This 60 page doc covers all three of the 1541 Ultimate units (1541u, 1541u II, 1541u II+).

This documentation is basically for all three of Gideon's supported hardware [1541 Ultimate II, 1541 Ultimate II+ & Ultimate 64] projects using firmware up to v3.7 (Which is 1.28 on the Ultimate 64).  Anyway, you can find the most current documentation here online.  The reason I put snapshots of it online is because someday (possibly) someone will want to look back and see the progression of this awesome piece of hardware.

ARM2SID is a new replacement for 2 Commodore SID music chips and more. ARM2SID is a bigger brother of our well known ARMSID, which is a real "plug & play" solution and fully replaces both the MOS6581 and MOS8580 chips.
ARM2SID comes whenever 2 SID chips are needed, usually for stereo. If you have 2 SID sockets, just place the ARM2SID in the primary socket, SID2 in the secondary socket, connect both of them with the provided 5 or 10 cm cable, configure with the provided C64/C128 utility and go.
If you have just one socket and are not afraid of soldering, you can get even more. Use the provided connector cable, connect the 6 wires to your C64/C128 and you get the 2nd SID for stereo, the 3rd SID for 3SID music and OPL FM synthesis compatible with FM Sound Expander!
Enjoy your ARM2SID!

Despite rumors of a forthcoming 'paperless' society brought about by the innovations of electronics technology, computer user of today still derive much satisfaction and have great need for seeing the results of their efforts on a hard copy printout. This introductory section is provided to offer some general observations on what printers are and how they work. It is intended as an introduction for novice users and a base upon which they can expand their knowledge.

Cannon BJ-200e Printer User's Manual

This manual and the programs on the cassette show you how to use the Cardriter 1 Light Pen for selecting items from a menu, for responding to prompts, for answering multiple-choice questions, and for playing games. We'll also give you details on programming for the light pen and on how the pen works.

CBUS stands for Cartridge Back-Up System. CBUS I produces backup copies of cartridges for the Commodore 64. Using CBUS I saves wear and tear on ths Commodore 64  expansion connector by tricking the computer into running an image of the cartridge without having the cartridge physically present. Up to 17 cartridges can be stored on a single diskettae. With CBUS I, cartridges can be storad out of harms way rather than cluttering up the work area. CBUS I incorporates a RESET switch allowing you to perform a COLD Start without having to turn the machine off and on again. This permits study of cartridge object code, opening up the possibility of custom modifications.

The CMD FD-2000 and FD-4000 are 3.5 inch floppy disk drives which have been designed utilizing the latest in micro-floppy technology. While retaining backward compatibility with Commodore 1581 formatted diskettes(800K), these drives are also capable of utilizing high density (HD) disks fora storage capacity of up to 1.6 Megabytes. The FD-4000 model can also use the newer enhanced density (ED) diskettes for a storage capacity of up to 3.2 Megabytes.

The CMD HD has been designed to be the easiest-to-use hard drive system available for Commodore 64 and 128 computers.

CMD RAMLink extends the capabilities and compatibility of RAM expansion units for the Commodore 64 and 128 series of computers.

I have one of these adapters and although it's not the 5.1 version, I figure someone else might benefit from the manual, so here it is.

Find much more info here.

The Commodore 1351 Mouse is a controller designed for use with the Commodore 64 or Commodore 128 computers.  It features two buttons on the top, and a ball on the underside that is rolled upon a flat surface to manipulate on screen activity.

Basically, this manual is divided into two parts. The first part includes the introduction, mouse cleaning, and tips for general care of the mouse. That part is for the user with mouse-compatible software, who wants simply to plug in the mouse and begin using it. The second part of the manual contains information needed by those who wish to develop software for the mouse.

Commodore 1764 RAM Expansion Manual.

Commodore MPS 1200 Dot Matrix Printer User's Guide

Commodore MPS 1230 Dot Matrix Printer User's Guide

Commodore MPS 1250 Dot Matrix Printer Manual.

