Commodore CBM-II B256

The Commodore CBM-II B256 belonged to Commodore’s ambitious CBM-II family, using a 6509 processor and banked memory in a modern low-profile enclosure.

Limited production and an abrupt market withdrawal made CBM-II systems rare despite their advanced design.

Notable Features

• The 256KB configuration distinguishes this model.
• Banked memory allowed the 6509 to address more than 64KB.

Historical Significance

• Limited production and an abrupt market withdrawal made CBM-II systems rare despite their advanced design.

Collector’s Notes

• Board revision, regional video standard, power supply, keyboard legends and original accessories should be recorded.
• Memory, storage, displays and expansion hardware should be documented because configurations often changed during a system’s working life.

Specifications

Technical Information
Name	Commodore CBM-II B256
Manufacturer	Commodore
Launched	Saturday, January 1, 1983
Discontinued	1984
Country	United States
CPU	MOS 6509 at 2 MHz
Units Sold
Form Factor	Professional keyboard computer
Power	External or internal mains supply according to model
Networking	Commodore serial networking and third-party network adapters where supported
Operating System	Commodore BASIC 4.0+
Expansion / I/O	IEEE-488, user, cartridge and model-specific expansion
Keyboard	Integrated professional keyboard with numeric keypad
Storage	Cartridge, cassette and IEEE-488/serial disk options
Sound	SID sound on P-series; limited sound on business models
Colours	Model-dependent
Graphics	Model-dependent VIC-II colour or CRTC business graphics
Display	80-column monochrome output
ROM	BASIC 4.0+ and system ROM
RAM	256KB
CPU Speed	2 MHz