today's project is to fix this old Seagate ST-412 hard drive. 10MB, full height, and really loud!
here's a problem: the positioner stepper seems to move around randomly on power up. it's supposed to wait until the rpm goes nominal before moving. could be an issue with one of the motor phases.
looks like the stepper is controlled from an MCU. but there's some electronics in between i should check.
here's an amazing thing! it is a 370 channel simulator. what is that, you ask? well, read on! 🧵
the System 370 was a series of IBM mainframes from the 1970s. it was the follow-on to the System 360.
you could connect a variety of peripherals to your System 370, including things like printers, disks, tapes, and so forth. except these peripherals were typically quite large, like this array of hard disks!
so this gif has been making the rounds, with the unhelpful title of "data cable on a computer from 1945". but what computer? what sort of data? let's find out.🧵
the gif is from this YouTube video, an introduction to the ENIAC, where they interview some folks and show off the pieces of the ENIAC on display at the University of Pennsylvania.
but where to start? it turns out we still have the operating manual for the ENIAC!