The PCPI Appli-Card was the first single board computer style CP/M card for the apple II. It featured a 6MHz Z-80 CPU paired with 64KB of RAM and 2KB of ROM. Thanks to the high clock and zero wait states DRAM accesses the card performed almost 3 times as fast as the Microsoft SoftCard. The GZ/80-B00 is a new implementation of the PCPI card with a 20MHz Z-80 CPU and 512KB of static RAM.
RS232 are still very popular to control legacy equipment. In industrial settings with long cable runs, interference and different ground references it is necessary to have galvanic isolation. ISO232 is a simple implementation using the FTDI FT230X and opto isolators that can reach speeds up to 115200baud.
The schematics is divided in four main portions.
A good random numbers generator is fundamental to ensure the security of many modern data encryption algorithms. Depending on the workload, the entropy collected automatically by the kernel might not be sufficient to generate the random numbers at the requested rate. In these cases an external entropy source can greatly improve performance. GRAND is a USB TRNG (True Random Number Generator) based on the ST Microelectronics STM32.
The Microsoft Softcard was the first card to allow CP/M software to run on the Apple II. It was originally developed to simplify the porting of Microsoft Basic to the Apple II. It turned out to be a great success and at some point in time it was the most popular CP/M platform in use.
This success prompted the development of many compatible cards. Some exact copies, some enhanced or cost reduced. The GZ/80 is a modern implementation of a Softcard compatible card with an additional turbo mode with approximately double the speed of the original card.
Many MCU applications are portable and need a mean to provide power on the go. There are many solution based on Li-ION and Li-Polymer batteries. However Lithium chemistries need sophisticated charging and protection circuits to avoid dangerous situations. For lower power projects NiMH batteries provide a simpler and safer alternative. NUPS (NiMH UPS) can provide 3.3V and 5V using 1 to 3 AA or AAA NiMH cells.
While working in the lab it's often useful to have a small isolated power supply handy. Depending on the circuit configuration, ISO01 can generate galvanically isolated unipolar and symmetric voltages from a single 3.3V or 5V rail. The circuit is based on the Texas Instruments SN6501 transformer driver and uses an easy to obtain off the shelf transformer.
Active termination is required to get newer high performance drives working on vintage computers. Unfortunately both the Amiga and older Apple computers use a DB25 SCSI connector which makes finding a suitable terminator quite difficult. GTERM25 solves this problem providing a high performance active terminator with a DB25 connector and SCSI diagnostic LEDs.
Many MCU applications use electro-mechanical relays to control AC loads. While this is an excellent solution for occasionally turning on/off a load, it is not suited for frequent switching or PWM applications. SSR1/A is an opto-coupled solid state relay that can control two AC loads in a arduino shield form factor.
The NVIDIA Jetson Nano is a great device and its choice of I/O is ideal for user space development. If you are a kernel hacker, however, you will soon feel the need for serial console and a reset button. If you want to hack the bootloader you will also need a recovery button. The Nanobug integrates a UART to USB and buttons into a little board that plugs directly into the nano developer kit.