sequencer/smf_playback.s"]
    end

    subgraph MIDI_FILES ["MIDI (9 files)"]
        MIDI_SER["midi/midi_serial_routines.s"]
        MIDI_DISP["midi/midi_dispatch_handlers.s"]
        SYSEX["midi/sysex_routines.s"]
    end

    subgraph STORAGE_FILES ["Storage (2 files)"]
        FDC_RT["storage/fdc_routines.s"]
        FLASH_RT["storage/flash_floppy_handlers.s"]
    end

    MAIN --> BOOT_FILES
    MAIN --> UI_FILES
    MAIN --> AUDIO_FILES
    MAIN --> SEQ_FILES
    MAIN --> MIDI_FILES
    MAIN --> STORAGE_FILES

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Disassembly Statistics

Metric	Value
Total native instructions	279,441 (0 code .byte remaining)
Assembly source files	154 (.s) + 70 (.c)
ROM byte match	100% on all 6 ROMs
Labeled symbols	37,276 (0 opaque LABEL_XXXXXX)
NAKA widget C structs	26 files with typed fields

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Auto-generated from KN5000 ROM disassembly analysis. Last updated: March 2026.