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.