Programming a GAL22V10 for Z80: Vintage Computer Project

Table of Contents

1. Introduction
2. The Purpose of Collecting Vintage Computers
3. Building a Vintage Computer with CID CPU
4. Implementing Logic Functions with TTL Devices
5. Introduction to Programmable Devices
6. The Advantages of Programmable Devices
7. Programming Hardware for CPLD Devices
8. Real-Time Operating Systems and Microcontrollers
9. Using DOS for Programming Purposes
10. Troubleshooting and Fixing Hardware Issues
11. Editing Logic Functions and Design Files
12. Converting Chaddock Files for GAL Devices
13. Using Pal to GAL Software for Conversion
14. The Importance of Starting Windows
15. Initializing the Parallel Port
16. Loading and Programming the GAL Device
17. Verifying the Programmed Device
18. Conclusion

🔍 Introduction

Many people often wonder why someone would keep odd hardware stuff like vintage computers, such as a 486 running DOS, in the year 2019. They question the purpose of collecting these hardware computers and whether they actually serve any practical use. In this article, we will explore the world of vintage computers and their significance, as well as the process of building and programming a vintage computer with a CID CPU.

🖥️ The Purpose of Collecting Vintage Computers

Collecting vintage computers, especially those from the early days of computing, provides a glimpse into the history of technology and serves as a reminder of how far we have come. These hardware computers, like the 486 running DOS, carry a sense of nostalgia and allow enthusiasts to Revive the past by preserving and showcasing the technology of yesteryears. Additionally, they can serve as educational tools for studying the evolution of computer architecture and programming.

🛠️ Building a Vintage Computer with CID CPU

When building a vintage computer, one crucial component is the CID CPU (Centralized Integrated Device). The CID CPU is responsible for controlling memory chips and enabling the RAM and ROM as needed. Implementing this control requires glue logic, such as XOR gates, to handle the complex operations effectively. Traditionally, this was accomplished using separate TTL devices for each logic function, which presented challenges in terms of complexity and flexibility.

💡 Implementing Logic Functions with TTL Devices

To implement logic functions in a vintage computer design, one could utilize TTL devices. However, this approach comes with its own set of difficulties. Each logic function would require a separate TTL device, resulting in a complex and hard-to-maintain system. Furthermore, making changes to the logic functions would be tedious, as it would involve physically swapping devices. This laborious process highlights the need for a more versatile and efficient solution.

🌟 Introduction to Programmable Devices

Enter programmable devices, such as GAL (Generic Array Logic) and CPLD (Complex Programmable Logic Device). These devices offer the ability to program custom logic functions into them, providing a higher degree of flexibility compared to traditional TTL devices. GAL and CPLD devices are compatible with TTL and CMOS voltages, making them an ideal choice for vintage computer projects. These programmable devices act as the ancestors of modern FPGA (Field-Programmable Gate Array) devices.

✔️ The Advantages of Programmable Devices

The use of programmable devices like GAL and CPLD offers several advantages over traditional TTL devices. Firstly, they save space by consolidating multiple logic functions into a single device. This simplifies the overall design and reduces the number of components required. Additionally, changes to the logic functions can be made by reprogramming the device, eliminating the need for physical replacements. The flexibility and versatility of programmable devices make them a preferred choice for vintage computer enthusiasts.

🖥️ Programming Hardware for CPLD Devices

In order to program GAL and CPLD devices, dedicated programming hardware is required. One such example is the Skull Blaster, a programming hardware designed by a community member. This programmer connects to the computer via a standard parallel port data cable. The programming process is time-sensitive and requires a real-time operating system or a microcontroller for precise timing. DOS proves to be a suitable platform due to its ability to provide microseconds accuracy.

⏱️ Real-Time Operating Systems and Microcontrollers

When it comes to programming hardware devices like GAL and CPLD, real-time operating systems (RTOS) or microcontrollers play a crucial role. RTOS or microcontrollers are needed to achieve microsecond accuracy for precise timing during the programming process. Traditional operating systems, like Linux, lack the necessary real-time capabilities and multitasking abilities required for programming GAL and CPLD devices. DOS, being a real-time operating system, fills this gap and provides an optimal environment for the programming process.

