Homebrewing, as the name suggests, is the designing and building of computers, from the ground up, or sometimes from kits. Some homebrew systems have gone on to be the basis of commercial designs. Most early microcomputers were available for construction with levels of commercial component support varying by cost, or as published designs only, usually with a range of options in construction.
[wiki="Image:TVT_Prototype.jpg"]|thumb|right|alt=Early Microcomputers|Early micro systems were often home brew to one degree or another. Included here is the homebrew prototype for the TVT-1 (lower middle) and the COSMAC Elf project (lower left.)[/wiki]
Some vintage computer enthusiasts consider homebrewing to be an important aspect of the vintage computing hobby, giving new enthusiasts an opportunity to experience more fully what the early years of hobby computing were like. There are several different approaches to this end. Some are exact replicas of older systems, and some are newer designs based on the principals of vintage computing, while others combine the two, with old and new features in the same package. One such example is offered by IMSAI, a modern, updated, yet backward-compatible version and replica of the original IMSAI 8080, one of the most popular early personal systems. Several Apple 1 replicas and kits have been sold in limited quantities in recent years, by different builders, such as the "Replica 1", from Briel Computers.
Current projects that use old technology in a new designs are the Z80-based [wiki]N8VEM[/wiki] and [wiki]MAG-85[/wiki], based on the 8085 processor. The N8VEM, designed by Andrew Lynch, is the base of a full-featured system capable of running CP/M, and which is easily expandable. The MAG-85, designed by Mark Graybill, is intended as a limited system, akin to the microprocessor trainers and development systems of the 1970s and 1980s.
[h="2"]Traditional Homebrew Systems[/h]
Another approach for many enthusiasts is to design their own systems from scratch, using design principles such as those presented in Steve Ciarcia's "Build Your Own Z-80 Computer"
. Or, constructing new computers original project designs such as the [wiki]COSMAC Elf[/wiki] or the reference designs presented in manufacturer's hardware manuals for microprocessors.
[h="2"]Value of Home Brew Construction[/h]
Aside from its value as a form of historical re-enactment, building from scratch teaches the builder new lessons about the operation and maintenance of computer systems. The purpose and operation of individual circuit components must be understood. Troubleshooting techniques must be employed that cannot make basic assumptions about the design or construction of the system, requiring a deeper insight into the circuit, its operation, and the details of its assembly.
Homebrewing may be the only technique for obtaining some systems for use. Certain vintage systems are practically unobtainable, or prohibitively expensive to the hobbyist. Or, a system based on an unusual chipset or architecture may be desired, such as a system based on the 16032 processor or a system built around the SS-50 bus.
A homebrew system may be the best approach for integrating desired feature sets. For example integrating a classic processor with modern memories, storage systems, or support processors may be best achived through a clean sheet design rather than through interfaces to older hardware.
[h="2"]Usage of the Term Homebrew[/h]
The term "homebrew" or home-built varies in usage. In its strictest form, it refers constructing a system of one's own design using only general purpose or self-made components. Looser uses of the term include the use of established designs and prefabricated design-specific components such as printed circuit boards and preprogrammed memories and logic. In general it can be applied to any construction of a computer system at the sub-board level. A system assembled from prefabricated boards is not considered to be homebrew, unless extensive modification or repurposing of those boards for the construction of a unique system has been performed.
===Homebrew Design Principles===
[h="3"]Homebrew Design Collections[/h]
[h="3"]Updated Versions of Vintage Designs[/h]
[h="3"]New Vintage-Style Designs[/h]