Before VMWare, VirtualBox and other virtualization/emulator environments, hardware emulators were required if you wanted to run other computing environments on a different piece of hardware.

Hardware Emulators
Atari hardware running Macintosh software (Spectre GCR)
Macintosh hardware running PC software (Orange PC)

Today, there are developers who are creating new hardware emulators (implementations) of older hardware such as the Amiga 500 (the Minimig).

Spectre GCR - The Spectre GCR was a hardware add-on to the Atari ST computers that plugged into the cartridge port.  It essentially turned the Atari ST into an Apple Macintosh computer.  The Spectre GCR required the owner to purchase a set of official Apple Macintosh 128K ROMs and the Macintosh Operating System 6.0.8 disks. This avoided any legal issues of copying/pirating Apple's software. The emulator runs best with a high-resolution monochrome monitor, such as Atari's own SM124, but will run on colour displays by either displaying a user-selectable half of the Macintosh screen, or missing out alternate lines to fit the lower resolution colour display. The Spectre GCR plugged into the cartridge slot, and modified the frequency of the data to/from the single-speed floppy drive of the Atari ST, thus allowing it to read Macintosh GCR format discs which required a multi-speed floppy drive. [source: http://en.wikipedia.org/wiki/Spectre_GCR]

http://www.oocities.org/clu-da-bard/
http://dev-docs.atariforge.org/files/Spectre_GCR_Manual.pdf

Orange PC - PCI card (5V 32-bit slot) that allows you to run Windows 95/97 and DOS on PCI equipped Macs. This is a model 540 which has an Intel P1 onboard running at 166 MHz. 

http://en.wikipedia.org/wiki/Orange_Micro
http://www.vintagemacworld.com/omweb/orangepcfaqs.html#Anchor-Can-42424
http://en.wikipedia.org/wiki/Peripheral_Component_Interconnect 
http://www.vintagemacworld.com/O386.html
http://www.vintagemacworld.com/omweb/HowToUpgrade34.html

SUN Penguin PCI - SunPCi is a series of Single Board Computers with a PCI connector that adds hardware which enables Sun workstations to act as an 'PC compatible' computer. It includes an x86 processor, RAM, expansion ports, and an onboard graphics controller, allowing complete x86 operating environments on Sun Workstations. 
[source: http://en.wikipedia.org/wiki/SunPCi]


SunPCi (400 MHz p/n 375-0095) (not supported on Solaris 9/10)

Minimig - the first hardware emulator of an Amiga 500 system based on Dennis van Weeren's open source project and produced by ACube Systems in Italy.  The original Amiga chipset (OCS and ECS) is re-implemented in FPGA.  Furthermore, thanks to the onboard 68000 cpu, the same used on the original machine. the emulation of the original hardware is accurate and it is possible to run a wide number of games and applications simply copying the ADF files (they are images of the original floppy disks) on a standard SD card. Standard PS2 keyboard and mouse (commonly used on PCs) are supported as well as original Amiga mouse and joystick.

The Minimig is available in the following configurations:

• Fully assembled board with 2 MB RAM and 1 GB SD Card
• Fully assembled board with 4 MB RAM and 1 GB SD Card
• Universal PSU (110 or 220V)

source: http://www.acube-systems.biz/index.php?page=hardware&pid=3

One of the interesting things is looking at the evolution of mobile computing in terms of hand-held units.

• Pocket Computers (TRS80, Sharp, Panasonic)
• PalmTops (Atari Portfolio, HP200X)
• Personal Digital Assistants (PDA) - (Sharp, Compaq, Dell)
• Tablets (iPad, HP TouchPad, Android)
• SmartPhones (iPhone, Samsung Galaxy)

Pocket Computers
A pocket computer is a small calculator-sized handheld programmable computer.  This specific category of computers existed primarily in the 1980s. Manufacturers included Casio, Hewlett-Packard, Sharp, Tandy/Radio Shack (Selling Casio and Sharp models under their own TRS line) and many more. The programming language was usually BASIC, but some devices offered alternatives. For example the Casio PB-2000 could be programmed in Assembly, BASIC, C, and Lisp.[1] An important feature of pocket computers was that all programming languages were available for the device itself, not downloaded from a cross-compiler on a larger computer. 
[source: http://en.wikipedia.org/wiki/Pocket_computer]

