pico6502 works. An RP2350 in the 6502 socket, running Galaxians and Chess on a BBC Model B and BASIC on an Apple 1 Replica. The PIO timing bug that was stalling execution is fixed and the bus cycles are clean. Next: custom BBC drivers for the FDC, hard disk, Econet and sideways RAM/ROM. What it is: a drop-in CPU replacement built on the picoZ80 framework, so it brings the same ICE debug shell with it — you can halt the machine, inspect memory and single-step from a serial console while the host is running. What was wrong: the 6502 has tighter bus timing than the Z80, and the PIO state machines driving PHI2, R/W and the data bus were a few nanoseconds out of phase with the host. Reads worked, execution didn't. The fourth image is the LA5016 capture that finally showed it, with PHI0/PHI1/PHI2, SYNC, R/W and the bus lines side by side. What's next: the BBC side gets interesting once the CPU is trustworthy. Because the RP2350 sits between the software and the hardware it can present peripherals the machine never had, so the plan is virtual drivers for the 8271/1770 FDC, a hard disk, Econet and sideways RAM/ROM, then on to the Master 128 with its 65C12. Project: eaw.app/pico6502 #pico6502 #retrocomputing #6502 #BBCMicro #Apple1 #RP2350