Note: AI assistance has been employed in the development of this project. If this offends you, I'm sorry but I'm not changing anything

🖨️ Flashback Print Server Suite

Modern Cross-Platform Print Services for Legacy Host Systems

Flashback is a robust, high-performance suite that bridges legacy mainframe and minicomputer systems (MVS, z/OS, VMS, MPE, VM/CMS) to modern PDF generation and network printing infrastructure. Transform your vintage computing environment's print output into professional PDFs with full carriage control interpretation, email delivery, and web-based monitoring.

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✨ Key Features

🔌 Universal Connectivity

• Port 9100 (JetDirect) - Standard network printer protocol compatibility
• Raw TCP/IP Streams - Direct connection from any legacy system
• Bidirectional Communication - Client or server mode operation

📄 Advanced PDF Generation

• Configurable Orientation - Portrait or landscape output
• Professional Shading - Green bar, blue bar, or plain white backgrounds
• Automatic Job Numbering - Sequential tracking of print jobs

📧 Email Integration (experimental)

• Automatic PDF Delivery - Send generated PDFs directly to email recipients
• Template Variables - Dynamic subject and body customization
• Multiple Recipients - Semicolon-separated distribution lists
• SMTP Compatibility - Should work with Gmail, Office 365, SendGrid, and more (mostly untested)
• TLS/SSL Support - Secure email transmission

🖥️ Multiple Configuration Interfaces

• Console Application - Full-screen interactive TUI for device management
• 3270 Terminal Interface - Remote administration via TN3270 emulator (configuration only)
• WPF Desktop Application - Native Windows GUI with modern design
• WinUI Application - Next-generation Windows interface
• Web-based PDF Viewer - Browser-based viewing of generated PDFs (optional)

🔐 Enterprise Features

• Licensing System - Free tier (2 printers) No, I'm not charging for licenses; it was an experiment.
• Multi-Platform - Windows (x64) and Linux (x64/ARM64) support
• Background Services - Windows Service and Linux systemd integration
• Comprehensive Logging - Detailed operational history and debugging

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🏗️ Architecture

┌─────────────────────────────────────────────────────────────────┐
│                    Legacy Host Systems                          │
│  (MVS, z/OS, VM/CMS, VMS, MPE, Hercules, SimH, etc.)          │
└────────────────┬────────────────────────────────────────────────┘
                 │ TCP/IP connections and port 9100 RAW
                 ▼
┌─────────────────────────────────────────────────────────────────┐
│                  Flashback.Engine (Core Service)                │
│  • Connection Management    • Carriage Control Processing       │
│  • PDF Generation          • Email Delivery                     │
│  • Job Queuing             • Web PDF Viewer (optional)          │
└────────────────┬────────────────────────────────────────────────┘
                 │
                 ├──► PDF Files (Local/Network Storage)
                 ├──► Email (SMTP)
                 └──► Network Printers (Future)
                 
┌─────────────────────────────────────────────────────────────────┐
│              Optional: Flashback.Spooler                        │
│  Port 9100 Gateway for Modern Applications                      │
└─────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────────┐
│                  Configuration Tools                            │
│  • Console TUI    • 3270 Terminal (TN3270)    • WPF/WinUI GUI  │
└─────────────────────────────────────────────────────────────────┘

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🚀 Quick Start

Prerequisites

• Windows: Windows 10/11 (x64) with .NET 10 Runtime
• Linux: Ubuntu 20.04+, Debian 11+, RHEL 8+, or compatible (x64/ARM64)
• Network: TCP/IP connectivity between host and Flashback server
• Privileges: Administrator (Windows) or sudo (Linux) for service installation

Installation

Windows

You may use the windows installer for painless installation, or build yourself.

# 1. Clone or download the repository
git clone https://github.com/scomps/flashback.git
cd flashback

# 2. Build and publish
.\scripts\winpub.ps1

# 3. Install services (requires Administrator)
.\scripts\install_services_windows.ps1

# 4. Launch the tray controller
# Look for the Flashback icon in your system tray

Linux

# 1. Clone or download the repository
git clone https://github.com/scomps/flashback.git
cd flashback

# 2. Build and publish
chmod +x scripts/publish_linux.sh
./scripts/publish_linux.sh

# 3. Install services (requires sudo)
sudo ./scripts/install_services_linux.sh

# 4. Start the engine
sudo systemctl start flashback-engine
sudo systemctl status flashback-engine

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📖 Documentation

Core Components (Engine, 3270 config, and spooler can be run in the foreground)

