NOTE: This is a kit to assemble. You will need a solder iron, tin and possibly a multimeter.

This is a listing for the REV.C of the board and is currently on sale, while stocks last, to clear the inventory and make space for REV.D. If you are not sure wether you prefer a bargain on REV.C or splurge on a REV.D here is a list of what is new in REV.D:

• LEDs order swapped to have bit 0 on the right side
• Sliders wiring swapped for a more natural "right is on"
• Added LEDs for RTN,F0,FF flags so ALL MC14500 flags are now visible
• Added an I/O connector to allow connection of external loads/switches and sensors

The board is otherwise functionally identical and the programmer's model remains unchanged. So, if you are looking for a bargain and don't need the extra I/O or care about the LEDs order, buy with confidence this REV.C which has been on sale for over a year and enjoyed by over 170 customers with no complaints.

If you prefer the brand new REV.D check this listing: PLC14500-Nano REV.D

The PLC14500 Nano is a retro-style trainer board intended for the user to familiarize with the Motorola MC14500 1-bit ICU (Industrial Control Unit), PLCs and Ladder Logic. The board has abundant LEDs that show the status of the system buses and registers. This, combined with the possibility to run the software step by step, gives the user a great deal of insight into how their programs are executing. The slow clock mode makes instead for a mesmerizing light show that won't fail to impress when the board is parked on a desk, waiting for the next coding adventure.

Main features:

• 256 Bytes of program RAM (can be replaced with an EEPROM)
• 7 Inputs each with toggle and momentary switch capability
• 7 Outputs (LEDs)
• 1 Timer mapped to the I/O bus (0.5 to 11s, adjustable via a trimmer)
• 7 bits scratchpad RAM
• 3 clock modes (fast, slow, manual step)

True to its retro style PLC14500 Nano sports exclusively through-hole components and chips in DIP packages. You might notice an intruder in the Bill of Materials, an Arduino Nano! It's there purely to act as a bootloader, with a convenient USB interface that surely is easy to connect to modern PCs. However, to not spoil the illusion, the Arduino is mounted on the bottom side of the PCB, so it won't be visible when using the board.

The Arduino comes pre-loaded with 14500MON, an interactive assembler/monitor that will allow you to assemble and inspect programs as they are being executed by using just a serial terminal. (*1)

You also get a toolchain for Windows to assemble programs and upload them to the board over USB, both as a ready to run app (https://github.com/nicolacimmino/PLC-14500/releases) and the full source code.

The book

You can choose to complement your kit with the book "PLC14500 Programmers' Guide (1-Bit Programming in the 2020s)". The book guides you through the first steps to assemble and program the board, dives deep into the MC14500 instructions set and provides information and ideas on programming 1-Bit systems. Available in both hard cover and paperback versions, this 126 pages guide is the ideal companion for your PLC14500-Nano.

NOTE: You don't need the book to assemble and program the board, there is a lot of information freely available on my GitHub repo for that. Get the book if you want to dive deeper into the subject and if you appreciate some good technical read away from your screen.

What is included

• PLC14500-Nano PCB
• All components, including the Arduino pre-programmed with the PLC14500 bootloader and 14500MON
• Printed assembly instructions
• Printed full page assembly layout
• Printed BOM

*1) Kits shipped before April 2023 had only the regular bootloader flashed on the Arduino. If you have one of these, you can just head to https://github.com/nicolacimmino/PLC-14500/tree/master/14500mon and flash 14500MON on your board as well.