manchesterssem

3 Articles

Thanks For The Memories: Touring The Awesome Random Access Of Old

March 8, 2016 by 41 Comments

I was buying a new laptop the other day and had to make a choice between 4GB of memory and 8. I can remember how big a deal it was when a TRS-80 went from 4K (that’s .000004 GB, if you are counting) to 48K. Today just about all RAM (at least in PCs) is dynamic–it relies on tiny capacitors to hold a charge. The downside to that is that the RAM is unavailable sometimes while the capacitors get refreshed. The upside is you can inexpensively pack lots of bits into a small area. All of the common memory you plug into a PC motherboard–DDR, DDR2, SDRAM, RDRAM, and so on–are types of dynamic memory.

The other kind of common RAM you see is static. This is more or less an array of flip flops. They don’t require refreshing, but a static RAM cell is much larger than an equivalent bit of dynamic memory, so static memory is much less dense than dynamic. Static RAM lives in your PC, too, as cache memory where speed is important.

For now, at least, these two types of RAM technology dominate the market for fast random access read/write memory. Sure, there are a few new technologies that could gain wider usage. There’s also things like flash memory that are useful, but can’t displace regular RAM because of speed, durability, or complex write cycles. However, computers didn’t always use static and dynamic RAM. In fact, they are relatively newcomers to the scene. What did early computers use for fast read/write storage?

Continue reading “Thanks For The Memories: Touring The Awesome Random Access Of Old” →

BabyBaby: A 1948 Computer On An FPGA

January 6, 2016 by 11 Comments

The Manchester Baby seems simple today. A 32-bit machine with 32 words of storage. It wasn’t meant to be a computer, though, but a test bed for the new Williams tube storage device. However, in 1948, it executed stored programs at about 1,100 instructions per second. The success of the machine led to a series of computers at Manchester University and finally to the first commercially available computer, the Ferranti Mark I.

[Dave] is lucky enough to volunteer to demonstrate the Baby replica at Machester’s Museum of Science Industry. He wanted his own Baby, so he used a Xilinx FPGA board to build a replica Baby named BabyBaby. Although it runs at the same speed as the original, it is–mercifully–much smaller than the real machine.

Continue reading “BabyBaby: A 1948 Computer On An FPGA” →

World’s Oldest Computer Music Unveiled

June 17, 2008 by 5 Comments


Fans of music made with obsolete technology are in for a treat: recordings of a Ferranti Mark 1 computer playing Baa Baa Black Sheep and In the Mood were recently released, and they are thought to be the oldest recordings of computer generated music in existence.

The Ferranti Mark 1 is a commercial version of Manchester University’s SSEM computer (aka Baby), which preceded several more well known computers like UNIVAC and EDVAC. It was one of the first computers that didn’t require a great deal of hardware rewiring to perform different tasks, making it ideal for this sort of purpose. It is not known whether the program was written to play these songs only or for more diverse composition and playback, but the author, [Chris Strachey] was known to be a friend of the legendary [Alan Turing]. The recording was released as part of the Manchester SSEM’s 60th anniversary celebration.