Commodore Plus4

The Commodore Plus / 4 was a home computer from Commodore, which came on the market in 1984. He was a model of the Commodore 264 series.

The Plus / 4 was introduced in June 1984 at a price of 299 U.S. dollars. As early as 1985, the sale was reinstated. He had greater success only in Eastern Europe, Western Europe, he was very small sales, and in the U.S., he was a complete flop. Only when the supermarket chain Aldi sold Remnants of models C16, C116 and Plus / 4 time for little money, yet few users were gained in Germany. The models of the 264 series have been developed as a simple and cheap home computer, which should make the Sinclair ZX Spectrum on the lower segment of the market competition. As the price of higher market settled C64 but fell faster than expected, was no place for a little cheaper but much less powerful computer. To gain knowledge workers as a target group, Office applications have been added shortly before the planned publication date.


The keyboard of the Plus / 4 had a completely different design than that of the VIC-20 and C64. She had a clustered separately " diamond " of four cursor keys whose operation was more intuitive than the two cursor buttons on the C64. The inspiration for this keyboard layout of the MSX standard, increasingly gained with the hardware and software side unified small computer especially in Asia in importance.

Four built- in ROM applications ( the so-called 3 1 package ) gave the Plus / 4 his name. It was a word processor, a spreadsheet, a database program and a barely usable graphics program. Added to this was a useful feature for programmers a machine language monitor. However, the applications had only rudimentary functions.

In contrast to the C64 Plus / 4 had a MOS 6551 UART chip ( the C64 emulated it in software). This allowed a high-speed modem can be connected without any special hardware or software tricks. The sister models C16 and C116 did not have this block. This was not least because the Plus / 4 Commodore was originally considered to be more professional compact office machine.

However, only few users decreed in 1984 via modems with more than 300 to 1200 baud, then held the advantage in limits because 1200 baud also managed the software emulation in C64. One of the first modems with 300/1200 baud for the Plus / 4 was produced mid-80s and marketed.

The C16 and C116 could be relatively easily upgraded to 64 KB of memory. So they were rebuilt almost completely compatible with the Plus / 4 and were able to use almost all of the programs of the Plus / 4. Excluded were practically only terminal programs that required the 6551 chip mandatory.


  • CPU: MOS 7501, 1.76 MHz
  • RAM: 64 KB, about 60 KB in BASIC available
  • Text mode: 40 × 25
  • Graphics Mode: 320 × 200 pixels with 121 colors
  • I / O port: Expansion module or port ( incompatible with C64)
  • Two joystick ports (mini- DIN connectors incompatible with the C64, adapter 9-pin standard connector required)
  • A seven- pin mini-DIN socket for connecting the 1531 Datasette ( incompatible to C64)
  • Serial IEEE - 488 bus (CBM ) bus ( compatible with C64)
  • User Port (for modem, incompatibilities with C64)
  • Audio / video output ( composite and S -Video signal, compatible with C64)
  • RF output for TV (compatible for C64)