Flashback.Engine

The heart of the system - a background service that:

• Listens for incoming print jobs from legacy hosts
• Processes carriage control sequences
• Generates professional PDF documents
• Delivers PDFs via email or file system
• Provides optional web-based PDF viewing

Configuration: devices.dat file in the application directory

Flashback.Spooler (Optional)

A Port 9100 (JetDirect) gateway that:

• Accepts print jobs from modern applications
• Spools jobs to disk with automatic cleanup
• Forwards jobs to Flashback.Engine for processing
• Provides retry logic and queue management

Use Case: Bridge modern Windows/Linux applications to Flashback

Flashback.Config.Console

Interactive terminal-based configuration utility:

• Full-screen TUI with keyboard navigation
• Add, edit, delete virtual printer devices
• Configure PDF rendering options
• Set up email delivery per device
• Cross-platform (Windows/Linux)

Flashback.Config.3270 (Optional)

Remote administration via TN3270 terminal emulator:

• Connect from any 3270 emulator (x3270, c3270, etc.)
• Manage device configuration remotely
• Password protection (SYSPW)
• Perfect for mainframe administrators
• Note: TN3270 protocol is used exclusively for this configuration tool, not for print data transmission

Default Port: 3270

Flashback.Config.WPF / WinUI

Native Windows GUI applications:

• Modern, intuitive interface
• Visual device management
• Email configuration wizard
• Real-time status monitoring
• Windows 10/11 optimized

Flashback.Tray

Windows system tray controller:

• Quick access to services
• Start/stop Engine and 3270 server
• View logs
• Launch configuration tools

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🔧 Configuration

Device Configuration

Each virtual printer device requires:

Field	Description	Example
Device Name	Unique identifier	PRINTER1
Description	Human-readable label	Mainframe Line Printer
Connection Type	Client (0) or Server (1)	0
Destination	IP:Port for connection	192.168.1.100:9000
Host OS	Source system type	MVS, VMS, Generic, etc.
PDF Enabled	Generate PDF output	true
Orientation	Portrait (0) or Landscape (1)	0
Shading	Green bar, Blue bar, or White	Green
Output Directory	PDF destination path	C:\Flashback\Output

Email Configuration (Per Device) EXPERIMENTAL

Field	Description	Example
Email Enabled	Enable automatic delivery	true
Recipients	Semicolon-separated addresses	user@example.com;admin@company.com
SMTP Server	Mail server hostname	smtp.gmail.com
SMTP Port	Mail server port	587 (TLS) or 465 (SSL)
Username	SMTP authentication user	sender@example.com
Password	SMTP authentication password	app-password
Use TLS	Enable encryption	true
From Address	Sender email	flashback@company.com
From Name	Sender display name	Flashback Print Server
Subject	Email subject (supports variables)	Print Job: {JobName}
Body	Email body (supports variables)	Attached is your print job.

Email Template Variables

• {JobName} - Generated PDF filename
• {DeviceName} - Virtual printer name
• {UserName} - Job submitter
• {PageCount} - Number of pages
• {DateTime} - Full timestamp
• {Date} - Date only
• {Time} - Time only

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🖥️ Host System Integration

Hercules (MVS, z/OS, VM/CMS)

Add printer definitions to your Hercules configuration file:

# Device  Type    Destination
000E      1403    192.168.1.100:9000 sockdev
000F      1403    192.168.1.100:9001 sockdev

SimH (PDP-11, VAX, MicroVAX)

Configure DZ11/DZV11 lines to connect to Flashback: In this case, our 'printer' is a hardcopy terminal on DZ line 0.

SET DZ LINES=8
ATTACH DZ LINE=0 8000
ATTACH DZ LINE=1 8001

Generic TCP/IP

Any system capable of TCP/IP can send print data:

# Direct connection
cat printfile.txt | nc 192.168.1.100 9000

# Or use telnet
telnet 192.168.1.100 9000 < printfile.txt

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📊 Licensing

Flashback operates in two tiers:

Tier	Capability	Use Case
FREE	Up to 2 concurrent printers	Personal, educational, non-commercial

To get a license, just ask. This has been a toy I wanted to play with, not a policy. To activate a license:

1. Obtain your flashback.lic file
2. Place it in the Flashback application directory
3. Restart the Flashback.Engine service

