This step is optional, but will help you focus your efforts in starting a collection. It will help you greatly if you decide beforehand what you want to collect. This will also be a determinant of how easy it will be to build your collection, as some categories may be harder to fill than others. Here are some sample categories to get you started:
> Computers and software from a specific set of dates (eg, computers and software from between 1980 and 1990)
> Software made for a specific purpose (eg, compilers, productivity software, or games)
> A specific type of computer (eg, just IBM clones or only Apple Computers)
> Specific types of hardware or peripherals (eg, joysticks or modems)
> Historically important computers and software (eg, IBM 5150, Apple II, Commodore 64, Visi-calc, MS-DOS 1.0)
> Computers made for a specific purpose (eg, DOS gaming computers)
The list of possible categories are endless.
This is probably the most surefire way to find something you want. If it exists, then you'll probably find it on eBay. However, the kind of person who sells old computers on eBay is the kind of person to know what their computer is worth. You likely won't be getting a good deal on whatever you buy here. Additionally, you should always be aware that most old computers and software on eBay are sold 'as is'. There is no guarantee that they will function, meaning that you could pay through the nose for a rare floppy disk only to find out that it has deteriorated.
CRAIGSLISTCraigslist is a good way to find old computers and software, but it comes with the same warning as eBay. If someone is selling it on Craigslist, they probably know its true value. That said, you can get an excellent deal on things if the Craigslist deal is of the "I have a bunch of random stuff I'm selling, come on over and make an offer" type. These people are selling things merely to make space. In all likelihood, they don't know precisely what they have. The only downside is that finding old computers and software in an offering like this is rare, but that doesn't mean you shouldn't check anyway.
GARAGE SALESIf you're ever driving around and you see a sign advertising for a "Garage Sale", then this could be your lucky day. These people are seeking to get rid of all their 'junk', so you can get it for a steal. If you don't see anything you want, don't despair. Oftentimes, if you ask the owner, they may have more items that aren't on display, or they may be able to refer you to a neighbor who might have what you want. The best places to find old computers and software is in a garage sale in an older neighborhood. The older the neighborhood, the more likely the owners are to have older items for sale. They may have even bought the computers and software themselves, so you'll be getting better quality items.
SWAP MEETS AND FLEE MARKETSThese can be pretty hit-or-miss. If it's a specifically computer-themed swap meet, you're less likely to get a good deal on whatever you buy. However, general electronics swap meets can be great. If there's a local electronics recycling organization in your area, check if they sell the items that get donated. These organizations simply want to make a few bucks. It's not unheard of to get a complete rare computer + software for less than $5 from one of these events.
GOODWILL STORESThese are generally not a very good place to find old computers. They get picked over very quickly by seasoned veterans. However, there's always a chance that you'll find an exceedingly rare computer that somebody just gave away.
Despite your best efforts to keep your software in good condition, there is the inevitable likelihood that your floppies, cassettes, and cartridges will decay and lose data. Archiving this data is an important part in maintaining a collection, as it allows you to share your collection with future generations if you decide to put it on the internet. There are a variety of historical software archives on the internet, each one dedicated to a specific computer or architecture. While it's a legal grey area to redistribute proprietary software in this way, it's generally permitted since most of the companies that made the software either went out of business, or don't make any money off that product anymore. Through these online archives, you can download disk images of software that you don't have, allowing you to transfer them onto a medium and try it out on your original machine! Here are a few ways you can transfer your software between the internet and your old computer:
ARCHIVING CARTRIDGESSome software back in the day was placed on cartridges, and this is the storage medium that holds up the best over time. The carts had ROM that was flashed to hold the program data. It's generally hard to get information off of these carts, but you can use a cart dumper to do it for you. Cart dumpers are specific to the system the cart belonged to, so no one solution will work on all carts. Most of the time, you can find a project somewhere online where a person used an Arduino or other device to dump the contents of the cart. If they posted their code, then you can do it too.
ARCHIVING CASSETTESSoftware on cassette was popular back in the day. Cassettes are generally the easiest storage medium for archiving, since there are so many products that are still made today to read and write to cassettes. If you want to back up your data from a cassette, just buy a cassette player. Plug an audio cable from the headphone output of the player into the microphone jack of your computer. Then, with your favorite audio recording software, start recording on your computer, and play the cassette. You now have an audio file of the program saved on your computer. If you listen to it, it probably sounds like a screeching animal. To transfer back to cassette, plug the headphone jack of your computer into the microphone jack of your cassette recorder. Start recording to the cassette, and play the sound from your computer. You will probably have to mess with the playback audio levels to get a program to work, because if you play it back too loudly or too quietly, the program data doesn't get picked up properly.
ARCHIVING FLOPPIESFloppies can be pretty hit-or-miss with archival, and it really depends on the type of floppy. If it's a 3.5" floppy, then you're fine. You can buy a USB to 3.5" floppy drive for $20 and read/write the disk with that. If it's a 5.25" floppy, then things get more difficult. There are no commercially produced USB to 5.25" floppy drives. However, that doesn't mean that there aren't solutions. If you're specifically trying to get a Commodore 64 floppy to/from a modern computer, then you can buy a USB controller called Zoomfloppy. It costs around $40 and goes from USB to a C64 floppy drive. There are libre drivers that go along with it, and it works on all major operating systems.
When archiving 5.25" DOS disks, things get even more complicated. If you're using a desktop computer and you have a spare drive bay, then you may be able to install a 5.25" drive and connect it with a ribbon cable. Chances are, your OS will still have drivers for it. If you don't have the space, then this solution won't work. If your collection contains a DOS computer with both a 3.5" drive and a 5.25" drive, you can write the data to a 3.5" floppy with the aforementioned USB drive, and then use the DOS computer as an intermediary to write the data from the 3.5" drive to the 5.25" drive. This also works in the reverse direction to go from 5.25" to modern computers. If you don't have a computer with both a 3.5" and 5.25" drive, then you'll have to rely on an external USB controller. There is one device called the FC5025 which costs about $60. It can interface a modern computer with a 5.25" floppy drive and works on more than just DOS disks (Commodore, Apple, and more are possible). The only downside to the FC5025 is that it is read-only. This is fine for pure archival, but if you want to be able to transfer a disk image you found online to your computer, you need something else. The Kyroflux is a USB to floppy controller that has read and write abilities. It's definitely on the pricey side, with its the cheapest version costing 95 euros (~$110 at the time of writing).
> Play games on original hardware
> Share and preserve computing history
> Write software for old systems
> Learn the history behind the pieces of their collection
> Install a new operating system
> Cluster it with every other device you own and use the cluster as a server
> Build a sleeper PC, modern hardware in an old, crusty case