Commodore MPS 802 Printer User's Guide

Commodore MPS 803 Dot Matrix Printer Users Guide - A Friendly Introduction to Your MPS-803 Dot Matrix Printer

Commodore MPS-1000 Dot Matrix Printer Manual

You've made a wise purchase... the Plus/4 is the first home computer ever designed especially for productivity applications.  Of course, it's still able to do all the other things a home computer can be used for. This manual is designed to help you learn those "other things" yourPlus/4 can do.

Epyx FastLoad Cartridge Manual

The EZ-232 Interface, designed by Jim Brain, provides a low-speed serial port for Commodore 8-bit computers. It can operate at speeds of up to 2400bps, when configured as a standard interface, and at speeds of up to 9600bps, when configured as a UP9600 interface.

Final Cartridge III User Manual [English]

** Nice webpage with pictures of the original and newer Final Cartridge III+ . Also check out the Wiki for more details.

IDE64 Instruction Manual for v0.89

IDE64 Users Guide [February 24th ,2019]

Complete & searchable PDF version of the JiffyDOS v6.01 Users Manual.

Kerberos MIDI Flash C64 / C128 Interface Developer's Guide

KeyDOS ROM is a chip that contains 20 new function key definitions and 20 great utilities. KeyDOS ROM is easy to install in the empty ROM socket in any C128 or C128D. KeyDOS ROM can also be installed in the space for an empty socket in Commodore 1700, 1764, and 1750 RAM Expansion Units.

MAGNUM LOAD!  Doesn't that just sound official... I mean seriously, do you want just another "fast load" or something serious like MAGNUM LOAD!

Master Adapter Supplement [Turbo Master]

Comprehensive documentation of all BASIC 65 commands, functions and operators for the Mega 65 computer.

Please visit the official Mega65 files page to get the latest version.

This refence describes the MEGA65’s native memory map, that is, where all of the memory, I/O devices and other features appear in the 28-bit ad- dress space. We will then explain how C64 and C65 compatible memory maps are accessed from this 28-bit address space.

Please visit the official Mega65 files page to get the latest version.

Congratulations on your purchase of one of the most long-awaited computers in the history of computing.The MEGA65 is a community designed computer, based on the never-released Commodore® 651computer; a computer designed in 1989 and intended for public release in 1990. Decades have passed, and the MEGA65 invokes an earlier time when computers were simple and friendly. They were not only simple to operate and understand how they work, but friendly and approachable for new users.

Manual / Docs for the Mini X-Pander by Arkanix Labs.  The Mini X-Pander is a cartridge port expander for the C64 / 128 that lets you use more than one cartridge at a time.  It also includes a reset switch.

The miniGANGCART cartridge supports fast loading and writing procedures for stations 1541, 1541C, OCEANIC 9900, 1541II,1570/1571 (in GCR1541 mode) and 1581, SD2IEC for the PAL / NTSC Commodore 64 version. The area that can be uploaded and burned using quick procedures is included in almost the entire C64 memory, that is from $0400 to $ FFFF.

Users manual for the MMC Replay (updated 2/7/2008 - BIOS v0.51).

Congratulations on your purchase of the NEOS MOUSE & CHEESE.  The NEOS MOUSE is an excellent input device with which you can give various instructions singlehanded to a computer while watching the TV screen,etc.  Before using the mouse read this manual carefully to get the most out of the NEOS mouse and the software ''CHEESE".

Network Flyer (http://retroswitch.com) User's Guide v1.1

The OC-118N Disk Drive is a versatile and efficient disk drive built for the Commodore series or personal computers. This drive is fully compatible with the Commodore 64 computer and directly replaces the Commodore 1541 Disk Drive, giving much better performance in terms of data loading and writing speed and memory buffer size.

Your OKIMATE printer can print almost anything you create on your Commodore computer screen: letters, reports, charts, and graphic designs (in black or in color). It can underline phrases, print them in italics, or write them in eyecatching headlines. With its superscripts and subscripts, OKIMATE can print footnotes, exponents for math problems, and chemical formulas.

