Commodore Plus/4 Typical Boot-up Sequence Explained

This article details the standard startup process of the Commodore Plus/4 computer. It covers the power-on self-test, the display of the BASIC V3.5 interface, and the access to built-in application software. Readers will learn the specific steps and screen outputs that defined the user experience during the initial boot sequence.

When a user flipped the power switch on the Commodore Plus/4, the machine immediately began its initialization process driven by the TED (Text Editing Device) chip. Unlike some contemporary systems that displayed a blank screen for several seconds, the Plus/4 was designed to provide rapid feedback. The first visual indication of a successful power-on was the clearing of the screen to a solid blue background, which was the default color for the BASIC environment on this model. This distinct color scheme helped differentiate the Plus/4 from the cream and blue palette often associated with the Commodore 64.

Following the screen clear, the system performed a quick memory check. The Plus/4 came equipped with 64 kilobytes of RAM, and the boot sequence verified this capacity almost instantaneously. Once the hardware check was complete, the computer displayed the startup banner text in white characters against the blue background. The header read “**** COMMODORE BASIC V3.5 ****,” indicating the upgraded version of the BASIC programming language embedded in the ROM. This version included improved sound and graphics commands compared to the BASIC V2.0 found in earlier Commodore 8-bit machines.

Below the version header, the system reported the available memory status. The standard output displayed “64K RAM SYSTEM” followed by the specific number of bytes free for BASIC programming, which was typically 38911 bytes. This count was slightly lower than the total physical RAM due to the memory reserved for the video display, system variables, and the unique built-in software suite. The sequence concluded with the cursor blinking on a new line accompanied by the word “READY.”, signaling that the computer was awaiting user input.

A defining feature of the Plus/4 boot experience was the presence of the “3 Plus 1” software suite. This collection included a word processor, spreadsheet, database, and graphing program, all stored in the computer’s ROM rather than on external cartridges or disks. While the machine booted to the BASIC prompt, this software was always resident in memory. Users could access these applications through specific system commands or menu structures without needing to load external media, streamlining the workflow immediately after the boot sequence completed. This integration aimed to make the Plus/4 a productivity tool right out of the box, distinguishing its startup utility from purely gaming-focused contemporaries.