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🔒 Security Best Practices

Network Security

• Firewall Rules: Restrict access to Flashback ports to trusted host IPs only
• TLS/SSL: Always enable TLS for SMTP email delivery
• Port Isolation: Keep Engine ports on internal networks

Authentication

• 3270 Password: Always set a system password (SYSPW) for the 3270 configuration server
• File Permissions: Restrict access to devices.dat and flashback.lic files
• Email Credentials: Use app-specific passwords, not account passwords

Monitoring

• Log Review: Regularly check printers.log for suspicious activity
• Job Tracking: Monitor job numbers for unexpected patterns
• Service Status: Ensure services are running only when needed

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🐛 Troubleshooting

Connection Issues

Problem: Host cannot connect to Flashback

• Verify Flashback.Engine service is running
• Check firewall rules allow the configured port
• Confirm IP address and port in both host and Flashback configuration
• Review printers.log for connection attempts

Problem: Flashback cannot connect to host

• Ensure host system is listening on the configured port
• Verify network connectivity with ping or telnet
• Check if host firewall blocks incoming connections

PDF Generation Issues

Problem: PDFs are blank or malformed

• Verify correct Host OS setting (MVS vs VMS vs Generic)
• Check if source data includes proper carriage control
• Review PDF orientation setting (portrait vs landscape)
• Examine raw data in printers.log (debug mode)

Problem: Fonts look incorrect

• Ensure font files are present in Assets directory
• Verify PDF viewer supports embedded fonts
• Note: Font selection is not currently configurable; default font is used

Email Delivery Issues EXPERIMENTAL

NOTE GMAIL AND MANY COMMERCIAL EMAIL SERVICES WILL NOT ACCEPT MAIL FROM UNREGISTERED SECURE SMTP SERVERS.

Problem: Emails not sending

• Recognize that gmail and others will not accept SMTP from just anyone.
• Verify SMTP server, port, and credentials
• Check if TLS/SSL setting matches server requirements
• Ensure firewall allows outbound SMTP connections
• Review printers.log for SMTP error messages
• Test with a known-good email configuration first

Problem: Authentication failures

• Use app-specific passwords for Gmail, Office 365
• Verify username format (some servers require full email)
• Check if 2FA requires special authentication

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🛠️ Building from Source

Prerequisites

• .NET 10 SDK
• Git

Build Commands

# Clone repository
git clone https://github.com/scomps/flashback.git
cd flashback

# Restore dependencies
dotnet restore

# Build all projects
dotnet build

# Run tests (if available)
dotnet test

# Publish for production
# Windows
.\scripts\winpub.ps1

# Linux
./scripts/publish_linux.sh

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📁 Project Structure

flashback/
├── Flashback.Engine/          # Core print processing service
├── Flashback.Spooler/         # Port 9100 gateway (optional)
├── Flashback.Core/            # Shared libraries and utilities
├── Flashback.Config.Console/  # Terminal-based configuration
├── Flashback.Config.3270/     # TN3270 remote administration
├── Flashback.Config.WPF/      # Windows desktop GUI
├── Flashback.Config.WinUI/    # Modern Windows GUI
├── Flashback.Tray/            # Windows system tray controller
├── Flashback.TN3270Framework/ # TN3270 protocol implementation
├── Flashback.TestTool/        # Development testing utilities
├── scripts/                   # Build and deployment scripts
└── Working Documents/         # Technical documentation

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🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

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📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

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🙏 Acknowledgments

• Font Assets: Chain Printer, Dot Matrix, Line Printer, IBM Plex Mono, OCR-B (included for authentic vintage rendering)
• PDF Generation: PDFSharp
• TN3270 Framework: Custom implementation based on RFC standards VB.NET source code available.
• Community: Thanks to all vintage computing enthusiasts and contributors especially Mainframe Enthusiasts on Discord
• MPE Forever! on Discord for all the help with HP3000/MPE and testing when things were really rough!
• @Rudi (just because)
• @MarXtevens for exellent advice and patience
• @misterspock1 for testing when he probably shouldn't
• @Sgeo for being so patient working on overprinting and VM/370 issues.
• Cody for not killing me--or making me kill him.
• If I've missed recognizing you here, it's because I'm old. Forgive me.

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📞 Support

• Documentation: User Manual
• Issues: GitHub Issues
• Discussions: GitHub Discussions

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🗺️ Roadmap

• User-selectable font options for PDF generation
• Automatic printer detection on Windows networks
• Web-based configuration interface
• Additional host OS support (RT-11, etc.)

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Made with ❤️ for the vintage computing community

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