Provides the same functionality as the 6C001-7 Sinclair ULA.Ĥ. A low profile and 40 pin DIL footprint means that the vLA82 is designed to fit in a ‘rubber key’ ZX Spectrum case without further modifications.ģ. In most cases the existing socket will be OK.Ģ. Ideal for preserving the original ZX81 ULA.ġ1. Tested with an extensive suite of ZX81 software (full list to follow).ġ0. Configuration port socket provided on PCB base for external config switch option.ĩ. Ability to map ram to the ROM space (write protect enable/disable – 32K internal ram required).Ĩ.Inverse or normal video and choice of black or white border.Programmable user configuration gives access to: Internal 32K memory support (High or Low for the different hires schemes).ħ. 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).Ħ. Provides the same functionality as the 2C210E Sinclair ULA.Ĥ. In most cases the existing socket will be OK.ģ. Narrow IC pins for easy plugin ULA replacement. Fits within the same 40 pin DIL socket outline as the original ULA.Ģ. As the Xilinx XC9572XL CPLD used in the vLA81 had unused resources I decided to add some extra functionality (see features below).ġ. Over the time the other vLAs were progressing the vLA81 underwent its own evolution. In parallel with the design, schematics were refined, PCBs finalised, and samples sent out for testing when they became available.Ī working vLA128 was completed in May 2019. A working vLA82 prototype was completed in March 2019 and work was begun on the vLA128.

Armed with Grant Searle’s fantastic ZX80/81 repository and Chris Smith’s wonderful expose of the Spectrum ULA, I started about a year ago on the vLA81.Ī functioning vLA81 was completed in October 2018 and work started on the vLA82, by far the most complex of the three. I knew that all of these had been already done before but as the inner workings had not been published in detail this meant that there would be plenty of design still required (the part I enjoy the most). VLA81/82/128 now all available on SellMyRetro….Īfter the vLA1 was completed I set myself a challenge to replicate the functionality of some of the other Sinclair ULAs, firstly the ZX81 followed by the ZX Spectrum and finishing with the Toastrack ULA (as this would leverage most of the ZX Spectrum ULA design).

Download zx81 emulator