Skip to content

CHANGELOG.md

Latest commit

 

History

History
1203 lines (974 loc) · 50.1 KB

CHANGELOG.md

File metadata and controls

1203 lines (974 loc) · 50.1 KB

Changelog

All notable changes to UnoDOS will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[3.19.0] - 2026-02-16

Added (Builds 202-212) - FAT12 Write, GUI Toolkit, Settings Persistence

  • FAT12 Write Support (Build 202)

    • fs_create_stub (API 45) — Create new file on FAT12 floppy
    • fs_write_stub (API 46) — Write data to open file
    • fs_delete_stub (API 47) — Delete file from FAT12 floppy
    • fs_write_sector_stub (API 44) — Write raw sector to disk
    • Full FAT12 cluster chain allocation for multi-cluster files

  • Boot Floppy Creator (MkBoot) (Builds 202-204)

    • New app: creates bootable UnoDOS floppy from running system
    • Pre-reads apps to RAM, prompts for disk swap, writes boot+kernel+apps
    • Floppy-to-floppy copy workflow for users without build tools

  • GUI Toolkit Foundation (Build 205)

    • Multi-font system: 4x6 small, 8x8 medium, 8x14 large fonts
    • gfx_set_font (API 48), gfx_get_font_metrics (API 49)
    • Word-wrap text drawing: gfx_draw_string_wrap (API 50)
    • Widget APIs: widget_draw_button (51), widget_draw_radio (52), widget_hit_test (53)
    • Clip rectangle system for constraining drawing operations

  • Settings App (Builds 206-210)

    • Font selection (small/medium/large) with live preview
    • Color theme: text color, desktop background, window color (4 CGA colors)
    • Color swatch picker with radio buttons for font selection
    • Apply/OK/Defaults buttons
    • Settings persist to SETTINGS.CFG on boot floppy via FAT12 write APIs
    • Kernel loads settings at boot before launching apps

  • Color Theme System (Builds 208-209)

    • theme_set_colors (API 54), theme_get_colors (API 55)
    • draw_bg_color for text background rendering
    • Desktop background color, window frame color, text color all configurable

Fixed (Builds 202-212)

  • Disappearing Windows (Build 211): Drawing APIs 0 (pixel), 1 (rect), 2 (filled rect) didn't hide mouse cursor during drawing. IRQ12 could XOR the cursor over window frame pixels between API calls, progressively corrupting borders. Fixed by adding cursor_hide/cursor_locked to all drawing APIs.
  • MkBoot Window Redraw (Build 211): MkBoot defined API_WIN_DRAW equ 30 but the correct value is 22. API 30 is mouse_is_enabled, so the window redraw call was silently doing nothing.
  • draw_bg_color Pollution (Build 211): draw_desktop_region set draw_bg_color to desktop color but never restored it, leaking into subsequent window drawing operations.
  • fs_open_stub Mount Handle (Build 210): Compared full 16-bit BX for mount handle routing, but callers set only BL. Dirty BH caused silent open failures. Fixed to compare BL only.
  • fs_readdir_stub Mount Handle (Build 209): Same BX vs BL routing bug as fs_open_stub.
  • Button Text Overflow (Build 210): widget_draw_button didn't clip label text to button bounds. Fixed by setting clip rectangle before drawing label.
  • Mouse Click Events (Build 207): event_get_stub wasn't setting CF flag correctly for mouse events, causing click handlers to miss events.

Changed (Builds 202-212)

  • API table expanded from 44 to 56 function slots (APIs 44-55)
  • CGA pixel plotting functions refactored: shared cga_pixel_calc helper saves ~100 bytes (Build 212)
  • FAT12 stack cleanup comments updated from stale line numbers to descriptive labels (Build 212)
  • File handle validation uses FILE_MAX_HANDLES constant instead of magic number 16 (Build 212)
  • Coordinate translation in INT 0x80 handler now covers APIs 0-6 and 50-52 (widget APIs)

[3.18.0] - 2026-02-16

Added (Builds 194-201) - Splash Screen, Multitasking Fixes, Refresh Icon

  • Splash Screen with Logo (Builds 196-201)

    • "U" logo drawn with white filled rectangles during boot
    • "UnoDOS 3" title and "Loading..." text displayed
    • Progress bar fills as apps are discovered from disk
    • Replaces blank/debug screen during launcher initialization
    • Fast CGA memory clear via REP STOSW (Build 200)

  • Floppy Refresh Icon (Build 195)

    • Manual disk rescan icon appears as last desktop icon on floppy boot
    • 3.5" floppy disk shape (16x16 2bpp CGA bitmap)
    • Replaces automatic INT 13h AH=16h polling (caused constant floppy seeking)
    • Only shown when booted from floppy

  • Launch Error Feedback (Build 195)

    • "Insert app disk" message for mount/file errors (codes 2, 3)
    • Error message auto-clears after ~2 seconds with desktop redraw

Fixed (Builds 194-201)

  • File Browser HD Support (Build 194): Browser now queries boot drive and saves mount handle, fixing blank listing on HD/CF/USB boot
  • Floppy Seeking Noise (Build 195): Removed automatic floppy swap polling (INT 13h AH=16h) that caused audible seeking on IBM PS/2 L40
  • Music App Single Tone (Build 197): App played one constant note instead of Fur Elise melody. Root cause: app_yield_stub didn't preserve general-purpose registers across context switches, so CX (note duration) was clobbered by the launcher. Fixed with pusha/popa.
  • App Launch Crash (Build 198): Adding pusha/popa to yield broke new task startup — popa consumed return addresses instead of register values. Fixed by adding dummy pusha frame (8 zero words) to initial task stack built by app_start_stub.
  • Initial Context Switch Loop (Build 201): auto_load_launcher did bare ret without popa, popping 0 from the dummy pusha frame instead of int80_return_point. This jumped to kernel entry (0x0000) in an infinite loop: boot → load launcher → ret to kernel → repeat. Fixed by adding popa before ret in both auto_load_launcher and app_exit_common.

