SC133 is a modular backplane designed for the RC2014 bus.
Power input
The backplane has been designed to be powered from a D.C. supply between 8 and 15 volts, and may draw up to 1 ampere.
Power can be connected via a 2.1 mm power jack (J1), or via screw terminals (J2), or via header pins (P2). The power jack must be wired for centre positive.
The input power can be switched on and off with the toggle switch (SW1). The switched supply is then fed to the 7805 regulator which reduces the input voltage to 5 volts. The power LED (LED1) indicates the presence of the 5 volt supply.
The regulated 5 volt power can be taken from the backplane via screw terminals (J3) or header pins (P3) to power external circuitry.
The illustration (right) shows the power connectors on the backplane.
The red “+” and “-” indicate points where an 8 to 15 volt supply can be connected to power the system.
The green “+” and “-” indicate points where a 5 volt output is available to power other devices. This is the voltage regulated by the 7805 (U1) and switched on and off by the toggle switch (SW1).
Reset
The backplane includes two reset buttons, one facing straight up and the other facing forwards. These buttons both pull the reset signal low. An external reset button can be connected via header pins (P1), if required. The reset signal can also be pulled low by switches or circuitry on any connected module.
Module sockets
The backplane has 11 vertical and 1 horizontal RC2014 bus compatible 40-pin module sockets. RC2014 bus compatible modules can be connected to any of these sockets.
It should be noted that modules designed for the enhanced RC2014 bus, which has a partial second row of pins, may not work with 40-pin bus sockets, or may work with limitations. Similarly, modules designed for extended RC2014 style bus systems, such as the 80-pin bus, may not work.
The horizontal bus socket allows a module to be connected horizontally which can make access easier during development or debugging. In addition this socket allows the backplane to be extended by connecting additional modular backplane sections, such as SC113.
Option links
It may be desirable to isolate some signals on the backplane. This might be necessary if you have, for example, two serial modules, each linked to its own terminal module. This set up would require the signals between the first serial module and its terminal module, to be isolated from the signals between the second pair of modules.
To isolate a signal from one or more module sockets, cut the thin track on the bottom of the board.
These are the isolation links as seen on the bottom of the printed circuit board:
| Short row | Long row |
| TX | |
| RX | |
| User 1 | User 1 |
| User 2 | User 2 |
| User 3 | User 3 |
| User 4 | User 4 |
Small Computer Central 