Single board computers aren’t anything new infact they have existed since 1976 when the dyna-micro was released based on the Intel C8080A CPU.
Since then they have been used in many embedded applications from digital signage to satellite and aerospace applications, in 2012 the Raspberry Pi foundation released the Raspberry Pi Model B which redefined the SBC standard with many manufacturers producing boards based on the Raspberry Pi form factors and GPIO standard ever since but what was the prior standard?
Back in 1987 a company called Ampro released an SBC which would later define a standard known as PC/104 (or PC104) in 1992. In 1997 the PC/104-plus form factor was developed which included PCI and in 2008 the PC/104-Express was the final revision including a PCI-Express Bus.
The PC-104 is based on the IBM XT bus which includes 64 pins and the IBM AT bus which includes 40 pins hence the name PC/104.
The PC/104 pin out can be found here: http://www.interfacebus.com/Design_PC104_Pinout.html
The PC/104 standard is designed to be stack-able with different add on cards available.
The PC/104 standard includes 3 form factors:
- 3.550″ x 3.775″
- 5.75″ x 8″
- 6.5″ x 4.5″
All of the above standards are electrically and physically compatible with one another, the only difference is the physical board size although the mounting holes and ports align.
More history on the PC/104 can be found on Wikipedia here. Lets have a look at a PC/104 compatible board.
The HannStar EMC-3412
The HannStar EMC-3412 is a PC104 compatible SBC produced sometime between 2001 and 2005, the board features a PC133 SODIMM slot, a USB header, PS/2 connector, RS232 Male and RS232 Female, VGA Video, CF and IDE. A NSC Geode GX1S@300Mhz and a single Realtek 100Mb NIC.
Whilst I purchase this board brand new with 128MB of RAM I’ve struggled to find much information on the device. I decided to review it as if it was any other SBC.
I installed Debian 8 onto a 4GB Microdrive using Virtualbox with my BENFEI 4in1 USB USB-C to SD Micro SD MS CF Card Reader as the board does not boot from USB and I did not have a IDE optical drive to hand. Debian 8 is the final release of Debian to support i586 processors. The install ran smoothly and the board booted without issue from the MicroDrive fitted in its CF card slot.
The board is powered using a standard Molex 4 pin connector although it appears that it only uses the 5v pins. I created a makeshift adaptor to run this device off USB.
The CPU runs at 300MHz and has very few features, it is a x86 compatible i586 processor.
Power consumption isn’t as bad as I expected pulling only 1w at idle and 6w at full load.I measured the power consumption with my Keweisi USB Power meter and a custom cable.
I ran UnixBench to compare this to my other SBC’s and it Scored a total of 16! That’s 4x slower than even a Raspberry Pi Zero.
The Hannstar EMC-3412 was fun to play with and would likely make a great Retro Gaming machine although I can’t think of any real useful use cases for the board in 2021. I purchased this new on ebay and the seller still has a fair few for sale priced at £30 with make offer, I made a very low offer and it was accepted. If you’d like to try one out for yourself you can buy one here.
The PC/104 standard is still widely used in embedded computing with lots of manufacturers producing new boards with modern CPU’s however they are very expensive and designed for very specific applications.
If you would like to see more covered on retro SBC’s leave a comment below.