Changed

  • Bootloader version updated from v0.2 to v3.18
  • All boot diagnostic code removed (keypress wait, BIOS teletype, CGA white boxes, PRE/POST markers)
  • Splash screen text uses transparent background (Build 199)
  • Desktop/splash screen clear uses direct CGA REP STOSW (Build 200)

Removed

  • Kernel boot keypress wait
  • Kernel BIOS teletype diagnostic output
  • Kernel "PRE"/"POST" CGA diagnostic strings
  • Launcher CGA diagnostic white boxes (marks 1-6)

[3.17.0] - 2026-02-15

Added (Builds 162-193) - Universal PS/2 Mouse via BIOS Services

  • BIOS PS/2 Mouse Driver (Build 187+)

    • Uses BIOS INT 15h/C2xx services instead of direct KBC port I/O
    • INT 15h/C205 (init), C207 (set callback), C200 (enable)
    • Works with USB mice via BIOS legacy emulation (SMI-based)
    • FAR CALL callback handler (mouse_bios_callback) processes packets from BIOS
    • Falls back to direct KBC method if BIOS services unavailable

  • Robust KBC Mouse Init (Build 185)

    • KBC output buffer flush (16-byte drain loop) before init
    • Keyboard interface disabled (0xAD) during mouse setup
    • Long timeout for ACK wait (~1 second via BIOS timer tick)
    • Mouse reset retried up to 3 times
    • Keyboard re-enabled (0xAE) on both success and failure

  • Boot Diagnostic (Build 184+)

    • Mouse init result displayed at boot: B=BIOS, K=KBC, R/S/E=failure
    • Keypress wait after diagnostic for hardware verification

Fixed (Builds 162-193)

  • USB Legacy Emulation Conflict (Build 187): BIOS SMI handler was overriding direct KBC port writes, re-masking IRQ12 and disabling aux clock. Solved by switching to BIOS INT 15h/C2 services which work with the SMI handler.
  • BIOS Callback AH Corruption (Build 188): mov ah, bh in X sign-extend overwrote the status byte stored in AH, breaking Y sign extension.
  • Callback Byte Order (Build 192): Discovered via QEMU raw stack dump that BIOS pushes status,X,Y,0 before CALL FAR, making [BP+12]=status, [BP+10]=X, [BP+8]=Y, [BP+6]=padding. All previous convention assumptions were wrong.
  • IRQ2 cascade unmask added for IRQ12 propagation (Build 186)
  • Removed fragile auto-detection of callback byte conventions (Build 192)

Changed

  • Mouse driver architecture: BIOS services primary, direct KBC fallback
  • Kernel alignment pad bumped (0x11A0 → 0x13A0) for new mouse init code

[3.16.0] - 2026-02-14

Added (Build 161) - Hard Drive Boot Support

  • Hard Drive Boot Verified (Build 161)

    • Full MBR → VBR → Stage2_hd → Kernel boot chain tested
    • FAT16 filesystem on 64MB partition with all apps
    • Boots from hard drives, CF cards, and USB flash drives (via BIOS emulation)

  • Boot Drive Query API (Build 161)

    • New API 43: get_boot_drive — returns boot drive number in AL
    • Enables apps to detect floppy (0x00) vs hard drive (0x80) boot

Fixed (Build 161)

  • Launcher now queries boot drive from kernel instead of hardcoding floppy
  • Launcher uses correct mount handle for FAT12/FAT16 routing
  • read_bin_header uses dynamic mount handle (was hardcoded FAT12)
  • Floppy swap detection skipped when booted from hard drive
  • fat16_read 32-bit arithmetic: sector calculation no longer truncates to 16 bits
  • MUSIC.BIN added to HD image (was missing from create_hd_image.py)

Changed

  • API table expanded from 43 to 44 functions (get_boot_drive)
  • Launcher detects boot media type automatically

[3.15.0] - 2026-02-14

Added (Builds 151-159) - Window Manager, Sound, Close Button

  • Window Close Button (Build 152)

    • button drawn at right side of title bar
    • Click to terminate app and destroy window
    • Speaker silenced on app exit (prevents stuck tones)
    • Works for both current and background tasks

  • PC Speaker Sound (Build 152)

    • New APIs: speaker_tone (41), speaker_off (42)
    • PIT Channel 2 programming for frequency generation
    • Automatic speaker silence on task termination

  • Music Player App (Build 152)

    • MUSIC.BIN - Beethoven's Fur Elise opening theme
    • Sequential note playback via PC speaker
    • BIOS tick counter timing (~18.2 Hz)
    • Musical note icon in app header

  • Outline Drag (Build 156)

    • XOR rectangle outline during window drag (Windows 3.1 style)
    • Window moves once on mouse release, single clean repaint
    • Replaced pixel save/restore drag (~235 lines removed)

  • Z-Order Window Management (Builds 155-159)

    • Background windows blocked from drawing over foreground
    • Topmost window bounds cache for O(1) clipping
    • Active/inactive title bar visual distinction
    • Active: filled white title bar with black text
    • Inactive: black title bar with white text outline
    • Automatic title bar style update on focus change

Fixed (Builds 151-159)

  • Build 153: Floppy read retry logic for reliable loading on real hardware
  • Build 154: App load error code diagnostic in launcher
  • Build 155: Background windows losing content due to overzealous z-order clipping
  • Build 157: Post-drag z-order — desktop icons and background frames showing through moved window
  • Build 158: Per-draw-call z-order clipping (point-inside-topmost check)
  • Build 159: Simplified to full background draw blocking (fixes multi-pixel bleed-through)

Changed

  • API table expanded from 41 to 43 functions (speaker_tone, speaker_off)
  • Window drag: outline-based instead of content save/restore
  • Draw API calls from background windows silently dropped (apps repaint on focus)
  • Title bar style differentiates active vs inactive windows

[3.14.0] - 2026-02-13

Added (Builds 144-150) - Desktop Icons, Multi-App, Multitasking

  • Desktop Icon System (Build 144)

    • 4x2 icon grid with 16x16 2bpp CGA icon bitmaps on desktop
    • BIN file icon headers (80 bytes: JMP + "UI" magic + 12B name + 64B bitmap)
    • Automatic icon detection from BIN headers at boot
    • Default icon for legacy apps without headers
    • Mouse double-click to launch (~0.5s threshold)
    • Keyboard navigation (arrows/WASD + Enter)
    • New APIs: desktop_set_icon (37), desktop_clear_icons (38), gfx_draw_icon (39), fs_read_header (40)

  • Cooperative Multitasking (Build 144)

    • Round-robin cooperative scheduler (app_yield, app_start)
    • Per-task draw_context save/restore
    • Per-task event filtering (KEY_PRESS to focused, WIN_REDRAW to owner)

  • Multi-App Concurrent Execution (Build 149)

    • Dynamic segment pool: 6 user segments (0x3000-0x8000)
    • alloc_segment / free_segment kernel helpers
    • Up to 6 concurrent user apps + launcher
    • Scratch buffer moved from 0x5000 to 0x9000

  • Window Title Bar Text (Build 150)

    • Fixed gfx_draw_string_inverted reading from wrong segment for titles

Fixed (Builds 145-148)

  • Build 145: Window drag content flicker
  • Build 146: Desktop z-order, floppy detection, version display
  • Build 147: Mouse test app, icon repaint, icon deselect
  • Build 148: Double-ESC exit bug (event queue), hello window sizing

Changed

  • API table expanded from 34 to 41 functions
  • Memory: 6 dynamic user segments (0x3000-0x8000) replace single 0x3000
  • Scratch buffer relocated from 0x5000 to 0x9000
  • Launcher rewritten as fullscreen desktop with icon grid

[3.13.0] - 2026-02-11

Fixed (Build 135) - Text Width Measurement

  • gfx_text_width returned wrong values - Was reporting 8px per character but draw_char advances 12px (8px glyph + 4px gap). Fixed to return 12px per character, matching actual rendering.
  • Clock content overflowed window - "00:00:00" = 96px (8×12) but was drawn at X=22 in 108px content area. Repositioned to X=6 for proper centering.
  • Launcher help text caused white boxes - "W/S/Arrows: Select" = 216px (18×12), far too wide for window. Removed help text from launcher.

