Until I get the time to write a detailed article on the Sinclair ZX80, here's a video I recorded about the system.
CPU: Z80 @ 3.25 MHz (usually an NEC µPD780C-1 equivalent).
Graphics: B&W, extremely limited. Shared system and gfx memory mean the bigger the program code, the less memory available for graphics.
Display blanks when code is running or a key is pressed... or anything else at all is happening.
Memory: RAM 1K (expandable to 16). ROM 4K (expandable to 8K).
Software Format: Tape.
Value: £90 - £300 (average). A boxed and sealed example was seen to sell for £1500, but this should not be considered an example of a normal transaction.