I have been interested in computers since the days of the IMSAI, and I have a classic IMSAI VDP80 in storage. The IMSAI VDP80 was an integrated unit which included an early S100 Bus, monitor, 54k Ram (Max) and a Couple very unreliable PERSCI 8" floppy drives all in one large steel box. The unit weighed in at around 110 pounds and sold for $7-9,000.00 US.
Most writers mention the IMSAI along with MITS/ALTAIR when speaking of the the very first successful micro-computers. We never thought of calling them a PC until IBM invented the Personal Computer, some years later.
The IMSAI VDP-80 was the very first micro computer shipped fully assembled and ready to go. Prior to this product you had to buy a kit and 'roll your own'. They were the top seller in the industry in 1977 and were bankrupt in 1979. The VDP-80 featured an INTEL 8080a CPU running at around 2 Mghrz.
Bundled software included an operating system called IMDOS which was an OEM variant of CP/M, as well as BASIC-E, the public domain fore- runner of CBASIC.
These very early computers have a lot to do with whey computers look like they do today. For example, computers such as this well preceded the general availability of what we now call a hard drive, but which when they first came out were called 'Winchester Drives. Of course even the name 'Winchester' has a story behind it. It is reported that the first very early small fixed drives had parameters of '30-30". I've long forgotten what the parameters stood for, but one of the most famous rifles made by Winchester was a Model '94 30-30. The Winchester 30-30 Carbine was a very good saddle gun, and in case you haven't guessed the '94 stood for the year of its release and it wasn't 1994 either. In rifle talk the 30-30 parameters represented the size of the bore--30 caliber, and the powder load--30 grains of powder.
It was a good saddle gun because it had a short barrel so it would fit in a scabbord nicely, and was lever action so you could easily take several shots without reloading.
Returning to the point, however, it was customary for computers with floppy drives to have 2 of them, because otherwise you couldn't make backups, as the utilities which purport to let you duplicate a floppy in a single drive didn't exist and wouldn't work anyway very well because the computers had so little RAM as to provide almost no place to store anything while you switched disks as is necessary in a 1 drive backup program. it became customary to call these floppy drives A and B. It was only logical when a winchester came along, that it would be 'C'. Drive C is now almost universally the first harddrive for this reason and is hardly ever called a 'Winchester' anymore.
Although one of the features of the VDP_80 was a memory mapped video card, the standard of the era was for the use of a serial terminal for a monitor. This is because that is what existed. As the operating system was first developed Gary Kildahl actually used a 'paper terminal' which explains why the early utilities were 'line editors'. These teleype devices were what was available and the telecommunications industry used them so that was what was available. The 'glass teletype' or serial terminal as we know it today came later.