The Spectrum’s most infamous limitation is "attribute clash" (color conflict within an 8x8 pixel cell). Modern critics call it a bug. From a 1982 ULA design perspective, it was the only viable option.
To save RAM (and gates on the ULA), the Spectrum famously splits color from pixels.
Modern approach: Write this in VHDL/Verilog for a CPLD or use an RP2040 with PIO state machines.
Projects like the ZX Spectrum Next or ZX Fusion use Field-Programmable Gate Arrays to recreate the ULA’s logic with cycle-perfect accuracy. These allow for modern luxuries like HDMI output and SD card storage while running original Sinclair BASIC code.
The Spectrum’s most infamous limitation is "attribute clash" (color conflict within an 8x8 pixel cell). Modern critics call it a bug. From a 1982 ULA design perspective, it was the only viable option.
To save RAM (and gates on the ULA), the Spectrum famously splits color from pixels.
Modern approach: Write this in VHDL/Verilog for a CPLD or use an RP2040 with PIO state machines.
Projects like the ZX Spectrum Next or ZX Fusion use Field-Programmable Gate Arrays to recreate the ULA’s logic with cycle-perfect accuracy. These allow for modern luxuries like HDMI output and SD card storage while running original Sinclair BASIC code.