💾 Using DOS for Programming Purposes

DOS, a real-time operating system known for its simplicity and precision, serves as an ideal platform for programming GAL and CPLD devices. With DOS running on a 486 machine, enthusiasts can utilize the precise timing capabilities required for programming vintage computer hardware. The DOS environment allows for accurate timing and control of the programming process, ensuring successful device programming without the complexities and limitations of modern operating systems.

🔧 Troubleshooting and Fixing Hardware Issues

When working with vintage computers and programming hardware, troubleshooting and fixing hardware issues may arise. These issues can range from bad contacts with the mainboard to faulty components. However, with proper troubleshooting techniques, enthusiasts can quickly address these problems and ensure smooth progress in their vintage computer projects. It is essential to be meticulous in identifying hardware issues and applying appropriate fixes to maintain the functionality of the systems.

📝 Editing Logic Functions and Design Files

To customize the logic functions of a vintage computer design, enthusiasts can modify the design files themselves. Opening the function file, usually in PDS format, allows for a comprehensive view of the logic functions to be implemented. By editing the function file, enthusiasts can specify the behavior of various components, such as enabling or disabling specific RAM or ROM chips based on the system's state. This customization empowers enthusiasts to tailor the vintage computer design according to their specific requirements.

🔄 Converting Chaddock Files for GAL Devices

When working with GAL devices, it is necessary to convert Chaddock files for compatibility. Chaddock files typically contain the logic functions and specifications of the desired vintage computer design. By using conversion tools like Pal to GAL software, enthusiasts can convert Chaddock files into GAL-compatible formats. This conversion step ensures that the logic functions are properly interpreted and programmed into GAL devices, enabling seamless integration within the vintage computer design.

🔄 Using Pal to GAL Software for Conversion

Pal to GAL software provides a convenient solution for converting Chaddock files into GAL-compatible formats. By selecting the appropriate conversion options in the software, enthusiasts can convert their Chaddock files into GAL 22V10 format. The resulting GAL file can then be utilized for programming GAL devices within the vintage computer design. Pal to GAL software simplifies the conversion process and eliminates compatibility issues, making it an essential tool for vintage computer enthusiasts.

🖥️ The Importance of Starting Windows

In certain scenarios, starting Windows plays a crucial role in the vintage computer programming process. Some specialized software and programming tools are designed specifically for the Windows environment. These tools may offer enhanced functionality or compatibility with modern hardware. Therefore, starting Windows becomes necessary to utilize these tools effectively and streamline the programming workflow.

🖥️ Initializing the Parallel Port

Before proceeding with programming GAL devices, it is essential to initialize the parallel port. Initializing the parallel port ensures proper communication between the programming hardware and the computer. This step is typically performed using dedicated software, such as the Aft Blast program Mentioned earlier. By initializing the parallel port, enthusiasts can establish a reliable connection and prepare the system for successful GAL device programming.

💽 Loading and Programming the GAL Device

Once the parallel port is initialized, enthusiasts can load the GAL file into the programming software. With the GAL file loaded, enthusiasts can select the desired GAL device from the available options. After ensuring that the programming hardware is properly connected to the GAL device, the programming process can commence. This entails writing the logic functions into the GAL device, effectively programming it with the custom design.

✅ Verifying the Programmed Device

After programming the GAL device, it is crucial to verify its correctness and functionality. Verification ensures that the programmed logic functions are correctly implemented and behave as intended. By utilizing the programming software's verification feature, enthusiasts can validate the GAL device and ensure that it operates according to the design specifications. This step adds an extra layer of confidence and quality control to the vintage computer build.

🏁 Conclusion

Building a vintage computer with a CID CPU and implementing logic functions using programmable devices opens up a world of possibilities for enthusiasts. The process involves collecting vintage computer hardware, utilizing programmable devices like GAL and CPLD, and programming the logic functions with precision using a real-time operating system like DOS. By embracing the nostalgia and functionalities of vintage computers, enthusiasts can embark on exciting projects that combine the classic with the contemporary, bridging the gap between the past and the Present.