Designing Your RC2014 Compatible

This page outlines the options available in the RC2014 bus compatible, SC100 series of modules and backplanes.

The SC100 series includes products designed for both the standard RC2014 bus (40-pin) and the enhanced RC2014 bus (> 40-pin). All of the modules (except backplanes) that only use the 40-pin bus connector are in the low profile (25mm) format, while the enhanced bus modules are in the standard (50mm) format.

Standard bus (40-pin) modules work with enhanced bus (> 40-pin) backplanes and can be used along side enhanced bus modules. Most enhanced bus modules work with standard bus backplanes, although some will be function limited.


Obviously, the most important question is: “What colour should it be?”

SC100 series PCBs are offered in a range of colours as individual boards and as parts of kits. In addition, the design files are available for you to have your own boards manufactured in other colours.

Standard bus (40-pin) modules
Enhanced bus (> 40-pins) modules

This table shows products using the standard bus (40-pin).

Standard 40-pin bus

Backplanes

Blue

Green

Black

White

Red
SC133 – 11+1 slot, powerThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC141– 12+1 slotThis image has an empty alt attribute; its file name is tick-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC147 – 6+1 slot

Motherboards

Blue

Green

Black

White

Red
SC114 – Z80 board
SC130 – Z180 board

Power supply modules

Blue

Green

Black

White

Red
SC142 – 12-volt input
SC148 – 5-volt inputsoonThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Processor modules

Blue

Green

Black

White

Red
SC149 – Z80 CPUsoonsoon

Memory modules

Blue

Green

Black

White

Red
SC143 – Flash ROMThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC150 – Paged RAMsoonsoon
SC151 – Paged ROMsoonsoon

Storage modules

Blue

Green

Black

White

Red
SC145 – CompactFlash

Serial port modules

Blue

Green

Black

White

Red
SC139 – 68B50 ACIA

Digital I/O modules

Blue

Green

Black

White

Red
SC134 – 8 LEDs
SC135 – 8 outputsThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC136 – 8 inputsThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Prototyping modules

Blue

Green

Black

White

Red
see enhanced busThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Other modules

Blue

Green

Black

White

Red
SC137 – I2C bus master

This table shows products using the enhanced bus (> 40-pin).

Enhanced >40-pin bus

Backplanes

Blue

Green

Black

White

Red
SC112 – 6+1 slot, power
SC113 – 6+1 slot
SC116 – 3-slotThis image has an empty alt attribute; its file name is tick-small.jpgThis image has an empty alt attribute; its file name is tick-small.jpgsoonThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Motherboards

Blue

Green

Black

White

Red
TODO? – Z80 boardThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC126 – Z180 board

Power supply modules

Blue

Green

Black

White

Red
see standard busThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Processor modules

Blue

Green

Black

White

Red
SC108 – Z80 processor
SC153 – Z80 CPUsoonsoonThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg
SC111 – Z180 CPUsoonThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Memory modules

Blue

Green

Black

White

Red
SC152 – Z80 memorysoonsoon
SC119 – Z180 memorysoonThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Storage modules

Blue

Green

Black

White

Red
see standard busThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Serial port modules

Blue

Green

Black

White

Red
SC104 – Z80 SIO/2
SC110 – Z80 SIO/2 + CTC
SC132 – Z80 SIO/0This image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Digital I/O modules

Blue

Green

Black

White

Red
SC129 – 8 in, 8 out
SC103 – Z80 PIO

Prototyping modules

Blue

Green

Black

White

Red
SC115 – BreakoutThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpgThis image has an empty alt attribute; its file name is cross-small.jpg

Other modules

Blue

Green

Black

White

Red
SC102 – Z80 CTC timer

You can make your system with a mix of colours if you really want to stand out from the crowd or if you can’t make your mind up!

With the difficult colour decision out of the way, the next question is; “What do you want to do with your retro computer?”

