Retro computing with a touch of modern and the home for all things, retroCombs (aka Steven Combs).

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23 May 2020

Commodore Plus/4 User’s Manual, Chapter 0 - Open the Box

by Steven B. Combs, Ph.D.

Today I unveil the first in a new theme of posts, retroCombs. This theme is devoted to my love of retro computing and gaming. I have a couple of retro posts on the blog, but now I have a brand theme to tie them together. The first post to receive the brand is part one of a new series on the Commodore Plus/4 computer.

MEMBERSHIP: I now offer retroCombs memberships from $1 (PET level membership) to $20 (MEGA65 level membership) that include levels in between for all budgets (VIC-20, C64, Plus/4, and C128). If you’d like to support my content and get access to my Discord server along with other cool freebies, check out each level at https://www.buymeacoffee.com/retroCombs.

Table of Contents

Series Information

This episode is part of a series. You can read the entire series and view additional resources at:


Companion Disk Image

As I progress through the user’s manual, I enter and execute sample programs. The link below is to a .d81 image that contains every program from each episode. Currently, the image is not complete since we still have several chapters to go.

retroCombs User’s Manual Disk Image - UPDATED AS OF: 2020-11-01

I use the following file name convention to make it easy to locate specific programs:

Sample Program Name: 02 RCOMBS SCROLL.PRG

User’s Manual

As part of my Commodore Plus/4 YouTube series, I work through each chapter of the Plus/4 manual. I’ve taken the time to scan each chapter so you can read and follow along. Use the link below for this episode’s chapter:

User’s Manual Front Matter

YouTube Video: retroCombs: Commodore Plus/4 User’s Manual, Chapter 0 - Open the Box

The video below describes my background with Commodore computers, my intent for this new series, and an open the box on a Commodore Plus/4. Watch the video and then come back and read the additional material posted below the video.

Key to Keys

Because the Commodore Plus/4 keyboard is so different from modern keyboards, I devised a modern key nomenclature to identify keystroke combinations as shown in the table below:

Key Description Key Description
Caps Lock F1 Function 1
[C=] Commodore F2 Function 2
Control F3 Function 3
Escape F4 Function 4
Clear/Home F5 Function 5
Insert Delete F6 Function 6
Return F7 Function 7
[R/S] Run/Stop F8 Help
Shift Space
Cursor Up Cursor Down
Cursor Right Cursor Left

Episode Errata

THANKS TO EVERYONE FOR THE FEEDBACK!!! It makes this project more fun and I’m (re)learning much. I will add video corrections or additions below.

Random Thoughts

I look forward to diving into the Commodore Plus/4. This 8-bit computer has eluded me for years. I know it is going to be a very different experience from my earlier VIC-20, 64, and 128. The lack of focus on gaming with an increased emphasis on business should be an interesting study. I’m excited to explore what appears to be a more functional basic programming language complete with dedicated graphics commands, file functions, and machine language monitor (all missing from the VIC-20 and C64).

NOTE: While writing this post, I found the Commodore Plus/4 Wiki. It will become an excellent resource during this series.

One experiment I will conduct, is to use the Plus/4’s keyboard and word processor to write a blog post. This will involve typing the post (in Markdown) on the Plus/4 and then finding a way to move the text to a modern PC. I’m open to ideas now if anyone has them!

I hope readers and watchers enjoy the series. I may not post as regularly as I like, and I may use YouTube Live on a whim to capture live experiences, so make sure you subscribe to my blog, Twitter feed, and YouTube channel if you want the full experience.

I want this to be a collaborative project. If you are an experienced Plus/4 aficionado, please share your ideas, thoughts on the content, and where I might easily (and inexpensively) locate peripherals for this device. I’d even appreciate if you have spares lying around, sending them my way.

If you are new to the device like I am, post your questions and ideas for what you would like to see. Also let me know if you are following along. Let’s make this a community project. For now, Leave your comments and thoughts below or in the comments under the YouTube video.

🕹️ retroCombs, OUT!