Added (Builds 127-134) - Mouse Cursor, Window Dragging, Drawing Context

  • XOR Mouse Cursor - 8x10 arrow sprite drawn with plot_pixel_xor (self-erasing)

    • Cursor hide/show with cursor_locked flag for flicker-free rendering
    • Visible on all backgrounds (white on black, black on white)

  • Window Title Bar Dragging - Click and drag windows by title bar

    • Three-layer architecture: IRQ12 detection → drag state machine → deferred processing
    • mouse_hittest_titlebar checks all visible windows for click hits
    • mouse_drag_update tracks offset and target position
    • mouse_process_drag called from event_get_stub (safe from reentrancy)

  • OS-Managed Content Preservation - Window content saved during drags

    • Scratch buffer at segment 0x5000 stores CGA pixel data
    • Byte-aligned save/restore with min(old_bpr, new_bpr) for cross-boundary moves
    • Apps don't need to redraw when their window is dragged

  • Window Drawing Context (APIs 31-32) - Apps use window-relative coordinates

    • win_begin_draw activates context for a window handle
    • win_end_draw deactivates context
    • APIs 0-6 automatically translate BX/CX from (0,0)=content-top-left to absolute screen

  • Text Width Measurement (API 33) - gfx_text_width returns string width in pixels

  • gfx_draw_string_inverted (API 6) - Fixed to use caller_ds for string access

    • Was reading from kernel segment (DS=0x1000) instead of app's segment
    • Caused white garbage boxes when launcher drew help text

Changed (Builds 127-134)

  • API table moved from 0x0F00 to 0x0F80 (more code space)
  • API count increased from 30 to 34 (functions 30-33)
  • Mouse enabled by default at boot (was disabled)
  • Launcher binary: 1304 → 1069 bytes (removed debug code and help text)
  • Clock window: W=90 → W=110 with centered time display at X=6

Added (Build 054) - Hard Drive / FAT16 Support

  • FAT16 Filesystem Driver - Read-only support for hard drives

    • fat16_mount - Mount FAT16 partition from MBR/partition table
    • fat16_open - Open files from FAT16 root directory
    • fat16_read - Read file data following FAT16 cluster chains
    • fat16_get_next_cluster - 16-bit FAT entry reading (simpler than FAT12's 12-bit)
    • fat16_read_sector - Sector read with INT 13h LBA extensions + CHS fallback

  • IDE/ATA Direct Access Driver - Fallback for BIOS issues

    • ide_detect - Detect IDE drive presence via IDENTIFY command
    • ide_wait_ready - Wait for drive ready (BSY clear, DRDY set)
    • ide_read_sector - Direct port I/O read (ports 0x1F0-0x1F7)
    • Supports LBA addressing mode

  • HD Boot Support - Boot UnoDOS directly from hard drive

    • boot/mbr.asm - Master Boot Record with partition table parsing
    • boot/vbr.asm - Volume Boot Record with FAT16 BPB
    • boot/stage2_hd.asm - HD kernel loader (finds KERNEL.BIN on FAT16)
    • Standard MBR relocation to 0x0600 for VBR loading

  • HD Image Creation Tools

    • tools/create_hd_image.py - Create 64MB FAT16 bootable HD image
    • tools/hd.ps1 - PowerShell script to write HD image to CF cards
    • Apps automatically included: KERNEL.BIN, LAUNCHER.BIN, CLOCK.BIN, BROWSER.BIN, MOUSE.BIN, TEST.BIN

  • New Makefile Targets

    • make hd-image - Build bootable FAT16 HD image
    • make run-hd - Test HD image in QEMU

Changed

  • Filesystem stubs now route by drive type:
    • Drive 0 (A:) -> FAT12 driver (mount handle 0)
    • Drive 0x80+ (HD) -> FAT16 driver (mount handle 1)
  • Kernel size increased to accommodate FAT16/IDE drivers

Technical Details (HD Driver - Build 054)

  • Partition Table Parsing

    • MBR at sector 0, partition table at offset 0x1BE
    • Supports FAT16 partition types: 0x04, 0x06, 0x0E
    • Hidden sectors field used for partition-relative LBA

  • INT 13h Extensions

    • Uses AH=42h (extended read) with disk address packet
    • Falls back to CHS conversion for older BIOSes
    • Drive geometry queried via AH=08h

  • IDE Port I/O Protocol

    • Primary controller: 0x1F0-0x1F7
    • Status polling: Wait for BSY=0, DRDY=1
    • LBA mode via 0xE0 in drive/head register
    • 256-word (512-byte) sector transfer via REP INSW

[3.12.0] - 2026-01-28

Added (Build 053) - PS/2 Mouse Driver

  • PS/2 Mouse Driver - Foundation 1.7 complete

    • INT 0x74 (IRQ12) mouse interrupt handler
    • 8042 keyboard controller interface (ports 0x60/0x64)
    • 3-byte packet protocol parsing with sync bit detection
    • Automatic mouse detection at boot
    • Position tracking clamped to screen (0-319 X, 0-199 Y)
    • Button state tracking (left, right, middle)
    • Posts EVENT_MOUSE (type 4) to event queue

  • New Mouse APIs (27-29)

    • mouse_get_state (API 27) - Returns BX=X, CX=Y, DL=buttons, DH=enabled
    • mouse_set_position (API 28) - Sets cursor position
    • mouse_is_enabled (API 29) - Checks if mouse available

  • MOUSE.BIN Test Application (578 bytes)

    • Window-based UI with mouse cursor tracking
    • Displays '+' cursor that follows mouse position
    • Shows '*' when button pressed
    • Displays X,Y coordinates
    • Gracefully handles "no mouse detected"
    • ESC to exit

Added (Build 042) - Dynamic Discovery & Browser

  • fs_readdir API (Index 26) - Kernel directory iteration
  • Dynamic App Discovery - Launcher scans for .BIN files
  • BROWSER.BIN - File browser showing all files with sizes (564 bytes)

Fixed (Builds 042-052)

  • Build 051: Browser ESC doesn't work - Added STI, use JC pattern
  • Build 052: Cleanup - Removed debug code

Added (Build 010-041) - Window Manager

  • Window Manager - Second Core Services feature (v3.12.0)