Consider the following questions:

  • Do you want to just run existing software?
  • Do you want to write software?
  • Do you want to experiment with hardware?
  • Do you want your system in a neat box?
  • Will you be making changes to the hardware over time?
  • How authentic (retro) do you want your system?
  • Do you want to run CP/M?
  • Do you want to run RomWBW?

Do you need the enhanced bus?

Most systems do not need the enhanced bus. The enhanced bus includes some extra signals but these are only needed for a minority of applications. To provide the extra signals, at least some of the second row of bus pins are required.

Enhanced and Standard bus headers

The standard bus has the advantage of simplicity and less soldering. Also, the modules are easier to insert and remove. Notice how, using standard header pins, the Standard bus module (below, right) overhangs more than the Enhanced bus module (below, left) making it to easier to pull out of a bus socket.

Enhanced and Standard bus modules

What bits do you need?

An RC2014 bus compatible system is made up of either a motherboard and optional extra modules, or a backplane and a number of modules.

Motherboard plus modules
Backplane plus modules

A typical minimal system requires:

  • Backplane (to connect the modules)
  • Power supply
  • Reset circuit
  • A clock
  • A central processing unit (CPU)
  • Memory (RAM and ROM)
  • A serial port

These functions can all be provided on a single motherboard or they can be split in a variety of ways on a number of modules. Additional functions can be added by plugin modules.

Motherboards

Motherboards are essentially a single board computer (SBC) with bus sockets for expansion. All SC100 series motherboards have a horizontal bus connectors to allow modular backplane sections to be added.

Motherboards
Standard busSC114SC130
CPUZ80Z180
Clock (MHz)7.372818.432
ResetYesYes
SupervisorNoYes
Power in
via serial
Yes
5 volts
Yes
5 volts
Power in
connector
NoYes
5 volts
Power in
via module
OptionalOptional
RAM (kB)128512
ROM (kB)32512
FirmwareSCMRomWBW
Serial ports12
Baud rate9600300 to
115200
Status LEDs11
StorageNoneSD card
Storage
via module
Optional
CF card
Optional
CF card
OtherNoneNone
Vertical
bus sockets
31
Horizontal
bus socket
YesYes
Enhanced busSC126
CPUZ180
Clock (MHz)18.432
ResetYes
SupervisorYes
Power in
via serial
Yes
5 volts
Power in
connector
Yes
5 volts
Power in
via module
Optional
RAM (kB)512
ROM (kB)2 x 512
FirmwareSCM
RomWBW
Serial ports2
Baud rate300 to
115200
Status LEDs8
StorageSD card
Storage
via module
Optional
CF card
OtherI2C
SPI
RTC
Vertical
bus sockets
2
Horizontal
bus socket
Yes

Backplanes

Most SC100 series backplanes can be extended by joining backplane sections together. These backplanes have a number of vertical connectors for modules plus a horizontal connector for an additional backplane section.

SC147 – A 6+1 slot standard bus backplane

The horizontal connector can also accept a module, which makes it more accessible for experimenting and debugging hardware.

SC147 modular backplane (left) and SC126 motherboard (right)

Backplanes come in a range of different lengths, enabling small and large systems to be built.

Backplanes
Standard
Bus
SC133SC141SC147
Bus pins404040
Vertical
sockets
11126
Horiontal
socket
YesYesYes
Horzontal
plug
NoYesYes
Power
input
8-12 volt
1 amp
No
No
ResetYesNoNo
SupervisorNoNoNo
Module
spacing
0.6″
15.24mm
0.6″
15.24mm
0.6″
15.24mm
Enhanced
Bus
SC112SC113SC116
Bus pins808080
Vertical
sockets
663
Horizontal
socket
YesYesNo
Horizontal
plug
NoYesNo
Power
input
5 volt
1 amp
No
No
ResetYesNoNo
SupervisorNoNoNo
Module
spacing
0.6″
15.24mm
0.6″
15.24mm
0.6″
15.24mm

Power supply

There are several ways to power an SC100 series system:

  • From a USB to serial adapter. SC100 series serial ports have a 5-volt input pin which can be used to power the system. This works for modest size systems but isn’t ideal.
USB to serial adapter
  • From a backplane. Backplanes can include a power input connector. This is generally preferable to powering from a serial port.
SC133 – Modular backplane with 8-15-volt power input and a reset circuit
  • Another option is to power an SC100 series system from a power module. Power modules also provide a good quality clean reset signal and status indicator lights.
SC142 – Power supply module, with reset circuit and status lights

The first method of powering the system typically takes the power from a modern computer via a USB socket. The other two methods generally require a wall-mounted (wall-wart) power adapter.

