<u have a GRiD Compass with bubble memory, you get an OS <that acts like it's in ROM, but bubbles are writable. Lessee here. My supercrate s100 has CPM/BIOS/Monitor in rom. takes about 3sec to selfcheck and boot. I have an s100 crate with a 2mb write once romdisk of my design. I also have a z80 system with an two intel BPK72 bubble memories on. Each one give 128kb of space. All easily predate the GRID. Allison