This is a straightforward advert from SWTPC - South West Technical Products Corporation - which originally made its name as a supplier of electronics kits, for the company's Motorola 6800-based computer of the same name.
The machine, as advertised, came with a serial connection for plugging in a terminal (available at extra cost), from which "data may be entered ... in convenient hexadecimal form" - in pretty much the same way as machine-code programmes would be painstakingly and tediously transcribed out of magazines by proto-programmers during the home computer explosion of the early 1980s.
[picture: machine_code.jpg|Part of a hexadecimal machine-code program for a Z-80 processor (in this case a Sinclair Spectrum). The longer number at the start of each line is the memory location each line of hex started at, the short pairs are the actual code - two bytes at a time. These would often be printed out in computer magazines and would be typed in by hand on the owner's computer. They rarely worked first time, and debugging meant checking every character again, one by one. They were also specific to only one (or at best a few) models of microcomputer. From PCN, March 2nd 1985]The price of $395 (about [[300|1977]] in [[now]] money) remained the same at least until the following year, when the same system was being advertised with additional peripherals such as a disk drive and a terminal.
2K (2048 bytes) of memory was still perfectly sufficient for a small computer in 1977 - the year that the "trinity" of the Commodore PET, Tandy TRS-80 and Apple II launched.