Lo-tech EMS 2MB


In stock (can be backordered)

SKU: TELTEMS2MB Category: Tags: , , , ,


EMS Memory was designed to overcome the memory limitations of the original IBM XT.  The original architecture of the IBM XT has 20 address lines which gives a maximum memory space of 1MB.  The top 384k is typically reserved for BIOS, leaving the lower 640k available for applications.  In 1981, this seemed to be an obscene amount of memory.  As time went on, this was not enough, but what to do when you have a hard limit on the amount of RAM you can address?  The answer was EMS memory, co-developed by Intel, Microsoft & Lotus.  While this was a nice solution, you must have an application which is aware of how to use type of RAM.  Lotus 1-2-3 was one of the first, but later Windows, and many games and apps would make use of EMS to speed up gameplay and load more information into memory at once.

This card should work in pretty much any machine with an ISA slot, but it will be much slower than using conventional RAM.  This is partially due to how EMS memory is accessed (it take more clock cycles to read / write) but also because this is an 8-bit board, so data access is limited to 8-bit.  If you have a 386 or 486 with a 8mb of RAM or more, we would recommend using EMM386.exe in DOS to create EMS memory space if you need it.  In old 80286 & XT machines, this is a great add-on for many games and applications.

This card requires a driver to run, which can be located below on the Lo-tech Wiki link.  When setting up the card, you will need to pick a Page Frame Address, as well as an IO port.  The LTEMM.EXE driver may appear to succeed, even if you set it up with a conflicting address.  There is a link at the bottom of the page titled “Lo-tech EMS Board Utility”.  Please download and run the utility to ensure you have a clean port and range setup.  We’ve run into this a few times, so it can take a little trial and error to get it right.  Our test Packard Bell PB500 likes port 0x26C and 0xD000 with a Lo-tech Compact Flash card set to 0xC800.

This card does not have a mounting tab, so please be careful to orient the card the proper direction in the system.  Plugging a card in backwards could damage the card, or your PC.  We test all of our assembled boards, but we do not guarantee compatibility nor are we responsible for any damage to your equipment.  Please treat this board, and your PC with as static-sensitive, and never install cards while the power is on.   We test all of our preassembled boards, so there may be a little wear on the teeth.  Non-assembled PCBs will not have this wear.

Lo-tech reference pages: wiki page and required LIM4 EMS driver (LTEMM.EXE).

You can download the driver and utility files here: 2MB-EMS-Files.zip

Additional information

Weight 2.1 oz
Dimensions 4 × .5 × 3.25 in