What did we use before USB? | Nostalgia NerdJun 25, 2021
We pretty much connect everything via USB these days. Keyboards, mice, speakers, phones, and even game consoles all work with USB. But
whatdid we do before this miraculous connection became commonplace? Well, that's
whatI'm here to explain. USB, also known as Universal Serial Bus, was designed by a consortium of manufacturers in January 1996, with the intention of standardizing the connection of computer peripherals, which at the time used a number of different methods dating back to the original . IBM Personal Computer. Well, I say it goes back to, but almost all of these standards were already established, like the Centronics parallel port in the 1970s and the RS-232 port in 1960 by the Electronic Industries Association, but we'll get to those in a little bit. these standards, such as IEE1284 developed by Centronics for parallel communication, were introduced before the IBM PC, but it was IBM's adoption that cemented their use.
Released in August 1981, the IBM personal computer was assembled from many OEM off-the-shelf parts, incorporating a custom BIOS, but with the rest mostly made up of third-party manufacturers. To connect the keyboard, a 5-pin DIN plug was chosen, a connection somewhat standardized in computing in the early 1970s by the Deutsches Institut fur Normung. This connection was robust, provided ample shielding, and was usually the only connector to be soldered directly to the motherboard, although early machines also included a cassette port, again a DIN connector, as a low-cost method. to load software, common on home computers of the time. This meant that peripherals such as a mouse, printer, modem, or even your monitor had to be connected via expansion cards.
These expansion cards plugged into 8-bit expansion slots on the motherboard, which would come to be called industry standard architecture or ISA slots. This name was adopted because the IBM PC spawned many clones, after all, once the BIOS was reverse-engineered or copied via observation, the other components could be purchased from third parties, and the market was soon born. IBM PC compatible, and flooded with machines. IBM's model PC would become the most powerful AT machine, with the clones of course following suit, but in all of these machines, you'd typically find a video card, to connect your monitor, a serial card, which offers one or two serials. or communications ports or RS-232, and a parallel card, although many times it was combined with the serial card.
The original IBM machines had slightly different connections, but this is the typical configuration that the IBM PC would evolve into. So, we've got the basics hooked up, but what about everything else? Well, let's start with the mouse. You could connect that to a serial port. Your computer identifies these as COM ports, and typically your mouse would have a 9-pin serial connection. Plug it in, install a mouse driver in the operating system of your choice, and you have a magic cursor on the screen. If you don't have a 9-pin serial port, you can always use an adapter and connect your mouse to a 25-pin serial port.
This was the original serial port design, with the 9-pin model introduced by IBM-AT offering a smaller footprint and more cost-effective connection using a subset of the full serial port standard. For most devices, this connection was more than enough, although its design means it can easily be mistaken for a DB9 joystick connection, as seen on the Sega Mega Drive, for example. If you want to connect a device like a modem, you'll probably need a full 25-pin port, with the full serial port specification. Many and indeed most devices could be connected via the serial port, but the main issue here was speed.
The clue is in the title, since the data is sent in a single stream, rather than simultaneously at the maximum speed, typically 115,200 bits per second. It can go higher depending on the hardware, but in general, most software didn't support it. So what about the parallel port, or the Centrionics parallel port more specifically? Well, while the original ports could only muster 150 kbit/s, the later improved and extended parallel ports could handle up to 2.5 MB per second. Unlike most serial port applications, data is sent across multiple of the 25 pins simultaneously, making it an ideal choice for printers and even high speed demanding devices like ZIP drives and other devices. storage, which take advantage of bidirectional modes in later releases. improved ports.
But this parallel communication had its own problems. The main one is that the 8 data lines needed to be synchronized with each other. So pushing 8 bits faster and faster on these pins could cause some timing issues, limiting transmission speeds. USB, for example, uses serial communication, but with technology that allows for much faster transfer speeds than our trusty serial connections could achieve. Of course, this technology also allows us to have lots of USB ports and even extra hubs, but going back to our serial and parallel ports, your typical computer may only have one of each. The problem is, of course, what if you want to connect something else?