Power modules
Standard busSC142SC148
Form factorLow profileLow profile
Voltage input8-12 volt5 volt
Max current1 amp1 amp
ResetYesYes
SupervisorYesYes
Status LEDs22
Enhanced bus
compatible
YesYes
Enhanced busn/a
Form factor
Voltage input
Max current
Reset
Supervisor
Status LEDs
Standard bus
compatible

Processor

The SC100 series offers a choice of two microprocessors:

  • The Z80 was extremely popular in the late 70s and 80s.
  • The Z180 was introduced later as advances in integrated circuit manufacture allowed more complex designs.

The Z180 is essentially software compatible with the Z80 but includes extra functions such as serial ports. The Z180 allows physically smaller systems to be created and also reduces the system cost.

Currently, to run RomWBW on an SC100 series system you require a Z180 processor.

If you want a system nearest to an authentic 1980 computer you should use the Z80 processor. If you are willing to use later technology then a Z180 based system will be a good choice.

Processor modules
Standard busSC149
CPUZ80
Clock (MHz)7.3728
ResetNo
SupervisorNo
RAM (kB)None
ROM (kB)None
Serial portsNone
Baud raten/a
FirmwareSCM
Enhanced bus
compatible
Yes
Enhanced busSC108SC111
CPUZ80Z180
Clock (MHz)7.372818.432
ResetYesYes
SupervisorYesYes
RAM (kB)128No
ROM (kB)32No
Serial portsNone2 x 115k
Baud rate
n/a
300 to
115200
FirmwareSCMNone
Standard bus
compatible
Some
limitations
No

Memory

Typical Z80 systems in 1980 had 64k bytes of RAM. It is possible to have more than 64k bytes of RAM on a Z80 system but it is easier to implement significantly larger memory maps with the Z180 processor.

Memory modules
Standard busSC143SC150SC151
RAM (kB)None128None
ROM (kB)4 x 128
FLASH
None4 x 128
FLASH
FirmwareSCMNoneSCM
For CPUZ80Z80Z80
Status LEDsNone11
Bus pins404040
Enhanced bus
compatible
YesYesYes
Enhanced busSC119SC152
RAM (kB)512128
ROM (kB)2 x 5124 x 32
FimrwareSCM
RomWBW
SCM
For CPUZ180Z80
Status LEDsNone2
Bus pins8050+
Standard bus
compatible
NoYes

Serial ports

Most systems include at least one serial port. This allows the retro computer to use a terminal, or modern computer acting as a terminal, as the main user interface.

Some processor modules and all motherboards include one or more serial ports:

  • SC111 has two serial ports. These have software-selectable baud rates. These ports are included in the Z180 CPU.
  • SC114 has one serial port. This is a very basic “bit-bang” port running at 9600 baud.

SC126 and SC130 both have two high-speed serial ports.

