The Difference Between

A nickel-metal hydride battery, abbreviated NiMH, is a type of rechargeable battery similar to a nickel-cadmium (NiCd) battery but using a hydrogen-absorbing alloy for the negative electrode instead of cadmium. As in NiCd batteries, the positive electrode is nickel oxyhydroxide (NiOOH).

A NiMH battery can have two to three times the capacity of an equivalent size NiCd. However, compared to the lithium-ion battery, the volumetric energy density is lower and self-discharge is higher.

Common AA batteries (penlight-size) have nominal charge capacities (C) ranging from 1100 mA·h to 2700 mA·h at 1.2 V, usually measured at a discharge rate of 0.2×C per hour. Useful discharge capacity is a decreasing function of the discharge rate, but up to a rate of around 1×C (full discharge in one hour), it does not differ significantly from the nominal capacity.

The specific energy density for NiMH material is approximately 70 W·h/kg (250 kJ/kg), with a volumetric energy density of about 300 W·h/L (360 MJ/m³).

It is common to refer to most NiMH products as Batteries, even though the word Battery refers to the grouping of multiple cells. As a result sizes AA, AAA, C and D are technically Cells while the 9V size is a real battery.

A "serial printer" is a printer that use one cable that send "1" or "0" after one another to be understood as a character by the recipient device. The most common serial interface is "RS232" which may be used to control a fleet of devices, also printers. Because of obvious speed issues, to transfer a huge picture on an RS232 would take hours, the modern printers cannot use this interface for that, so instead, they use the "parallel" or "Line Printer" interface - where multiple wires send signals to the printer at once - as they used to in old days to the line printers.

On an old PC, you have the serial interface, RS232, on the "COM" port that you also used to attach the mouse to, while the Line Printer or "parallel" interface is the broad "LPR" connector used for printers and scanners and tape stations before USB was invented.

The question is "fish and fowl"...

The line printer is a specific type of printer where the letters spun around using chains and was halted to bring the correct imprint - 132 characters in one shot.

This could in theory only use a serial interface, it needed a parallel interface. The serial printer was one made with a buffer of many lines, to compensate for the low speed on the single wire (typically max 9600 bits per second). You may for instance drop the transfer of blank characters at the end of the line - most lines are less than 132 characters. There are other serial interfaces for shorter cables and higher speed. I remember just the Diablo printer (by Xerox) as capable of using the serial port, but expect that any printer could use it, also line printers. The serial interface could work for about 100 feet, while a parallel one less than 10. With the serial interface the printer could be away from the server, while the line printer had to be close to the server. With "Current loop" - a variant of RS232, where the signals travels on a live line, this could be extended at least 300 feet, and speed up to 64K bit per second - half of this was typical.

JPG and JPEG both stand both for an image format proposed and supported by the Joint Photographic Experts Group. The two terms have the same meaning and are interchangeable.

Both JPEG and JPG are bitmap compression formats for picture and image files with compression ratios ranging from 10:1 to 20:1. In fact, JPG and JPEG file formats are identical.

Older DOS-based computers were designed to handle a maximum "3-character file extension" which is why JPG was attributed to compressed image files. Newer Operating systems allow for longer file extensions as evidenced by .html. Accordingly, the JPG file extension was upgraded to the JPEG file extension which is the true acronym for Joint Photographic Experts Group.

A digital computer processes discrete data, an analog computer processes continuous data.

• Discrete data (integers, character codes, boolean values, encoded floating point numbers, etc.) represent information with sharp discontinuities between represented values. Any data value not exactly encoded must be approximated by one of the nearest encoded values. Operations on discrete values are more reliable and consistent, but usually slower with identical technologies.
• Continuous data (voltages, currents, fluid pressure, fluid flow, shaft position, shaft rotation rate, etc.) represent information by analogy. All data values (within the limits of the machine) have an equivalent representation. Operations on continuous values are less reliable and less consistent, but usually faster with identical technologies.

Analog computers are typically harder to program: they are either designed for one special purpose with the program permanently built in, or they must be "rewired" to reprogram them.

Computers have changed a huge amount over a short period of time, but surprisingly there are a lot of things that are still exactly as they were decades ago. At the very core, computers still use processors, RAM, hard drives, and other components - all interacting with binary data and executing instructions in "Machine Code". However, beyond this, a huge amount has changed.

A long time ago, back in the 1960s, the very first "modern" computers didn't even use a monitor - a lot of computers utilised a "printer terminal" - so every command you entered would cause the result to be printed out, line by line, on paper. So, you could argue, having a screen is a big change over time for computing.

More recent changes include:

• The use of graphical user interfaces. We take for granted that we use a mouse to click on icons and menus on a screen with Windows and a desktop - but this wasn't always the case. For a long time, computers used a "Command Line Interface" - which you can still see today by opening a command prompt on a Windows PC, or a Terminal on a Mac. (Or if you're using Linux, you're almost certainly already familiar with a terminal). Here, users would type commands to tell the computer what to do - so, opening a folder called "Games" on your hard drive would mean you'd have to type something like:

  C:\>cd C:\games

  rather than just clicking on a folder icon.

• The amount of memory and speed of operation has increased by staggering amounts. Personally, I owned a computer in 1993 which was an ICL 286 workstation. It had an 8MB hard drive, and a processor that ran at 12 megahertz. Today, most processors run with multiple "cores", at 3 or 4 gigahertz - over a thousand times faster - and use terabyte hard drives (that's over a million times larger than a megabyte).
• Easily, though, the biggest change to computing has been the internet. Today, it's almost unthinkable of using a computer which is not connected to the net - for downloading files, sending emails, even asking questions on this site. This certainly wasn't always the way, though. The internet and the World Wide Web really started becoming popular in the early 90s - prior to this, computers would at most either be networked to each other locally, or dial in to just one service at a time, using services like "Telnet". If you were to travel back in time to the 1980s and show the average computer user then a computer from today, the internet would easily be the most staggering thing for them to see. Most other advances like high resolution LCD screens or bigger hard drives would seem like logical advances - but the internet was truly revolutionary from a computing perspective.