PicoBSD was a single-floppy disk

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

 version of FreeBSD

FreeBSD

FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...

, one of the BSD

Berkeley Software Distribution

Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 descendants. In its different variations, PicoBSD allows one to have secure dialup access, a small diskless router, or even a dial-in server, all on only one standard 1.44MB floppy. It runs on a minimum 386SX CPU

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 with 8MB of RAM (no hard disk

Hard disk

A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

 required).

PicoBSD is freely available under the BSD license. The main developer was Andrzej Bialecki, and the latest version is 0.42. Dinesh Nair had then backported the PicoBSD build scripts to FreeBSD 2.2.5, allowing the addition of a few more binaries in the dialup flavour due to FreeBSD 2.2.5's smaller binary executable format.

With flexibility that FreeBSD gives, along with the full source code

Source code

In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

 being available, one can build a small installation performing various tasks, including (but not limited to):

• Diskless workstation
  Diskless workstation
  A diskless node is a workstation or personal computer without disk drives, which employs network booting to load its operating system from a server...
  
  
• Portable dial-up access solution
• Custom demo-disk
• Embedded controller (flash
  Flash memory
  Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
  
   or EEPROM
  EEPROM
  EEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration...
  
  )
• Firewall
• Communication server
• Replacement for commercial router
• Diskless home automation
  Home automation
  Home automation is the residential extension of "building automation". It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC , appliances, and other systems, to provide improved convenience, comfort, energy efficiency and...
  
   system
• And many others

In FreeBSD 5, it has been superseded by the NanoBSD framework.

Further reading

• PicoBSD is now included in the FreeBSD source files where it is used by embedded system developers to create their own system images. It can be used with recent versions of FreeBSD and it is located in /usr/src/release/picobsd/ .