The current configurations on my Osborne 1s are:

• 4MHz Zilog Z80B microprocessor
• 64k ram

  Single Density with beige case:

  • 2-95k (single density) 5.25" floppy drives
  • 51x24 text 5" monochrome monitor

  Double Density with light blue case:

  • 2-190k (double density) 5.25" floppy drives
  • 104x24 text 5" monochrome monitor
  • Internal 300 baud modem

The Osborne 1 is widely considered to be the first "portable" computer (it weighs 20 pounds). They were designed to use the CP/M 2.2 operating system. The Osborne 1 shipped with an RS-232c serial port (standard female DB-25), a modem port (a stripped down serial port specifically for use with Osborne's internal modem, this is a male DB-9, and I know not if the pinouts are the same as on the current DB-9 serial ports), and an IEEE-488 (HP-IB) I/O port which with the right cable could be used as a standard parallel port (this used a non-standard male header rather than the standard IEEE-488 conector). In order to maximize usable memory, screen memory was paged out, and was normally only accessed through the BIOS. For the serious user a powered port for the connection of an external monitor, and a place to connect an external battery are provided. The monitor port is very non-standard as it directly provides the signals which go to a CRT rather than nicely packaging this information.