Collection includes:

• TSR80 Pocket Computer Model: PC-4
• TSR80 Pocket Computer Model: PC-2 + printer interface

PalmTops/Handheld PC
A handheld PC, or H/PC for short, is a computer built around a form factor which is smaller than any standard laptop computer. It is sometimes referred to as a palmtop. The first hand-held device compatible with desktop IBM personal computers of the time was the Atari Portfolio of 1989. Other early models were the Poqet PC of 1989 and the Hewlett Packard HP 95LX of 1991. Other DOS-compatible hand-held computers also existed.
 [source: http://en.wikipedia.org/wiki/Palmtop_computer]

Collection includes:

• Atari Portfolio

Personal Digital Assistants (PDA) 
A personal digital assistant (PDA), also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. PDAs are largely considered obsolete with the widespread adoption of smartphones. A PDA has an electronic visual display, enabling it to include a web browser, all current models also have audio capabilities enabling use as a portable media player, and also enabling most of them to be used as mobile phones. Most PDAs can access the Internet, intranets or extranets via Wi-Fi or Wireless Wide Area Networks. Most PDAs employ touchscreen technology.  The first PDA was released in 1984 by Psion, the Organizer. Followed by Psion's Series 3, in 1991, which began to resemble the more familiar PDA style. It also had a full keyboard. The term PDA was first used on January 7, 1992 by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. [source: http://en.wikipedia.org/wiki/Personal_digital_assistant]

Collection includes:

• Apple Newton
• Sharp Zaurus
• Handspring
• Dell Axim

Tablets
A tablet computer, or simply tablet, is a mobile computer with display, circuitry and battery in a single unit. Tablets are equipped with sensors, including cameras, microphone, accelerometer and touchscreen, with finger or stylus gestures replacing computer mouse and keyboard. Tablets may include physical buttons, e.g., to control basic features such as speaker volume and power and ports for network communications and to charge the battery. An on-screen, pop-up virtual keyboard is usually used for typing. Tablets are typically larger than smart phones or personal digital assistants at 7 inches (18 cm) or larger, measured diagonally.  Hybrids that include detachable keyboards have been sold since the mid-1990s. Convertible touchscreen notebook computers have an integrated keyboard that can be hidden by a swivel or slide joint. Booklet tablets have dual-touchscreens and can be used as a notebook by displaying a virtual keyboard on one of the displays.
Collection includes:

• Android
• HP TouchPad

SmartPhones
A smartphone (or smart phone) is a mobile phone with more advanced computing capability and connectivity than basic feature phones.  Early smartphones typically combined the features of a mobile phone with those of another popular consumer device, such as a personal digital assistant (PDA), a media player, a digital camera, and/or a GPS navigation unit. Later smartphones include all of those plus the features of a touchscreen computer, including web browsing, Wi-Fi, and 3rd-party apps.
[source: http://en.wikipedia.org/wiki/Smartphone]




Collection includes:

• Apple iPhone 3
• Samsung Galaxy 3

Forest Ranger (2014) - ForestRanger is an application for visualizing large amount of Forest Plots generated from cross sectional surveys (i.e. Canadian Community Health Survey - CCHS).  The Forest Plot(s) report on the association between outcome and exposure variables (i.e. Stroke versus Hypertension adjusted by sex and age) broken down by survey year (i.e. 2008, 2007, 2006, 2005, etc.).  For a chronic disease series of reports there could be 20 variables reported on which would correspond to approximately 400 charts.  ForestRanger allows a researcher to quickly see which associations are increasing or decreasing or have the greatest Odds Ratios (OR) of the associations.  The researcher can then click on the chart of interest and the larger report appears on the right hand side.  ForestRanger can be used for visualizing any directory of PDFs.