Usually, owners of old computers that are still working properly and performing their tasks have a hard time finding components to upgrade or repair the system. It’s not easy to buy DDR2 or DDR3 memory modules these days. Not to mention older systems that used memory in the form of 30-pin SIMM modules. However, this is not a problem if you know how to hold a soldering iron, as the YouTuber Bits und Bolts proved.
He set out to create SIMM memory modules for systems based on the Intel 80386 processor from commercially available components. This chip was introduced back in 1985, almost 40 years ago. To make the challenge not too easy, he decided to create memory modules of a gigantic (for those times) size – 16 MB. The standard during the 386DX era was 4 MB. After all, RAM modules were usually 1 MB in size. So, the plan was to install an incredible 64 MB of RAM in the system. He documented his success in this test in the form of a video tutorial on YouTube.
Currently, you can still buy 16 MB SIMM modules. However, they are expensive, usually already in use, and have not been tested reliably. There are also questions about how to ensure that you have FPM memory rather than EDO. The author of the video solved this problem by hacking the memory modules to allow them to switch between EDO and FPM modes.
Bits und Bolts started by researching the specifications and manuals for his 386 motherboard to see if it could boot with that much memory. It turned out that it could, but only if he filled four of the eight sockets on the board. That was quite a lot of memory, even two generations later, when the Pentium chip debuted.
After completing the project, the author successfully booted his 386 computer with 64 MB of RAM. To test this amount of memory with memtest, it took 10 hours to complete one test run.
In another video, Bits und Bolts shows the opening of Windows 3.1 and the RAM drive extension he created for it. The author provides links to the custom PCB boards needed for the memory, as well as the tools and materials he uses to assemble the modules. His next step will be to determine how much more additional memory he can fit into his 486 systems.
Source: tomshardware