    • win_create_stub (API 19) - Create new window with position, size, title, and flags
    • win_destroy_stub (API 20) - Destroy window and clear its area
    • win_draw_stub (API 21) - Redraw window frame (title bar and border)
    • win_focus_stub (API 22) - Bring window to front (set z_order to 15, demote others)
    • win_move_stub (API 23) - Move window to new position
    • win_get_content_stub (API 24) - Get content area bounds for app drawing
    • window_table structure tracks up to 16 windows (512 bytes)
    • Window structure (32 bytes): state, flags, x, y, width, height, z_order, owner_app, title

  • Window Visual Design

    • 10-pixel white title bar with centered title text
    • 1-pixel white border around window
    • Content area calculation: accounts for title bar and borders
    • Window flags: WIN_FLAG_TITLE (show title bar), WIN_FLAG_BORDER (show border)

  • 'W' key handler in keyboard demo

    • Press 'W' to create a test window at (50, 30) with size 200x100
    • Displays "Window: OK" or "Window: FAIL" status message

Fixed

  • gfx_clear_area_stub - Was previously a no-op stub, now properly clears rectangular areas
    • Implements pixel-by-pixel clearing to background color
    • Required for window background clearing

Changed

  • API table expanded from 19 to 30 functions (Builds 010-053)
  • API table padding increased from 0x0900 to 0x0B00 (Build 053 - mouse driver code size)
  • Keyboard demo prompt updated to show W key option: "ESC=exit F=file L=app W=win:"

Technical Details (PS/2 Mouse - Build 053)

  • PS/2 mouse packet format:
    • Byte 0: YO XO YS XS 1 M R L (overflow, sign, sync bit, buttons)
    • Byte 1: X movement delta (8-bit, sign-extended with XS)
    • Byte 2: Y movement delta (8-bit, sign-extended with YS)
  • IRQ12 requires EOI to both slave PIC (0xA0) and master PIC (0x20)
  • Sync bit (bit 3) in first byte ensures packet alignment
  • AUXB bit (0x20) in status port distinguishes mouse from keyboard data

Technical Details (Window Manager)

  • Window structure (32 bytes):

    • Offset 0: State (0=free, 1=visible, 2=hidden)
    • Offset 1: Flags (bit 0: has_title, bit 1: has_border)
    • Offset 2-3: X position (0-319)
    • Offset 4-5: Y position (0-199)
    • Offset 6-7: Width in pixels
    • Offset 8-9: Height in pixels
    • Offset 10: Z-order (0=bottom, 15=top)
    • Offset 11: Owner app handle (0xFF = kernel)
    • Offset 12-23: Title (11 chars + null)
    • Offset 24-31: Reserved

  • Content area calculation:

    • Content X = Window X + 1 (border)
    • Content Y = Window Y + 10 (titlebar) + 1 (border)
    • Content Width = Window Width - 2 (borders)
    • Content Height = Window Height - 12 (titlebar + borders)

Constraints (v3.12.0)

  • No overlapping windows (windows must not overlap)
  • No dragging (win_move is API-only, no mouse drag)
  • No close button (destroy via API only)
  • White only (title bar uses white, no inverse video)

Future Enhancements

  • v3.13.0: Mouse support for window interaction
  • v3.14.0: Window dragging via mouse
  • v3.15.0: Overlapping window redraw

[3.11.0] - 2026-01-25

Added

  • Application Loader - First Core Services feature (v3.11.0)

    • app_load_stub (API 17) - Load .BIN applications from FAT12 into heap memory
    • app_run_stub (API 18) - Execute loaded applications via far CALL
    • app_table structure tracks up to 16 loaded applications (512 bytes)
    • Entry includes: state, priority, code segment/offset, stack (for future multitasking)
    • BIOS drive number support (0x00=A:, 0x01=B:, 0x80=C:, etc.)

  • Test Application Framework

    • apps/hello.asm - Simple test app that draws 'H' pattern to verify loader
    • tools/create_app_test.py - Creates FAT12 floppy with HELLO.BIN
    • make apps target to build applications
    • make test-app target to test app loader in QEMU

  • 'L' key handler in keyboard demo

    • Press 'L' to trigger app loader test
    • Prompts to insert app disk
    • Loads and runs HELLO.BIN from disk

Fixed (Build 008)

  • Keyboard ISR register corruption - INT 09h handler was modifying DX register without saving/restoring it, causing display corruption on real hardware
    • Added push/pop dx to int_09_handler
  • Error code display position - Error digit was drawn at X=100, overlapping with 'I' in "FAIL". Moved to X=136 (after 11-character string)

Fixed (Build 009)

  • App loader filename format - fat12_open expects "HELLO.BIN" (with dot separator) but kernel was passing "HELLO BIN" (raw FAT 8.3 format without dot)
    • Changed .app_filename to include dot separator
    • fat12_open parses the dot to split name/extension correctly
  • Dynamic build numbers - Version and build strings are now generated from files
    • BUILD_NUMBER file contains current build number
    • VERSION file contains version string
    • Makefile generates kernel/build_info.inc before assembly
    • make bump-build increments build number for next build

Changed

  • API table expanded from 17 to 19 functions
  • Keyboard demo prompt updated to show L key option

Technical Details

  • App calling convention:

    • Entry point at offset 0x0000 within loaded segment
    • Kernel calls app via far CALL
    • App returns via RETF with return code in AX
    • Apps can discover kernel API via INT 0x80 (returns ES:BX = API table pointer)

  • Memory layout:

    • Kernel at 0x1000:0000 (28KB)
    • Heap at 0x1400:0000 (apps loaded here via mem_alloc)

  • App table entry (32 bytes):

    • Offset 0: State (0=free, 1=loaded, 2=running, 3=suspended)
    • Offset 2: Code segment
    • Offset 4: Code offset (entry point)
    • Offset 6: Code size
    • Offset 8-10: Stack segment/pointer (for future multitasking)
    • Offset 12-22: Filename (8.3 format)

Future Enhancements Prepared

  • App table includes state field for cooperative multitasking
  • Stack segment/pointer fields for context switching
  • Priority field for future scheduler

[3.10.1] - 2026-01-24

Added

  • Multi-cluster file reading - FAT12 driver now reads files larger than 512 bytes

    • get_next_cluster() function reads FAT12 entries and follows cluster chains
    • Handles 12-bit FAT entries with even/odd cluster logic
    • FAT sector caching (512-byte fat_cache buffer + fat_cache_sector tracker)
    • Reads end-of-chain markers (0xFF8-0xFFF) to detect file end

  • Enhanced test infrastructure

    • tools/create_multicluster_test.py - generates 1024-byte test files
    • Test file spans 2 clusters with "CLUSTER 1:" and "CLUSTER 2:" markers
    • FAT chain validation: cluster 2 → cluster 3 → EOF
    • make test-fat12-multi target for testing
    • fs_read_buffer expanded from 512 to 1024 bytes

  • Hardware debugging documentation

    • docs/FAT12_HARDWARE_DEBUG.md - complete debugging process documentation

Fixed

  • Stack cleanup bug in fat12_open .found_file (Critical)

