PackCom — C++ Reconstruction

Original: PackCom v0.75 Dev. by Jim Wright (WB4ZJV), 01/28/1987
Reconstruction: Portable C++17, cross-platform (Linux / macOS / Windows)

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Background

The three original files were compiled Turbo Pascal binaries produced by Borland Pascal circa 1985–1987. There was no source available — this C++ codebase was reconstructed entirely from the binary strings, control flow hints, variable names exposed in the debug output section, and the full set of UI prompts recovered from the overlay files.

Original file	Size	Role
PACKCOM.COM	44 KB	Main executable (Borland Pascal runtime + core code)
PACKCOM.000	11 KB	Overlay 0 – config menus, color setup, capture mode
PACKCOM.001	40 KB	Overlay 1 – YAPP transfer, scroll-back, file ops, I/O

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Features Reconstructed

All of these were confirmed from binary string extraction:

Terminal / Display

• Full-colour ANSI terminal (80×25 native; adapts to actual terminal size)
• AX.25 packet header detection and distinct colouring
• Keyboard/Digi echo detection — outgoing packets echoed back are highlighted differently from new incoming traffic
• Non-header packet colouring (connected station data, TNC responses)
• Keyword scanning with per-keyword foreground/background colours and optional audio beep (Special Effects)
• Windowed display system with border drawing (up to 8 nested windows)
• Split-screen view (ALT-V toggle)
• Auto-update mode toggle (Home key)

Scroll-Back Buffer

• Configurable line count (default 200, max ~9999)
• Interactive viewer with Up/Down/PgUp/PgDn navigation
• Text search with start-line specification
• Line-number jump

Serial / Comm

• COM1–COM4 (Linux: /dev/ttyS0–/dev/ttyS3)
• Baud: 300, 1200, 2400, 4800, 9600
• Data bits: 7 or 8; stop bits: 1 or 2; parity: None/Even/Odd
• Background I/O thread with ring buffers (SIN_BUF_SIZE = 4096, SOUT_BUF_SIZE = 4096 — matching the original Pascal variable names)
• DTR control, Carrier Detect polling, BREAK signal
• Per-byte and per-CRLF transmit delays
• Full/Half duplex toggle (ALT-F)

YAPP File Transfer

Complete state machine with all 12 states recovered verbatim:
Start → SendInit → SendHeader → SendData → SendEof → SendEOT
RcvWait → RcvHeader → RcvData → SndABORT → WaitAbtAck → RcdABORT

All 17 packet types (UK RR RF SI HD DT EF ET NR CN CA RI TX UU TM AF AT) and all 19 status messages recovered verbatim from the binary.

File Operations

• Capture mode (ALT-C): toggle on/off, prompts for filename, optional date/time stamps
• ASCII transmit (ALT-T): XON/XOFF flow, pause/cancel with any key
• File viewer (ALT-V): paginated view, split-screen option, byte/line progress display
• Directory listing (ALT-D): with free-bytes display
• Change directory/drive (ALT-N)
• Kill file (ALT-K): delete with confirmation

Configuration (PACKCOM.CNF)

22 options across two pages, all recovered from the config menu strings:

#	Flag	Option
1	P	Number of Stop Bits
2	P	Number of Data Bits
3	P	Parity Type
4	P	Baud Rate
5	P	Communication Port
7	X	Scroll Back Buffer Size
8		Incoming BELL (Ctrl-G)
9		Eliminate Blank Lines
10		Time Management Every N Minutes
11		Display Time
12		Change Color
14		1/1000 Sec delay after byte
15		1/1000 Sec delay after CRLF
16	X	Memory for DOS Programs (KB)
17		Default DOS Program
18	X	Set TNC Date and Time
19	X	Drive/Path to Overlays
20		Stream Switch Character
21		Carrier Detect = Connected?
22		BREAK → CMD mode?

