Computer Based SSTV
Computers have been used for sending and receiving SSTV since about 1976. Since SSTV is audio based, it does not take a very powerful computer to produce a satisfactory SSTV picture. Many different types of computers have been used over the years, but the most common ones now are what are called "IBM PC Clones", or just "PCs". Pictures are very memory intensive, but memory costs are very low, and even the high resolution color SSTV images of today only take about 10K to 300K of memory, depending on the amount of compression. A 15 GB hard drive today goes for about $100, and could store between 50,000 and 1.5 million SSTV pictures!
SSTV computers can belong to either of 2 groups. The most common are desktop units built in metal boxes, somewhat RF tight. The other type are called Laptops. Originally they really would fit on your lap, but now they are usually too big due to a larger LCD screen. Maybe they test them on larger laps now. The same capability in a laptop will cost ~$1000 more.
AMD K6-450 with 20 GB, 16X CDROM, & CDROM-RW Toshiba Satellite 200 with Pentium 100 & 2GB
An SSTV computer has 4 tasks. It must generate the SSTV for transmit; it must demodulate the SSTV for receive; it must display the transmit and recive images; and it must store the image. With the current generation of computers, it would be difficult to find one for over $200 that would not work just fine.
The PCs require software to operate. This software has several layers. The computer has internal firmware called a Basic Input Output System (BIOS) that tells the computer how to internally run the various pieces of fundamental hardware inside the box such as the CPU ICs, memory, and the various disk drives. The BIOS is provided when you buy the main motherboard inside the computer. The next layer up is called the Operating System (OS), that coordinates all the activities of the computer. This you buy, generally as part of the whole package. Wild Willy Gates & Microsoft became billionaires by providing this. 25 years ago it was called the Disk Operating System (DOS) which was character based and over the years evolved to support the ever more powerful microcomputers. About 10 years ago a graphically based system called Windows, originally developed by Apple computer, was conveniently provided by Wild Willy. It has developed in several stages as "Windows 3.0", Windows 3.1", "Windows 95", "Windows 98", "Windows 2000", up to the current disaster, called "Windows ME".
SSTV software developers write their software routines to utilize the lower layers to hopefully produce a seamless product that never fails. At least that's the plan. Just like there is no perfect automobile, so too there is no perfect software. But whereas the automobile has recalls where the manufacture pays the cost, in software they call it an upgrade that you get to pay for it. But then that's why Wild Willy is a billionaire, isn't it?
The computer hardware should have certain minimum components installed to function well on SSTV.