The vLA81 is a modern plugin replacement for the Sinclair ZX81 ULA. 


As they simply don't make ZX81 ULAs anymore, then unfortunately if the ULA has failed (and there's not much else on a ZX81 to fail), then options for repair are rapidly diminishing. The vLA81 provides a simple way to keep these icons of 80's computing going.

Apart from providing the functionality of both the earlier 2C158E/184 ULA (without back porch) and the 2C210E (with back porch), the vLA81 also has a few extras added.

vLA81 features:

  • Fits within the same 40 pin DIL socket outline as the original ULA.
  • Narrow IC pins for easy plugin ULA replacement. In most cases the existing socket will be OK (unless, of course, the existing ULA is soldered in).
  • Provides the same functionality as the 2C210E Sinclair ULA.
  • Video level selectable between standard video (suitable for direct connection to a 75 ohm monitor input) and high sync level (suitable for the modulator input or some video mod boards).
  • Back porch on/off select.
  • Internal 32K memory support (High or Low for the different hires schemes).
  • Programmable user configuration gives access to:
    • Inverse or normal video and choice of black or white border.
    • 50/60 Hz video standard.
    • Ability to map ram to the ROM space (write protect enable/disable – 32K internal ram required).
  • Tested with an extensive suite of ZX81 software.
  • Ideal for preserving the original ZX81 ULA.
  • Low power consumption.


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