plus 4


002 003 004 005
006 007 008 009
010 011 012 013
014 015 016 017
018 019 020 021
022 023    
(click on picture)


Above is a view of the Plus/4 main screen


Introduced June 1984
Release Price $299.99


      The Plus 4 was originally announced at the January 1984 CES as the Commodore 264. The original concept was to sell the 264 in one of several different configurations. The consumer would select the type of application software they wanted built into their computer and the dealer would install the appropriate ROM chip. By the summer 1984 CES this concept was abandoned probably due to the dealers refusal to either install their own ROM chips or stock many models of the same computer.

      The name was changed to the Plus 4 and all the applications were added at the factory. The Plus 4 was redesigned with a new look and feel. Unlike the C-16 , which is a stripped down version of the Plus 4, uses the same case and keyboard styling as the VIC/C64 line. The Plus 4 can still use the same serial peripherals as the C-64 but comes with its own peripherals. One in particular stands out, the SFS-481, a parallel floppy drive using the new parallel port on the rear of the machine allowing greater speed accessing programs. The Plus 4's cassette and joystick ports are not compatible with the C-64 line.

      The Plus 4 is lacking a few significant feature found on its older sibling the C-64. Although it improved on the color capabilities, increasing them from 16 to 128 possible colors and adding 12 more sound and graphics commands in BASIC, it is missing the 8 sprites and sophisticated SID chip found on the C-64. The reason for the lack of sophisticated gaming capabilities was probably the Plus 4 was targeting a segment of the home market interested in more serious applications programming. The Plus 4 was not a very good seller mainly due to its incompatibility with the C-64 and the price drop of the C-64 made the 64, which could do basically every thing the Plus 4 could do cheaper, an exceptional value dooming the Plus 4.

System Architecture

Microprocessor 7501
Clock speed 1 MHz
Bus type CBM proprietary
Bus width 8
Interrupt levels N/A
DMA channels N/A


Standard on system board 16k
Maximum on system board 16k
Maximum total memory 64k
Memory speed and type 200 ns
System board memory socket type  
Number of memory module sockets  
Memory used on system board dynamic
Standard Features   ***** Disk Storage  
ROM size 20k   Internal disk and tape drive bays no
Optional math coprocessor no   Standard floppy drives optional
Parallel port type CBM   Optional floppy drives: yes
RS232C serial ports yes   * 5 1/4 inch 160k up to 8
Mouse ports yes   * 5 1/4 inch 1.2MB no
UART chip used N/A   * 3 1/2 inch 720k no
Maximum speed N/A   * 3 1/2 inch 1.44MB no
CMOS real time clock no   * 3 1/2 inch 2.88MB no
CMOS RAM no   Hard disk controller included no
Video & Graphics     Sound  
Graphics Processor     Sound Interface device  
Screen size - Col x Rows 40 x 25   Sound generation  
Resolution - Colors/High 128/320 x 200   ADSR capable no
Resolution - Colors/Low        
Max colors 128   Programming language  
Sprites or Missiles no   Built in language CBM Microsoft BASIC 3.5
      Built in M L monitor yes
Expansion Slots     Keyboard Specs.  
Total adapter slots 1   Number of keys 59
Number of 8/16/32 bit slots 1/0/0   Upper/lower case yes/yes
      Keyboard cable length N/A
Physical Specs.     Environmental Specs.  
* Height     Operating voltage @ 60 Hz 105-125 VAC
* Width     Maximum power supplied  
* Depth     Power supply output - volts  
* Weight     Power supply output - amps