P = requires ALT-P reconnect to take effect
X = requires restart to take effect

Keyboard / Macros (PACKCOM.KEY)

• Line mode and Char mode (ALT-Q toggle)
• Full cursor navigation: Home, End, Ctrl-Home, Ctrl-End, Ins, Del, Ctrl-Left/Right word tab, Ctrl-PgUp/PgDn history scroll
• 40 macro slots (F1–F10 × Unshifted / Shifted / Ctrl / Alt)
• Macro syntax: ] = CR, @x = TNC command char, ~ = 500ms delay, ; = comment

DOS Shell (ALT-E)

• Configurable memory allocation (option 16)
• Spawns configured program or the system shell
• EXIT returns to PackCom

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ALT-Key Command Reference

Key	Action
ALT-H	Help – comm buffer commands
ALT-C	Toggle capture mode
ALT-I	Configuration menu
ALT-P	Change comm parameters (reconnects port)
ALT-X	Exit PackCom
ALT-V	View file / toggle split screen
ALT-T	Transmit ASCII file (XON/XOFF)
ALT-Y	YAPP file transfer
ALT-D	Disk directory
ALT-N	New directory / drive
ALT-E	Execute DOS command
ALT-S	Scroll-back buffer processing
ALT-K	Kill (delete) file
ALT-M	Macro key definitions
ALT-Q	Toggle Line / Char keyboard mode
ALT-F	Toggle Full / Half duplex
ALT-B	Send BREAK
ALT-A	Alarms and special effects
ALT-O	Other commands (comm port info)
Home	Toggle auto-update of comm buffer

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Building

Prerequisites

• C++17 compiler: GCC 8+, Clang 7+, or MSVC 2019+
• POSIX: pthread library
• Windows: standard Win32 SDK (no extra dependencies)
• Optional: CMake 3.16+

Linux / macOS

# With Make
make

# Or with CMake
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make -j$(nproc)

Windows (MSVC)

mkdir build && cd build
cmake .. -G "Visual Studio 17 2022"
cmake --build . --config Release

Windows (MinGW)

make CXX=g++

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Running

./packcom          # normal start
./packcom /I       # reinitialize PACKCOM.CNF to defaults
./packcom --help   # usage

On Linux, serial ports require appropriate permissions:

sudo usermod -aG dialout $USER   # then log out and back in
# or for a single session:
sudo chmod 666 /dev/ttyS1

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File Structure

packcom/
├── CMakeLists.txt
├── Makefile
├── README.md
├── include/
│   ├── packcom.h      # types, constants, config structs, YAPP enums
│   ├── platform.h     # OS abstraction interface
│   ├── keys.h         # unified key codes
│   ├── serial.h       # serial port + ring buffers
│   ├── terminal.h     # windowed display + scroll-back
│   ├── input.h        # keyboard editor + macros
│   ├── config.h       # config load/save + all menus
│   ├── yapp.h         # YAPP transfer protocol
│   ├── fileops.h      # capture, ASCII tx, file view, dir, shell
│   └── app.h          # top-level application class
└── src/
    ├── main.cpp
    ├── platform.cpp
    ├── serial.cpp
    ├── terminal.cpp
    ├── input.cpp
    ├── config.cpp
    ├── yapp.cpp
    ├── fileops.cpp
    └── app.cpp

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Notes on Fidelity

• All user-visible strings (prompts, error messages, status lines, menu text) were extracted verbatim from the original binaries and are used unchanged in this reconstruction.
• The original used Borland Pascal's direct BIOS/DOS interrupt calls for screen I/O (INT 10h) and serial I/O (INT 14h / custom ISR). These are replaced with ANSI escape sequences (POSIX) or Win32 Console API.
• The original's async_intr_handler hardware ISR is replaced by a background std::thread polling loop with the same ring-buffer variables (sout_store_ptr, sout_read_ptr, sin_read_ptr, sin_buf_fill_cnt) implemented as std::atomic<int> indices.
• PACKCOM.WRD (keyword file) loading is stubbed — keywords are stored in PACKCOM.CNF in this version.
• The /I re-initialization flag is preserved.
• The TILT !!! fatal error handler from the original is not needed; C++ exceptions handle abnormal termination.

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License

This reconstruction is an independent clean-room reimplementation for historical preservation purposes. The original PackCom was freeware distributed in the amateur radio community (WB4ZJV, 1987).