Modular RCBus system (SC700 series)

The SC700 is a modular 8-bit computer built around the RCBus. The system conforms to the RCBus specification.



The design is open source with full details of the schematics, printed circuit board Gerber files, and software, either on this website or linked from this site. Kits are available for those who would like the convenience and reassurance that kits offer.

Software and firmware support includes RomWBW and CP/M.

The following modules are available.

The RCBus is an extended version of the RC2014TM bus. The illustration below attempts to show how the different retro-computer designs on this website relate to each other.

I/O Device Addresses

The limited I/O address space is currently assigned as follows:

I/O AddressUse
0x00 to 0x03Digital I/O
0x08 to 0x0BStatus LED (active low)
0x0CI2C bus master
0x10 to 0x17Compact Flash #1
0x18 to 0x1BReserved
0x20 to 0x23Bit-bang serial RTS, or
ROM bank select A15
0x28 to 0x2BBit-bang serial TXD, or
ROM bank select A16
0x30 to 0x33RAM bank select A16
0x38 to 0x3BRAM/ROM select (128k Z80 systems)
0x38 to 0x3FDiagnostic LED port (512k Z80 systems)
0x40 to 0x41Serial ACIA #2
0x80 to 0x81Serial ACIA #1
0x80 to 0x83Z80 SIO #1
0x84 to 0x87Z80 SIO #2
0x88 to 0x8BZ80 CTC #1
0x8C to 0x8FZ80 CTC #2
0xC0 to 0xFFZ180 CPU internal registers


  • This product is designed for hobby use and is not suitable for industrial, commercial, or safety-critical applications.
  • The product contains small parts and is not suitable for young children.

Homebrew 8-bit retro computing