Latest prototype


November 2022: First release of Zeal 8-bit computer, the board keeps its size of 15x10cm and all its features. It adds more stability to the RESET signal, generated on power up and when the reset button is pressed, thanks to a dedicated voltage supervisory circuit. Moreover, jumpers have been added in order to enable or disable the V-Blank and H-Blank signal coming from the VideoCard Connector. This will prevent providing any voltage to the external video card. Indeed, in practice, this protects the Zeal 8-bit Video Card, which relies on an FPGA, to receive any 5V signal on these pins/IOs.

In terms of features, everything remains almost the same as the previous prototype. The signals BUSREQ and BUSACK from the Z80 processor are now accessible near the VideoCard Connector thanks to two new pins on the PCB. This simplifies the support of DMA for external video cards. The extension port has been changed for a 50-pin one as more signals are available on it. This port is backward compatible with the former 40-pin one.

Here is the full list of features:

  • Z80 CPU in PLCC package (w/ socket)
  • Z80 PIO in PLCC package (w/ socket)
  • MMU offering a 22-bit (4MB) physical address space, and 4x16KB virtual address space
  • 256KB of NOR flash. The flash is in PLCC package (w/ socket)
  • 512KB of RAM
  • Programmable Logic Device for logic decoding/mapping (GAL16V8B)
  • I2C RTC w/ 2032 battery socket
  • Voltage supervisory circuit
  • Fuse w/ socket
  • 10MHz DIP oscillator
  • USB-C for power input
  • PS/2 Keyboard connector
  • 50-pin extension port
  • 16-pin user port for accessing internal buses (UART & I2C) and PIO port A
  • 40-in video card connector