8 ms·
TROS: IBM mainframes stored microcode in transformers
- agumonkey 7y agoAs impressive as frightening.
- ddingus 7y agoWhat is the frightening part to you? Sincere question. I am just curious for perspective. I like old tech and am always interested in others general take on it.
- agumonkey 7y agoThe amount of ingenuity and complexity and also a bit of "wildness" factor
- ddingus 7y agoReminds me of pre digital music. Same things. Humans who knew their shit and who presented raw skill, acumen. Yeah. I get that. What if we are somehow forced to return? Some disaster or other. Will we still be those same quality humans?
- agumonkey 7y agoThere's a bit of that in the pre digital eras. Things were much more complex and strange. Before doing anything with electric systems you had to study sophisticated mathematics. Now you can just get along with some arithmetics.
- butterisgood 7y agoMore than meets the eye
- bitwize 7y agoI knew it! OS/360 was a decepticon plot all along!
- deelowe 7y agoHuh. Kind of similar to rope memory in function but packaged completely differently.
- jascii 7y agoThe article actually mentions that and compares the two: Rope memory has a higher storage density (important for a spacecraft) while mylar TRO is easier to change the programming (hole punch a stack of sheets vs threading a lot of wire through cores)
- pacaro 7y agoTFA also notes that the roles of the wires in the two types of memory is reversed
- paulsutter 7y agoCan anyone find the speed of this memory?
- kens 7y agoTROS had a cycle time of 625 nanoseconds with an access time of 240 nanoseconds including address decoding and delays through the sense amplifier.
- ddingus 7y agoMy Apple 2 has 100ns RAM. I am pretty sure slightly faster machines used 80ns. This old memory speed seems fairly respectable for the time.
- blattimwind 7y agoGPIB, a bus system from the mid 60s, requires a response time of <100 ns to a particular signal. That's one of the reasons why it's still practically impossible to implement in software only 50 years later.
- ddingus 7y agoAnd we hit that on tech of the era too. Damn cool.
- blattimwind 7y agoWe had discrete logic in the late 60s that achieved toggle rates of a couple hundred MHz (ECL), it was just kinda expensive and needed loads of power. It was (and afaik still is) however widely used in aerospace/military applications (high standing currents and low impedance transmission lines probably make for excellent radiation and interference immunity) and used to be common in high end high frequency test equipment (e.g. counter/timers, synthesizers). I've heard ECL was also very popular for implementing cryptographic devices due to its low noise / switching transients.
- AstroJetson 7y agoSo while we are in awe, there is some group of engineers that are going "hey grandkid, let me tell you about Mylar memory. They pushed the envelope back in the day. It would be nice if some of these articles would have names so we could go "wow Bob, that was some amazing engineering".
- wil421 7y agoWhat’s Mylar memory? Is it magnetic core memory?
- gopalv 7y agoThe article starts with "This unusual storage mechanism used a stack of Mylar sheets to hold 15,360 bits, equivalent to 1920 bytes."
- wil421 7y agoYes I know it even has a picture. My question is what is it?
- deleted 7y ago[deleted]
- chiph 7y agoIt's a sheet of Mylar that has had conductive traces deposited on it, forming wires. This means it can be bent to go around curves without the use of additional connectors. The interesting thing to me about the TROS sheets is that they were initially manufactured to be the same [0] but were programmed by punching out (cutting) the traces in places to zig-zag the current path either through a transformer loop or around it. Presumably there was a machine that positioned a punch to the correct position, based on coordinates from an input punch-card deck, before descending and cutting through the traces. [0] Note that there are two designs - one with the inputs on the left and one with the inputs on the right, to line up on the connector block to the diodes. Although it's possible it's the same design, just flipped before the punching step.
- aidenn0 7y agoJust a few years later, HP did 16 layer PCBs instead of the mylar tape and achieved ROM that was very dense and fast for its time[1]; though apparently yields were quite poor. 1: http://www.hp9825.com/html/the_hp_9100_rom.html http://www.hp9825.com/html/the_hp_9100_rom.html
- myself248 7y agoI've heard about program store sheets in the Bell System early electronic computers, but I'm not sure how they compare to this. Never have found a good explanation of how they worked, just a few of my older colleagues described a stack of "memory sheets" they'd swap when it was time to change the computer's programming.
- flyinghamster 7y agoThe #1 ESS telephone switch's processor used two types of memory. Ferrite sheets were used for read/write memory to store temporary data, in a manner similar to magnetic core memory, while twistor memory was used for rewritable but mostly read-only storage, to store the system programs. https://en.wikipedia.org/wiki/Twistor_memory https://en.wikipedia.org/wiki/Twistor_memory https://en.wikipedia.org/wiki/Number_One_Electronic_Switching_System https://en.wikipedia.org/wiki/Number_One_Electronic_Switchin...
- jcims 7y agoMy stepdad worked for AT&T back in the 70’s/80’s. He took us to his office one night and we saw an old ESS switch that had magnetic core memory. I just started programming at the time but remember it creeping me out for some reason. We also listened in on a random phone call and called a small restaurant in France to listen to the menu of the day.
- ddingus 7y agoOld tech is cool to me because so much of it was human scale. One can just see the parts. Love it.