Description
The RC2014 Orton 3C is a 3 chip computer that embodies the 1970s homebrew computer revolution. At its heart is a Z80 CPU clocked at 4HMz. 32k of SRAM is available to program, and a hex-inverter chip handles the clock circuit and front panel logic. It is capable of serial communication at 9600 baud. Programming is done by entering it one byte at a time via the switches on the front panel. The design of this computer is based on the late Karen Ortons Minimal Z80, and £5 for every kit sold will be donated to Cancer Research UK in her memory.
The computer itself comprises of two circuit boards. The first hosts the switches, LEDs, clock and logic circuits. The second hosts the Z80 and RAM and connects via an RC2014 expansion bus. The computer operates in two modes; Program and Run. In Program Mode the computer can be reset, the memory from address 0x0000 examined, and programmed from the switches. Once a program has been toggled in it can be set to Run mode where the contents of memory are executed.
Please don’t be fooled in to the simplicity of 3 chips making it a kit for the beginner’s. This really is for the hardcore enthusiast that can appreciate the genius of the design, has a grasp of Z80 code, and has the patience to toggle in a lot of bytes for something relatively trivial to happen.
Expansion Options
To broaden the audience and make things a bit more accessible, however, some enhancements are available. Firstly, due to the RC2014 bus between the two main PCBs, a backplane can be added. The RC2014 Backplane 5 is ideal, and will give 3 free slots of expandability.
With a backplane fitted, the Front Panel I/O Panel can be added. This will allow you to run simple programs that require basic input or output. Kill The Bit may not hold up well against modern titles like Doom or Call Of Duty, but it does at least allow for some gaming!
A laser cut, laser etched cherry veneered plywood front panel is available to house the Orton 3C and the Front Panel I/O Panel in the ubiquitous Blue Box. This is supplied unfinished, so will need either varnish, wax, oil or shellac, according to taste, for a more durable finish.
If you want to minimise the amount of toggling to be done, a 16k ROM module is also available. This ROM sits higher up in the Z80 address space and contains some simple handy routines that can be called. You will, of course, still need to toggle in a program in to RAM that calls these routines. But it will save you some flipping time.
There are some recommended bundles available, depending if you want just a pure RC2014 Orton 3C up to a machine with extra LEDs and switches and ROM, ready to go in to a Blue Box enclosure.
- Orton 3C – Just the 2 main PCBs, including 3 chips, switches, LEDs and passive components.
- Orton 3C + Backplane 5; As above, but including the Backplane 5 kit
- Orton 3C + PB5 + IO; As above, but including the Universal I/O Kit (with green LEDs)
- Orton 3C + BP5 + IO + Laser cut panel; As above, but including the cherry veneer panel to fit Blue Box enclosure
- Orton 3C + BP5 + ROM; Orton 3C kit, and the Backplane 5 kit and 16k ROM Module
- Orton 3C + BP 5 + ROM + IO; As above, but including Universal I/O kit (with green LEDs)
- Orton 3C + BP5 + ROM + IO; Laser cut panel – As above, but including the cherry veneer panel to fit Blue Box enclosure