    • DS register pushed during search loop wasn't being popped in .found_file path
    • Caused system hang after finding file
    • Fixed by adding add sp, 2 for DS cleanup

  • LBA to CHS conversion in fat12_read (Critical)

    • Original code used bitmasks instead of proper division
    • DH (head) was never calculated
    • ES segment wasn't set for INT 13h read
    • BX (buffer pointer) was clobbered during division
    • Fixed with proper formula matching fat12_open's working code

  • Simplified attribute reading in fat12_open

    • Removed unnecessary ES segment override
    • DS is already 0x1000 in the search loop

Changed

  • fat12_read() rewritten for multi-cluster support

    • Now loops through cluster chain until EOF or all bytes read
    • Reads each cluster sequentially into bpb_buffer
    • Copies data to user buffer and advances pointer (ES:DI) automatically
    • Updates file position correctly for multi-cluster reads

  • Debug code removed for release

    • Removed D:, S:, A:, F: debug output from fat12_open
    • Removed comparison result (=/!) debug output
    • Removed unused debug strings (.dbg_dir, .dbg_srch, etc.)
    • Build string changed from "debug11" to "release"

Technical Details

  • FAT12 cluster chain algorithm:

    • Calculate FAT offset: (cluster × 3) / 2
    • Determine FAT sector: reserved_sectors + (offset / 512)
    • Cache FAT sector if not already loaded
    • Read 2 bytes from FAT at offset
    • If cluster is even: value = word & 0x0FFF
    • If cluster is odd: value = word >> 4
    • Check for end-of-chain: value >= 0xFF8

  • LBA to CHS conversion for 1.44MB floppy (18 sectors/track, 2 heads):

    • Sector: (LBA % 18) + 1
    • Head: (LBA / 18) % 2
    • Cylinder: LBA / 36

Hardware Verified

  • ✅ Tested on HP Omnibook 600C (486DX4-75)
  • ✅ Mount: OK
  • ✅ Open TEST.TXT: OK
  • ✅ Read: OK (multi-cluster)
  • ✅ C1:A C2:B displayed correctly

Testing

make test-fat12-multi      # Test with 1024-byte file
# Boot, press F, swap to test floppy
# Expected output: Mount: OK, Open: OK, Read: OK, C1:A C2:B

Notes

  • This release marks completion of FAT12 filesystem on real hardware
  • Multi-cluster support enables loading applications larger than 512 bytes
  • Critical foundation for Application Loader (v3.11.0)

[3.10.0] - 2026-01-23

Added

  • Foundation 1.6: Filesystem Abstraction Layer + FAT12 Driver (Complete)

    • Filesystem driver abstraction (VFS-like interface)
    • FAT12 filesystem driver (boot sector BPB parsing, directory search, file reading)
    • Filesystem API functions added to kernel API table:
      • fs_mount_stub() - Mount filesystem on drive (API offset 12)
      • fs_open_stub() - Open file by name (API offset 13)
      • fs_read_stub() - Read file contents (API offset 14)
      • fs_close_stub() - Close file handle (API offset 15)
      • fs_register_driver_stub() - Register loadable driver (API offset 16, reserved for Tier 2/3)
    • File handle table (16 handles, 32 bytes each = 512 bytes)
    • BPB cache for filesystem metadata (512 bytes)
    • 8.3 filename support (FAT12 directory entry parsing)
    • Root directory search (up to 224 entries on 360KB floppy)
    • Single-cluster file reading (512 bytes per cluster)
    • Error handling with error codes: FS_OK, FS_ERR_NOT_FOUND, FS_ERR_NO_DRIVER, FS_ERR_READ_ERROR, etc.

  • Three-Tier Architecture Design

    • Tier 1: Boot and run from single 360KB floppy (FAT12 built-in)
    • Tier 2: Multi-floppy system with loadable drivers (FAT16/FAT32 modules)
    • Tier 3: HDD installation with installer tool and bootloader writer
    • Driver registration hooks for future loadable filesystem modules

  • Test Infrastructure

    • FAT12 test floppy creation script (Python)
    • TEST.TXT file on FAT12 image for validation
    • test_filesystem() function demonstrates fs_mount/open/read/close

Changed

  • Kernel expanded from 24KB to 28KB (48 → 56 sectors)

    • Accommodates FAT12 driver implementation (~2.7 KB)
    • New size: 28,672 bytes (28KB)
    • Stage2 loader updated to load 56 sectors
    • Still 85%+ free space remaining (estimated ~3.6 KB used)

  • Kernel API table relocated

    • Moved from offset 0x0500 (1280 bytes) to 0x0800 (2048 bytes)
    • Provides 768 bytes additional headroom for future code
    • API table now at 0x1000:0x0800
    • Function count expanded from 12 to 17 slots

  • Entry point modified

    • Replaced keyboard_demo with test_filesystem() for v3.10.0 testing
    • Can be reverted to keyboard_demo after filesystem validation

Technical Details

  • FAT12 implementation:

    • Reads boot sector (sector 0) via BIOS INT 13h
    • Parses BPB (BIOS Parameter Block): bytes_per_sector, sectors_per_cluster, root_dir_entries, etc.
    • Calculates root_dir_start and data_area_start from BPB
    • Searches root directory (14 sectors on 360KB floppy)
    • Converts user filename to 8.3 FAT format (space-padded)
    • Finds matching directory entry, extracts starting cluster and file size
    • Reads file data from cluster (sector = data_start + (cluster-2) * sectors_per_cluster)
    • Allocates file handle from 16-entry table
    • Current limitations: read-only, single cluster per read, position=0 only

  • Filesystem abstraction:

    • Driver structure with function pointers (mount, open, read, close, list_dir, etc.)
    • Driver registry for up to 4 filesystem drivers
    • Auto-detection mechanism (tries each registered driver's detect function)
    • Mount table (4 entries, 16 bytes each) for active filesystem mounts
    • File handle table (16 entries, 32 bytes each) for open files

  • Size impact:

    • Abstraction layer: ~400 bytes
    • FAT12 driver: ~1,200 bytes
    • Data structures: ~1,088 bytes (mount table, file table, BPB cache, read buffer)
    • Total: ~2,688 bytes
    • Remaining kernel space: ~25 KB free (87% available)

Implementation

  • fat12_mount(): Reads boot sector, parses BPB, calculates layout
  • fat12_open(): Searches root directory, converts filename to 8.3, allocates handle
  • fat12_read(): Reads cluster data, copies to user buffer, updates position
  • fat12_close(): Marks file handle as free
  • fs_mount_stub(): Calls fat12_mount for drive 0, returns mount handle
  • fs_open_stub(): Validates mount handle, calls fat12_open
  • fs_read_stub(): Validates file handle, calls fat12_read
  • fs_close_stub(): Validates file handle, calls fat12_close

