What is RC2014?

RC2014 is a simple 8 bit Z80 based modular computer. It is inspired by the home built computers of the late 70s and computer revolution of the early 80s. It is not a clone of anything specific, but there are suggestions of the ZX81, UK101, S100, Superboard II and Apple I in here. It nominally has 8K ROM, 32K RAM, runs at 7.3728MHz and communicates over serial at 115,200 baud. As a bare minimum, you will need a CPU, ROM, RAM, Clock and Input/Output module. The RC2014 is designed in such a way that you can build your own modules to expand it. As such, if you have access to similar components, or have specific needs, you might not need all the items I have on offer.

What is this module?

This is the serial module which is supplied with the RC2014 Pro or RC2014 Zed, although with an updated ROM, it can also be used as a replacement for the serial module supplied with the RC2014 Classic ][, or if you are building your own custom RC2014 variant. It can be used with Standard Bus backplanes (Backplane 5 or Backplane 8) with single row header pins, or with Enhanced Bus backplanes (Backplane Pro) with double row header pins. If the Standard Bus option is chosen, then a 20 pin straight header is also supplied in case you need access to the CLK2, TX2 and RX2 signals.

This is a dual port serial module based on the Zilog SIO/2 chip. It features 2 UART, Port A and Port B, thus allowing your RC2014 to connect to 2 separate devices, for example, a terminal and a printer.

The speed of Port A is derived from the main clock running the CPU (ie 7.3728Mhz on a standard RC2014) which gives a baud rate of 115200bps.

Port B can be clocked from the same clock via a jumper, which will also result in it running at 115200bps. Alternatively, it can get it's clock from the Clock2 pin on the enhanced bus. If using the Dual Clock Module then standard serial speeds down to 4800bps can be used.

Jumpers on both Port A and B allow the RC2014 to be powered from an FTDI cable.

The Z80 ports that this module connects to are different to those used by Grant Searle and Dr Scott Baker, and operate differently to the MC68B50 ACIA supplied with the standard RC2014 Serial I/O Module. The version of Microsoft BASIC or CP/M supplied previously will not work with this module. If you have the ability to burn EPROMS, then you can download SIO/2 versions of BASIC and CP/M from the RC2014 Github site or you can purchase a pre-programmed ROM and/or compact flash with this module.

If you have written your own operating system to run on RC2014, or adapted existing software, then you will need to update it to use the following ports;

• SIOA_D .EQU $81
• SIOA_C .EQU $80
• SIOB_D .EQU $83
• SIOB_C .EQU $82

What do I get?

• PCB Only Just the bare PCB
• Full Kit The PCB, chips, sockets, headers, resistors and jumpers
• Additional Media Optional items include a 128mb or 64mb Compact Flash with CP/M installed, and a 27C512 PROM with 32k BASIC, 56k BASIC and CP/M console (24886009) pre-programmed for SIO/2

Important note The SIO/2 supplied is the Zilog Z84C4206PEG which is rated for a clock speed of 6Mhz. This means that a RC2014 running at 7.3728Mhz is overclocking it. I have had one running for many hours, including a constant demo for 7.5 hours at a show, where it sent out approx 408600 characters without issue. Therefore, I believe this part is up to the job, however, if you are running mission critical life or death applications on your RC2014 you should be certified and will need to conduct your own tests.

RC2014 is a trademark of RFC2795 Ltd.