All your ports are gone. Well, during 1987, IBM stepped in again and launched the PS/2 connection. This did away with the keyboard's bulky DIN port while also giving your mouse its own dedicated connection. However, this implementation was not widespread. In fact, it was designed to be the complete opposite. IBM was fed up with competitors stealing a market they essentially created, so in April 1987 it launched the IBM Personal System/2. This range was designed to replace their previous models, and as part of the package it had a proprietary architecture, part of which was the PS/2 ports. The keyboard interface was electronically identical to the AT interface, with a smaller 6-pin mini-DIN.
The BIOS also added routines for the dedicated mouse port. The range wasn't hugely successful, but dedicated ports became popular and would start to appear on rival machines throughout the '90s. They were particularly useful for laptops (for example), which couldn't always accommodate larger ports. . Just to add an extra layer of complication. Microsoft also had its own mouse port design, known as the "Microsoft InPort". This port was usually provided by an 8-bit ISA card and provided a mini-DIN port, similar to those found on PS/2 machines, but with a 9-pin layout. But again, this was yet another add-on card, when expansion space may have been at a premium.
Fortunately the change was coming. Although it was common at the time to have separate breakout cards to manage these ports, including obscure ones like this Tandy all-in-one adapter, from this point on it became common to see COM and parallel ports have their own header. on the motherboard, like this rather dirty example. Reducing the need for expansion cards and beginning the transformation of packaging most connections directly on the motherboard, as is common today. Well, we already have our printer hooked up, a modem for a sweet, sweet bulletin board, or even early Internet access and a mouse to navigate Windows '95.
What about the sound? Well, that hasn't changed much at all. Sound cards of the day used to have numerous 3.5m jack inputs and outputs, but since they were staged as a gaming or multimedia accessory, they usually had this as well. This is a 15 pin game port. It was originally introduced on the game controller adapter - a separate board for the IBM PC, in the mid-1980s it was often added to serial or parallel expansion cards, but in 1989 it made its way to the first Sound Blaster card , allowing the connection. of joysticks, but also by making use of the redundant pins 12 and 15, it also allowed a MIDI adapter to be connected.
The Sound Blaster quickly became the most popular sound card, with many clones following suit. So with that, our PC is connected and ready for action. But this is not the end of this story, there were a multitude of other ports that could be thrown into the mix, allowing for additional applications. You can buy a SCSI controller to connect CD-ROM drives, scanners, or even hard drives. You could even buy a multitude of products that require their own custom expansion cards, which means you could not only run out of slots, but also out of system resources. It's with all this complexity that it led Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel to come together in 1994 and have some good thinking.
Custom and incompatible connections were not in anyone's favor, so in a great example of companies working together to solve a problem, representatives from each company were sent with the goal of making it easier to connect external devices to PCs, while addressing the constraints and usability issues of current methods. One of the team members working on this was Ajay Bhatt, who worked at Intel, which then produced the first USB ICs in 1995. This original specification had a standard data rate of 1.5 MBit/s, up to 12 Mbit. /s, and was supported by Microsoft Windows '95 Service pack 2, but it took a few years before USB began to become standardized.
In September 1998, USB 1.1 was released, which had fewer time and power constraints and was adopted much faster, and was described by Microsoft as the "legacy free PC". All iMac G3s also support USB 1.1. Of course, given the still somewhat limited speed, USB 1.1 wasn't ideal for external storage devices, even with file sizes that were typically much smaller compared to today's behemoths. For Apple users this didn't really matter, they had Firewire, but for everyone else, USB 2.0, released in April 2000, was the point where we caught up, offering a high-speed mode of 480 Mbit/ s. By now the ball was firmly rolling and PCs that may have had only one nominal USB port, began to have multiple ports on the front and back.
The legacy connections still persisted, but from about 2010 onwards, they largely disappeared. Since 2007, the USB battery charging version has been implemented and with the advent of USB 3.0 in 2008, offering up to 5 Gbit/s, pretty much the entire base has been covered. Which lands you in the USB-saturated world we currently know and love. For the most part. USB has definitely made things so much easier and more convenient, but I still crave the clutter of cables and connections from the 90s. Finding male-to-female adapters, sorting serial null-modem cables from standard ones, networking PCs with cables homemade to play Doom. It was splendid, luckily I can still have fun playing with old hardware.
The rest of us probably couldn't give a monkey.
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