Serial ports can also be provided by dedicated cards:

  • SC110 has two serial ports (Z80 SIO) and a four-channel counter/timer (Z80 CTC). The second serial port has software-selectable baud rates controlled by one of the counter/timer channels.
  • SC132 has two serial ports typically fixed at 115200 baud.
  • SC139 has one serial port (68B50 ACIA) fixed at 115200 baud.
Serial modules
Standard busSC139
Ports1
Baud rate115200
Baud rate
control
None
Device
68B50
ACIA
ExtrasNone
Enhanced bus
compatible
Yes
Enhanced busSC104SC110SC132
Ports222
Baud rate
115200
300 to
230400
115200
Baud rate
control
Osc
Bus clk
Port B
via CTC
Osc
Bus clk
DeviceSIO/2SIO/2SIO/0
ExtrasNoneTimersNone
Standard bus
compatible
Some
limitations
Some
limitations
Some
limitations

Storage

If you want to load and save files you will need some form of storage. While it is possible to transfer data to and from a modern computer via a serial port, it is generally better to have some local storage on the retro computer. Two solutions are currently offered:

  • CompactFlash cards provide fast file access. SC145 allows CompactFlash cards to be used for CP/M and RomWBW.
SC145 with CompactFlash adapter

  • SD cards. The Z180 motherboards, SC126 and SC130, provide a port for connecting a MicroSD card adapter. This is supported by RomWBW.

SC130 with USB to serial adapter and MicroSD adapter
Storage modules
Standard busSC145
DeviceCompact
Flash
Enhanced bus
compatible
Yes
Enhanced busSC154
DeviceCompact
Flash
Standard bus
compatible
Yes

Digital I/O modules

Digital input/output modules can include signals to interface to external electronics and/or LEDs and switches. Input/output signals can either be fixed input or outputs, or they can be programmable bi-directional signals.

Digital I/O modules
Standard busSC134SC135SC136
Device
74 series
logic
74 series
logic
74 series
logic
Bi-directional
signals
NoneNoneNone
Signal outputsNone8None
Output LEDsYes (8)NoneNone
Signal inputsNoneNone8
Input LEDsNoneNoneNone
Enhanced bus
compatible
YesYesYes
Enhanced busSC103SC129
Device
Z80 PIO
74 series
logic
Bi-directional
signals
16None
Signal outputsNone8
Output LEDsNoneYes
Signal inputsNone8
Input LEDsNoneYes
Standard bus
compatible
YesYes

Prototyping modules

Prototyping modules
Standard busn/a
Features
Enhanced bus
compatible
Enhanced busSC115
Features
Breakout
Decoding
Standard bus
compatible
Some
limitations

Other modules

Other modules
Standard busSC137
FeaturesI2C bus
Enhanced bus
compatible
Yes
Enhanced busSC102
Device
Z80 CTC
(4 timers)
Standard bus
compatible
Some
limitations

Example systems

  • System #1: Minimal Z80 computer. Includes the Small Computer Monitor, BASIC, but no storage.
    • SC114 – Z80 motherboard with memory and 9600 baud serial port
  • System #2: Z80 computer with CP/M and CompactFlash file storage
    • SC114 – Z80 motherboard with memory and 9600 baud serial port
    • SC145 – CompactFlash interface module for file storage
    • A dedicated serial module is recommended but not essential:
      • SC139 – Single serial port (68B50 ACIA)
      • SC132 – Two serial ports (Z80 SIO)
      • SC110 – Two serial ports (Z80 SIO) plus timer (Z80 CTC)
  • System #3: Z80 computer with CP/M and CompactFlash file storage
    • SC112 – Backplane
    • SC108 – Z80 processor module (CPU, RAM, ROM)
    • SC145 – CompactFlash interface module for file storage
    • SC139 – Single serial port (68B50 ACIA)
      • Or perhaps a two-channel serial module:
        • SC132 – Two serial ports (Z80 SIO)
        • SC110 – Two serial ports (Z80 SIO) plus timer (Z80 CTC)
  • System #4: Z180 computer with RomWBW CP/M and SD card file storage
    • SC130 – Z180 motherboard
  • System #5: Z180 advanced computer with SD card for storage. Includes SCM and RomWBW CP/M.
  • System #6: Z180 computer with CP/M and CompactFlash file storage. Includes SCM and RomWBW CP/M.
    • SC112 – Backplane
    • SC111 – Z180 CPU module with 2 serial ports
    • SC119 – Z180 memory module
    • SC145 – CompactFlash interface module for file storage

Homebrew 8-bit retro computing