program memory and 640 bytes of RAM. Only 75 µs is required to read 128 digital input pins and to write to 128 output pins. 16 rotary encoders are handled within 100 µs. Analog inputs are scanned in the background every 200 µs; changes larger than a definable minimum range trigger a user hook. Up to 256 MIDI events can trigger dedicated functions; processing of the event list requires about 300 µS. MIDI events can also be processed by a user routine for sysex parsing or similar jobs. A user timer is available for time triggered code. Support for other high-level languages apart from C is possible. MIOS hardware The MIOS hardware is organized around the concept of MIDIBox Hardware Platform (MBHP). The MBHP are highly versatile motherboards, offering the highest possible number of connections for a given processor. Four versions of MBHP are currently available: MBHP for PIC16F877 and PIC18F452 (8 bits processors). The two chips are pin compatible, but the PCB needs a simple change between the two chips MBHP for LPC1769 (32 bits ARM7 processor) MBHP for STM32F407 (32 bits Cortex M4 processor) When a project needs less I/O than the ones available on a given MBHP, the MIDIBox concept allows to create a simplified PCB dedicated to this project. This is the approach used on Sammich MIDIBox SID and Sammich MIDIBox FM. These two kits contain the original MBHP design, but with a simplified PCB, dedicated to the connection with a SID chip or a YMF262 chip. In the case of the STM32F407 MBHP, the CPU is mounted on a module used as a daughterboard, made by ST and sold as a development board (called STM32F4 Discovery by ST). The final user does not have to deal with SMD components, the daughterboard being mounted on standard 0.1" connectors Complete solutions At this point there are 11 fully documented projects available, as well as a large number of user projects generated by the community. The official projects are as follows: MIDIbox SEQ V3: 16 Track Live Step and Morph Sequencer + advanced Arpeggiator MIDIbox SID V1: Hardware MIDI-controllable Synthesizer based on the MOS Technology SID (MOS6581) sound chip as shipped with the Commodore 64/128 MIDIbox FM V1: Hardware synthesizer based on the Yamaha YMF262 sound chip (also known as OPL3) for generating the famous FM sounds known from Soundblaster (compatible) soundcards of the early 90s MIDI Merger