Projects

Like many other hobbyist we have always been fascinated by radioactivity and the sensors to detect it. Geiger-Müller tubes are a common and relatively inexpensive way to measure radiation. GRAD is a complete solution for radiation counting in an Arduino shield form factor. Its main features are dual tube support to increase sensitivity and very low power consumption.

Arduino shields are ubiquitous and provide a wide range of sensors and interfaces. Commodorino allows their use on a Commodore 64. The interface provides good compatibility with the Arduino Uno platform. Digital I/O, Analog In, SPI, I2C and limited interrupt and Serial port are implemented and additional Micro SD card socket is available for future expansion.

The geoRAM is a 512KB memory expansion for the Commodore 64 and 128 designed by Berkeley Softworks for use with GEOS. While not as fast as the Commodore REU due to its lack of DMA capabilities, it still provides a significant performance boost. GRAM/4D is a 4MB geoRAM compatible cartridge based on a two 4Mx4 DRAM devices.

The apple IIgs is the most advanced computer in the Apple II series. Equipped with a 65c816 8/16-bit CPU with 24-bit address space it could address up to 16MB of memory. The original rom 01 model shipped with 256KB of fast RAM, the revised rom 3 shipped with 1MB (both had an additional 128KB of standard RAM and 64KB of sound RAM). RAMGS/4 is a newly designed 4MB memory expansion card for this great classic computer.

The 80 column output of the Commodore 128 is the same digital RGBI used by the original IBM CGA graphics adapter. Unfortunately nowadays is quite difficult to find a monitor with the suitable RGBI input. The CGA2RGBv2 adapter will convert the TTL RGBI to analog RGB suitable to be connected directly to a 15KHz capable RGB monitor or to the popular Gonbes GBS-8200 VGA converter.

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.

Schematics

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.