Foundation Layer Progress

  • ✓ System Call Infrastructure (v3.3.0)
  • ✓ Graphics API (v3.4.0)
  • ✓ Memory Allocator (v3.5.0)
  • ✓ Kernel Expansion to 24KB → 28KB (v3.6.0 → v3.10.0)
  • ✓ Aggressive Optimization (v3.7.0)
  • ✓ Keyboard Driver (v3.8.0)
  • ✓ Event System (v3.9.0)
  • ✓ Filesystem Abstraction + FAT12 (v3.10.0) - JUST COMPLETED

What's Next

Foundation Layer complete! Next phases:

  1. Core Services (v3.11.0-v3.13.0): App Loader, Window Manager
  2. Standard Library (v3.14.0): graphics.lib, unodos.lib for C development
  3. Tier 2/3 Support: Multi-floppy loading, HDD installation, FAT16/FAT32 drivers

Known Limitations

  • Read-only filesystem (no write support)
  • Single cluster reads only (512 bytes max)
  • No multi-cluster file spanning support
  • No subdirectory support (root directory only)
  • No long filename support (8.3 only)
  • File position fixed at 0 (no seek support)

These limitations are acceptable for v3.10.0 foundation. Advanced features will be added in future versions.

[3.9.0] - 2026-01-23

Added

  • Foundation 1.5: Event System (Complete)
    • Circular event queue (32 events, 3 bytes each = 96 bytes)
    • Event structure: type (byte) + data (word)
    • post_event() function for posting events to queue
    • event_get_stub() - Non-blocking event retrieval (API offset 8)
    • event_wait_stub() - Blocking event wait (API offset 9)
    • Event types: KEY_PRESS (1), KEY_RELEASE (2), TIMER (3), MOUSE (4)
    • Keyboard integration: INT 09h now posts KEY_PRESS events

Changed

  • Keyboard Demo Updated to Use Event System
    • Now uses event_wait_stub() instead of kbd_wait_key()
    • Demonstrates event-driven programming model
    • Updated instruction text: "Uses: Event System + Graphics API"
    • Updated exit message: "Event demo complete!"
    • Validates event system integration with keyboard driver

Technical Details

  • Event queue: 32-event circular buffer (96 bytes total)
  • Each event: 1 byte type + 2 bytes data
  • Queue management: head/tail pointers with wraparound at 32
  • Keyboard events: ASCII character stored in data field
  • Backward compatibility: kbd_getchar/kbd_wait_key still available
  • Dual posting: Keys stored in both keyboard buffer and event queue
  • Event types extensible for future timer, mouse, custom events

Implementation

  • post_event(): Adds event to tail of queue, advances tail pointer
  • event_get_stub(): Removes event from head, returns type and data
  • event_wait_stub(): Loops on event_get_stub() until event available
  • INT 09h handler: Calls post_event() after storing key in buffer
  • Variables: event_queue[96], event_queue_head, event_queue_tail

Foundation Layer Progress

  • ✓ System Call Infrastructure (v3.3.0)
  • ✓ Graphics API (v3.4.0)
  • ✓ Memory Allocator (v3.5.0)
  • ✓ Kernel Expansion to 24KB (v3.6.0)
  • ✓ Aggressive Optimization (v3.7.0)
  • ✓ Keyboard Driver (v3.8.0)
  • ✓ Event System (v3.9.0) - JUST COMPLETED

What's Next

Foundation Layer is now complete! Next phase: Standard Library (graphics.lib, unodos.lib)

[3.8.0] - 2026-01-23

Added

  • Foundation 1.4: Keyboard Driver (Complete)

    • INT 09h keyboard interrupt handler with proper PIC EOI signaling
    • Scan code to ASCII translation tables (normal and shifted)
    • Modifier key state tracking (Shift, Ctrl, Alt)
    • 16-byte circular buffer for keyboard input
    • Non-blocking kbd_getchar() function (API offset 10)
    • Blocking kbd_wait_key() function (API offset 11)
    • Support for alphanumeric keys, punctuation, and special keys
    • Proper handling of key press and release events

  • Interactive Keyboard Demo (Foundation Layer Integration Test)

    • Tests Graphics API + Keyboard Driver integration
    • Real-time keyboard input echo to screen
    • Displays prompt and instructions on boot
    • Handles special keys: ESC (exit), Enter (newline), Backspace (cursor back)
    • Auto-wraps at screen edges
    • Demonstrates API table function calls working in practice

Technical Details

  • INT 09h handler chains to original BIOS handler after processing
  • Two 96-byte scan code translation tables (normal and shifted)
  • Circular buffer prevents key loss during high-frequency input
  • API table expanded: 10 → 12 function slots
  • Estimated size: ~800 bytes (keyboard driver code + translation tables)
  • Variables added: old_int9_offset/segment, kbd_buffer[16], buffer pointers, modifier states
  • Interrupts enabled via STI after keyboard initialization

Implementation

  • install_keyboard(): Saves original INT 9h vector, installs handler, initializes buffer
  • int_09_handler(): Reads scan code (port 0x60), tracks modifiers, translates to ASCII, stores in buffer
  • kbd_getchar(): Returns next character from buffer (0 if empty)
  • kbd_wait_key(): Blocks until key available, returns character
  • Translation supports: A-Z, 0-9, punctuation, Escape, Backspace, Tab, Enter, Space

Foundation Layer Progress

  • ✓ System Call Infrastructure (v3.3.0)
  • ✓ Graphics API (v3.4.0)
  • ✓ Memory Allocator (v3.5.0)
  • ✓ Kernel Expansion to 24KB (v3.6.0)
  • ✓ Aggressive Optimization (v3.7.0)
  • ✓ Keyboard Driver (v3.8.0)
  • ⏳ Event System (v3.9.0 - Next)

[3.7.0] - 2026-01-23

Changed

  • Aggressive Kernel Optimization (Pre-Foundation 1.4/1.5)
    • Removed test functions (test_int_80, test_graphics_api): ~200 bytes freed
    • Removed 21 character alias definitions (char_W, char_E, etc.)
    • Optimized all graphics API functions: replaced pusha/popa with targeted register saves
    • Optimized gfx_draw_rect_stub: eliminated ~80 bytes of redundant push/pop operations
    • Optimized plot_pixel_white: removed variable storage (pixel_save_x/y), stack-only implementation
    • Optimized setup_graphics: tighter BIOS call sequence
    • Optimized install_int_80: minimal register preservation
    • Welcome message now uses gfx_draw_string (string-based) instead of individual char draws

Technical Details

  • Kernel code: 2436 → 2416 bytes (20 bytes from optimization, ~200 from removal)
  • Total space gained: ~220 bytes
  • Available in 24KB kernel: 22,160 bytes (sufficient for Foundation 1.4 + 1.5 + future features)
  • Removed variables: pixel_save_x, pixel_save_y
  • Removed test chars: test_W_char, test_eq_char
  • Optimized functions maintain identical behavior, purely size/speed improvements