This printer handbook explains all you need to know about setting up and printing with OKIMATE. Just read through these first few pages, and OKIMATE will soon print its self-test pattern, and demonstrate its printing style for you.

This handbook will help you install and use your new OKIDATA printer. It contains everything you need to know to print with your OKIMATE's special features.

The SaV64 is an over-voltage protection device for Commodore 8-Bit computers that require both 5VDC and 9VAC power sources. It monitors the 5VDC voItage level and automatically disconnects both the AC and DC from the computer when it rises above the trip voltage.

Note - This manual is from 2017 and came with batch 4 of this product.  Future versions may be different.

Lemon64 forum thread 

YouTube video

This is the users manual for the SDrive 1564 which is SD card based drive emulator.

Congratulations on having purchased a serial, impact dot matrix printer that offers you more quality, greater flexibility and convenience, and superior reliability than you could find in any other printer in the same price range. As you already know (or are about to learn), the Gemini-lox and Gemini-15X let you print both regular and italicized alphabets, as well as normal, elite (smaller), condensed, enlarged, emphasized, and double-strike characters. You can print on regular stationery, multiple-sheet forms, fanfold computer paper, or paper fed from a roll (European style).

The graphics capability provided by the Gemini printers is limited only by your graphic talents, and includes three bit-image modes: Low Resolution (60 by 72 dots per square inch), High Resolution (120 by 144) and Ultra High Resolution (240 by 144). With all this printing power at your fingertips, what are you waiting for? Let’s get started!

This User’s Manual is organized to serve both the first-time user and the sophisticated computer buff. The first five chapters provide the basics you need for putting your printer to work in most home and office applications. Chapters 6 through 10 deliver information for intermediate and advanced users, supported by technically rich appendices. If you are a beginner, you might want to look at Chapters 6-10 sometime in the future, when your curiosity about how the printer does what it does has replaced your initial interest in what it can do.

The graphics capability provided by the Gemini printers is limited only by your graphic talents, and includes three bit-image modes: Low Resolution (60 by 72 dots per square inch), High Resolution (120 by 144) and UltraHigh Resolution (240 by 144). With all this printing power at your fingertips, what are you waiting for?

Star Micronics NP-10 Printer User's Manual

Congratulations on your selecting the printer of choice for both the sophisticated as well as the first-time user/owner - the new SG-10C!  Your new printer offers full compatibility with any Commodore on the market.  It combines the speed and efficiency of a proven winner with the character sets and printer codes used by the Commodore!

This interface cartridge contains all the electronics your printer needs to talk to a computer. To use your printer with a different computer, just install a different cartridge. There is an interface (I/F) cartridge for each popular computer on the market.

This interface cartridge offers full compatibility with any Commodore on the market. It combines the speed and efficiency of a proven winner with the character sets and printer codes used by the Commodore!

Star NL-10 Printer User's Manual

Star NX-10 Printer User's Manual

These installation instructions describe the installation of theStarDOS system into your disk drive and computer.  If your StarDOS was installed by your dealer, then skip this!

StarDOS Cartridge manual by Starpoint Software (1988)

The Super 1750 Clone was a 512 kB RAM expansion unit designed as a tiny, but compatible, third-party replacement for Commodore's then out-of-production CBM 1750 REU. Manufactured by Chip Level Designs, the Super 1750 Clone was sold by Software Support International.

Manual for the CMD SuperCPU 128 V2 Accelerator for the Commodore 128. 

Turbo Chameleon 64 Docking Station Install Notes

With the purchase of a Commodore VIC Printer, you have added a great deal of versatility and convenience to the use of your Commodore VIC-20 Computer.  While this manual contains all the information you need to check out, connect and operate your printer, you should also refer to other Commodore manuals to get the most out of your computer system.

VIC-II² Installation Instructions v1.0 (Updated Dec 11, 2022) - This is a detailed set of instructions on building and installing the "VIC-II Squared" hardware that allows you to have both an NTSC and PAL VIC-II chip installed in your Commodore 64, giving you the ability to switch between them.

Here's a link to a YouTube video that also details the contruction and installation