The Cromemco Single Card Computer (SCC) is a Z-80 (https://en.wikipedia.org/wiki/Zilog_Z80) computer on a single Printed Circuit Board (PCB.) In addition to the Z-80 (running at 4 MHz) it also includes a serial port, three parallel ports, five timers, 1 kilobyte of RAM and four IC sockets for up to either four 2708 1 KB, or four 2716 2 KB, EPROM chips. This was all placed on a single S-100 bus (https://en.wikipedia.org/wiki/S-100_bus) compatible PCB.
In the introduction of the SCC Instruction Manual (http://www.classiccmp.org/dunfield/s100c/crom/cromscc.pdf,) Cromemco says:
The Cormemco Single Card Computer (SCC) is a Z-80A based, S-100 bus microcomputer subsystem. The SCC is self-contained, excepting external power, making it an ideal choice for small to medium-scale dedicated applications. The SCC provides all the features one could want in a powerful, yet reasonably priced, single card microcomputer (see Figure 1)
The SCC was designed for control purposes, and in addition to a built-in monitor program, had a version of Dr. Li Chen Wang's Tiny BASIC, called 3K Control BASIC, available. The BASIC along with the monitor fit into two 2016, 2 KB EPROMs. This allowed simple programming of control tasks with easy access to modify memory and/or input/output (I/O) devices.
Cromemco also included this SCC as the default CPU in their 1980 Cromemco System Zero computer system. This control system included a 4-slot S-100 motherboard, a card cage, a power supply and a rack-mountable case.