Rationale

  • Maximize space for Foundation 1.4 (Keyboard Driver ~800B) and 1.5 (Event System ~400B)
  • Eliminate production overhead from debug/test code
  • Optimize frequently-called graphics primitives
  • Prepare for remaining Foundation Layer implementation

[3.6.0] - 2026-01-23

Changed

  • Kernel Expansion: 16KB → 24KB
    • Kernel size increased from 16384 bytes (32 sectors) to 24576 bytes (48 sectors)
    • Provides headroom for Foundation 1.4 (Keyboard Driver, ~800 bytes) and Foundation 1.5 (Event System, ~400 bytes)
    • Heap start moved from 0x1400:0000 to 0x1600:0000
    • Available heap reduced from 540KB to 532KB (loses 8KB)

Technical Details

  • Modified boot/stage2.asm: KERNEL_SECTORS 32 → 48
  • Modified kernel/kernel.asm: Final padding 16384 → 24576
  • New memory layout:
    • 0x1000:0x0000 - Kernel (24KB, was 16KB)
    • 0x1600:0x0000 - Heap start (was 0x1400:0x0000)
    • ~532KB available for applications (was 540KB)
  • Kernel headroom: ~7KB for future Foundation Layer components

Rationale

  • v3.5.0 reached exact 16KB capacity with Memory Allocator
  • Foundation 1.4 and 1.5 require additional ~1200 bytes minimum
  • 24KB expansion is conservative, leaves room for future enhancements
  • 8KB heap reduction is negligible (still 532KB for apps)
  • See docs/MEMORY_LAYOUT.md for detailed analysis

[3.5.0] - 2026-01-23

Added

  • Memory Allocator (Foundation 1.3)
    • malloc(size): Allocate memory dynamically
    • free(ptr): Free allocated memory
    • First-fit allocation algorithm
    • Heap at 0x1400:0000, extends to ~640KB limit
    • Block header structure (size + flags)
    • Integrated with API table (offsets 6, 7)

Technical Details

  • Memory block header: 4 bytes [size:2][flags:2]
    • size: Total block size including header
    • flags: 0x0000 (free) or 0xFFFF (allocated)
  • First-fit search algorithm for allocation
  • Automatic heap initialization on first malloc
  • Initial heap block: ~60KB (0xF000 bytes)
  • 4-byte aligned allocations

Implementation

  • malloc(AX=size) → AX=pointer (offset from 0x1400:0000), 0 if failed
  • free(AX=pointer) → frees memory block
  • Heap starts at segment 0x1400 (linear 0x14000)
  • Applications use ES=0x1400 + offset for memory access

Size Impact

  • Memory allocator: ~600 bytes
  • Kernel size: Still 16KB (16384 bytes exact)
  • Remaining capacity: ~0 bytes (at maximum)

[3.4.0] - 2026-01-23

Added

  • Graphics API Abstraction (Foundation 1.2)
    • gfx_draw_pixel: Wraps plot_pixel_white for API table access
    • gfx_draw_char: Character rendering with coordinate parameters
    • gfx_draw_string: Null-terminated string rendering
    • gfx_draw_rect: Rectangle outline drawing
    • gfx_draw_filled_rect: Filled rectangle drawing
    • gfx_clear_area: Clear rectangular area (stub for now)

Fixed

  • Welcome message typo: "WELLCOME" → "WELCOME"

Technical Details

  • All graphics functions accessible via kernel API table
  • Register-based calling convention:
    • gfx_draw_pixel(CX=X, BX=Y, AL=color)
    • gfx_draw_char(BX=X, CX=Y, AL=ASCII)
    • gfx_draw_string(BX=X, CX=Y, SI=string_ptr)
    • gfx_draw_rect(BX=X, CX=Y, DX=width, SI=height)
    • gfx_draw_filled_rect(BX=X, CX=Y, DX=width, SI=height)
  • Kernel size: Still within 16KB limit

Hardware Testing

  • Tested on HP Omnibook 600C (486DX4-75)
  • INT 0x80 discovery working ✓
  • "OK" indicator displays correctly ✓

[3.3.0] - 2026-01-23

Added

  • System Call Infrastructure (Foundation 1.1)
    • INT 0x80 handler for system call discovery mechanism
    • Kernel API table at fixed address 0x1000:0x0500
    • Hybrid approach: INT 0x80 for discovery + Far Call Table for execution
    • API table header with magic number ('KA' = 0x4B41), version (1.0), function count
    • 10 stub functions for future implementation:
      • Graphics API (6 functions): draw_pixel, draw_rect, draw_filled_rect, draw_char, draw_string, clear_area
      • Memory management (2 functions): malloc, free
      • Event system (2 functions): get_event, wait_event
  • Visual test for INT 0x80 - displays "OK" at bottom right if successful

Technical Details

  • API table positioned at exactly offset 0x0500 (verified in binary)
  • Follows Windows 1.x/2.x, GEOS pattern for performance
  • Far Call approach saves ~40 cycles per call vs pure INT approach (~9% CPU at 4.77MHz)
  • Foundation for third-party application development
  • Enables future protected mode transition via thunking

Documentation

  • Added docs/ARCHITECTURE_PLAN.md - Complete architectural analysis and roadmap
  • Added docs/SYSCALL.md - System call performance analysis
  • Updated README.md with phase-based feature roadmap
  • Updated docs/SESSION_SUMMARY.md with architectural decisions

[3.2.0] - 2026-01-22

Changed

  • Major architectural change: Split kernel from stage2 loader
    • Stage2 is now a minimal 2KB loader with progress indicator
    • Kernel is a separate 16KB binary loaded at 0x1000:0000 (64KB mark)
    • Enables kernel to grow beyond 8KB limit
    • Future-proof architecture for XT through 486 hardware
  • Boot sequence now shows "Loading kernel" with dot progress bar
  • Removed text-mode debug output from bootloader (cleaner boot)
  • RAM display now shows correct memory usage (~20KB for loader+kernel)

Added

  • New kernel/ directory for OS code
  • kernel/kernel.asm - Main operating system (16KB)
  • Kernel signature verification ('UK' = 0x4B55)

Technical Details

  • Disk layout: Boot (1 sector) + Stage2 (4 sectors) + Kernel (32 sectors)
  • Stage2 loads kernel sector-by-sector with progress indicator
  • Kernel loaded at segment 0x1000 (linear address 0x10000)

[3.1.7] - 2026-01-22

Changed

  • Character demo redesigned for ASCII verification
    • Displays all 95 printable ASCII characters (32-126) in a 2-row grid
    • Row 1: characters 32-79 (48 chars) at Y=160
    • Row 2: characters 80-126 (47 chars) at Y=168
    • All characters remain visible during long pause (~100 delay cycles)
    • Then clears and repeats for continuous verification
  • Clear demo area expanded to 16 pixels height (Y=160-175) for 2 rows

