For several months now I’ve been working through how to reverse engineer the IF1 ULA. I’m pleased to say that the design work is now complete and the prototype works as expected. Early indications are that it performs slightly better than the original in reading cartridges (to be confirmed with further testing). The best I’ve managed so far is 122K off a real cartridge (there is a bit a a trick to this – the motor was at its slowest setting). Using the original IF1 I could only manage 114K with the same IF1 v2 rom, Microdrive and cartridge. On standard settings I consistently get about a 5% improvement but I’d be happy with the same as the original TBH.
The vLA-1 (as it will be called) will be a drop in service replacement for the 40-pin IF1 ULA. IF1 ULA functionality is replicated 100% including Shadow ROM switching, Microdrive, RS232 and NET functionality. The real item should be available in about 3 months after I’ve completed field testing, corrected any defects, and move to a limited production run.
Will keep you posted on further developments.