Great work - nice to see how the "Arduino" side of BlackIce can be used with low cost hardware to produce a user interface - though I don't look forward to debugging EDSAC machine language in Hex!
What should be appreciated here is your integration of the ICE40 FPGA and the STM32L433 ARM processor - communicating over the SPI bus - such that the ARM can provide user interface support to the FPGA - written in Arduino code, which opens it up to a wider audience.
From this point - with the inclusion of the Adafruit GFX graphics library - projects such as logic analysers, storage oscilloscopes and other "visual" display instruments just got a whole lot easier.
Utilising the 5Msps 12bit ADC on the STM32 means that digital multimeters, FFT analysers and other bench equipment could be created.
Thanks for sharing - please put up a GitHub link to your repository when you get a chance.