[3.1.6] - 2026-01-22

Fixed

  • Clock and character demo now visible on HP Omnibook 600C
    • Added ES segment initialization in draw_clock and char_demo_loop
    • ES must point to 0xB800 (CGA video memory) for pixel plotting
  • Slowed down animations for 486/DSTN display compatibility
    • Increased delay_short to nested loop (~4 million iterations)
    • Character demo now visible on slow DSTN displays with ghosting

Changed

  • Clock moved to top-left corner (X=4, Y=4)
  • Character demo moved below welcome box (Y=160)
  • Removed MDA text mode support (CGA-only now)
  • Simplified video detection (no longer tracks video_type)

Added

  • Comprehensive coordinate visibility testing
  • Confirmed full 320x200 CGA area visible on Omnibook 600C
  • New documentation: ARCHITECTURE.md, FEATURES.md
  • Comprehensive README update

[3.1.5] - 2026-01-22

Fixed

  • Fixed graphical corruption of version text caused by overlapping elements
    • Clock moved to Y=40 (above white box which starts at Y=50)
    • Character demo moved to Y=120 (inside box, below version at Y=106)
    • Demo now starts at X=65 to stay within box boundaries (X=60-260)

[3.1.4] - 2026-01-22

Fixed

  • Clock and character demo now visible on HP Omnibook 600C
    • Clock moved to Y=60 (just above welcome message)
    • Character demo moved to Y=108 (just below version text)
    • Positions within known visible area (Y=4-106 confirmed visible)

Changed

  • Separated clock_loop as independent function
  • Added main_loop to coordinate clock and demo updates

[3.1.3] - 2026-01-22

Fixed

  • Character demo now visible on real hardware (moved from Y=165 to Y=130)
    • Accounts for display overscan on vintage hardware
    • Tested on HP Omnibook 600C

[3.1.2] - 2026-01-22

Added

  • Real-time clock display in top left corner
    • Reads time from CMOS RTC via BIOS INT 1Ah, AH=02h
    • Displays HH:MM:SS format using 4x6 small font
    • Updates continuously during character demo loop
    • Falls back to "--:--:--" if RTC unavailable
  • New functions: draw_clock, draw_bcd_small, clear_clock_area

[3.1.1] - 2026-01-22

Added

  • Character demo at boot: cycles through all ASCII characters (32-126)
    • Displays characters horizontally at bottom of screen using 4x6 font
    • Clears and repeats in an infinite loop
    • Visual delay between characters for effect
  • New functions: char_demo_loop, clear_demo_area, delay_short

Changed

  • Moved RAM status display from bottom right to top right corner

[3.1.0] - 2026-01-22

Added

  • Complete ASCII bitmap font set (characters 32-126)
    • 8x8 font in boot/font8x8.asm (95 characters, 760 bytes)
    • 4x6 small font in boot/font4x6.asm (95 characters, 570 bytes)
  • Generic text rendering functions for any ASCII string:
    • draw_string_8x8: Render null-terminated string with 8x8 font
    • draw_string_4x6: Render null-terminated string with 4x6 font
    • draw_ascii_8x8: Render single ASCII character with 8x8 font
    • draw_ascii_4x6: Render single ASCII character with 4x6 font
  • Font tables accessible via font_8x8 and font_4x6 labels
  • Legacy character aliases (char_H, char_E, etc.) maintained for compatibility

Changed

  • Font data moved from inline definitions to separate include files
  • Makefile updated with NASM include path for font files

[3.0.1] - 2026-01-22

Added

  • RAM status display in bottom right corner of screen
    • Shows total RAM (from BIOS INT 12h)
    • Shows estimated used memory (~10K for boot code)
    • Shows free memory (total - used)
  • New 4x6 small character bitmaps: digits 1-9, R, A, M, K, U, F, s, e, d, r, colon
  • draw_number_small function for rendering numbers with small font

[3.0.0] - 2026-01-22

Changed

  • Major version bump to UnoDOS 3
  • New startup message: "Welcome to UnoDOS 3!" with version number below
  • Added 4x6 small font for version display
  • New 8x8 character bitmaps: C, M, T, U, N, S, 3
  • New 4x6 small character bitmaps: v, 3, 0, .

[0.2.4] - 2026-01-22

Fixed

  • Graphics corruption bug: BIOS teletype output (INT 10h AH=0Eh) was being called after switching to CGA graphics mode, causing text to render as stray pixels in the top-left corner of the screen
  • Removed post-graphics print_string call that caused the corruption
  • Hello World graphics now display correctly with no stray pixels

[0.2.3] - 2026-01-22

Added

  • Pre-built floppy images now included in repository
    • build/unodos.img (360KB)
    • build/unodos-144.img (1.44MB)

Changed

  • Updated .gitignore to track final images, ignore intermediate build files

[0.2.2] - 2026-01-22

Fixed

  • QEMU boot compatibility: Changed machine type from -machine pc to -M isapc for proper PC/XT BIOS boot behavior
  • Boot now works correctly in QEMU with graphical Hello World display

Changed

  • Makefile now uses isapc machine type for all QEMU targets

[0.2.1] - 2026-01-22

Added

  • Windows floppy write utilities
    • tools/writeflop.bat - Batch script for Windows command prompt
    • tools/Write-Floppy.ps1 - PowerShell script with verification
    • Both support 360KB and 1.44MB images
    • Require Administrator privileges for raw disk access

[0.2.0] - 2026-01-22

Added

  • Boot sector (boot/boot.asm) - 512-byte IBM PC compatible boot loader
    • Loads from floppy drive (BIOS INT 13h)
    • Debug messages during boot process
    • Loads 8KB second stage from sectors 2-17
    • Validates second stage signature before jumping
  • Second stage loader (boot/stage2.asm)
    • Memory detection via INT 12h
    • Video adapter detection (MDA/CGA/EGA/VGA)
    • CGA 320x200 4-color graphics mode
    • Graphical "HELLO WORLD!" with custom 8x8 bitmap font
    • MDA fallback with text-mode box drawing
  • Build system (Makefile)
    • make - Build 360KB floppy image
    • make floppy144 - Build 1.44MB floppy image
    • make run / make run144 - Test in QEMU
    • make debug - QEMU with monitor for debugging
    • make sizes - Show binary sizes
    • Dependency checking for nasm and qemu
  • Floppy write utility (tools/writeflop.sh)
    • Write images to physical floppy disks
    • Supports both 360KB and 1.44MB formats
    • Verification after write
    • Safety checks to prevent accidental overwrites

[0.1.0] - 2026-01-22

Added

  • Initial project setup
  • Project documentation (CLAUDE.md) with target specifications
  • Documentation structure (docs/, VERSION, CHANGELOG.md, README.md)
  • Target hardware: Intel 8088, 128KB RAM, MDA/CGA displays, floppy drive
  • Architecture defined: GUI-first OS with direct BIOS interaction, no DOS dependency