Zeal 8-Bit Computer (Z80 based)

The Zeal 8-bit Computer is a modern, minimalistic, hobbyist computer built around the classic Z80 microprocessor. The Z80, first introduced in 1976 by Zilog, was one of the most popular 8-bit CPUs used in early home computers and embedded systems. The Zeal 8-bit Computer typically re-implements the Z80 architecture, offering a hands-on learning experience for enthusiasts interested in low-level programming, retro computing, or hardware design.

Specifications

1. Central Processing Unit (CPU)

• Model: Zilog Z80
• Architecture: 8-bit
• Clock Speed: 2 MHz to 20 MHz (typically 4 MHz or 8 MHz)
• Address Bus: 16-bit (capable of addressing 64 KB memory)
• Data Bus: 8-bit

2. Memory

• RAM: 16 KB, 32 KB, or 64 KB (configurable based on the build)
• ROM/EEPROM: 8 KB to 32 KB (usually containing a monitor program or bootloader)
  • Often preloaded with a simple operating system or program loader (like CP/M or BASIC interpreter)

3. Input/Output (I/O)

• GPIO Pins: Available for interfacing with external hardware (number and type vary by build)
• Serial Communication: RS-232 or USB-to-serial for interfacing with other devices
  • Can be used for programming, loading software, and communication with a PC
• Peripheral Support: Memory-mapped I/O for peripherals such as:
  • Keyboards
  • Displays (LCD, VGA, or other simple video output)
  • Storage devices (SD card reader, or parallel storage)
• Bus Interface: Expansion headers for additional I/O components or custom circuits

4. Display and Input

• Display: Optional, usually text-based using:
  • Small LCD screen
  • VGA/Composite output for retro-style display (optional)
• Input: Typically includes:
  • Keypad or Keyboard for input
  • Optionally, serial input via a terminal

5. Power Supply

• Power Source: 5V DC or 3.3V DC, depending on the design
• Current Requirements: Typically under 500 mA, depending on peripherals

6. Operating System

• Monitor Program: Simple ROM-based monitor for basic interaction (loading programs, running code)
• Supported OS:
  • CP/M (Control Program for Microcomputers): Classic OS for Z80 systems
  • BASIC Interpreter: For easy programming directly on the machine
  • Custom minimal operating systems or bootloaders

7. Storage

• External Storage:
  • SD card interface (used to load programs or store data)
  • Other parallel storage options depend on the build
• Boot Method: Programs loaded from ROM, serial interface, or external storage like SD cards

8. Expandability

• Expansion Ports: Bus interface allowing additional memory, I/O, or custom circuit boards
• PMOD-style connectors: Commonly used to connect peripherals or other accessories
• User-Designed Modules: GPIO pins allow for custom add-ons and peripherals

9. Programming

• Programming Language:
  • Assembly (Z80): The primary low-level language used for programming
  • High-level language options include BASIC, C, or other retro programming languages
• Development Tools:
  • Cross-compilers (such as z88dk) for modern PC-based development
  • Assembler/debugger for on-board programming

10. Physical Characteristics

• Form Factor:
  • Custom-built, often a small PCB or breadboard setup
  • Case options vary; many are DIY enclosures
• Dimensions: Varies depending on the specific build; typically compact for retro or DIY setups

11. Additional Features

• Audio Output: Optional speaker or buzzer
• LED Indicators: For power, data transfer, or other system statuses
• Timers/Interrupts: Built-in Z80 timers and interrupt handling for system events