Your DivMMC can save as well as load. Here’s how to write a ZX Spectrum program to a .tap file with ESXDOS TAPE OUT and load it back from the NMI menu.
A box of free Spectrum gear from Sam Gidman of The Lost Level: a boxed Spectrum+, a cassette deck, a Kempston interface and a Competition Pro joystick.
A Spectrum 48K+ from my to-fix pile turned out to have a rare AMI SAGA-1A ULA. I test it, check the picture and measure how cool it runs against a Ferranti ULA.
A completely free 1980s Amstrad CPC 464 system, donated by Matthew Hicken and posted by Ross Taylor Green, with a CTM644 colour monitor and a big box of tapes.
A live test of the Commodore 64, joysticks, power supply and Datassette that arrived in an Amiga A600 box, loading IK+ from tape to see if it all works.