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1. Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:23 JST Tube🌞Time

   in reply to

   looks like a perfect match to the MCM14524! unfortunately it is a mask ROM: "This device is ordered as a factory special with its unique pattern specified by the user."

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:23 JST Tube🌞Time

     in reply to

     how fun, you can specify the memory contents by mailing them four punch cards.

   • Foone🏳️‍⚧️ (foone@digipres.club)'s status on Monday, 26-Feb-2024 12:14:23 JST Foone🏳️‍⚧️

     in reply to

     @tubetime I think Fujitsu (or maybe it was Toshiba?) was later accepting 8mm backup tapes. Handy for the bigger ROMs

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:24 JST Tube🌞Time

     in reply to

     the array is 32x32, and there seem to be four outputs at the bottom of the array. that would make this a 256x4 ROM.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:24 JST Tube🌞Time

     in reply to

     pin 9 (and a bunch of others) are inputs. they go through a series resistor, a diode clamp (not visible here) and into a double set of inverters. this creates a buffered version of the input and an inverted version.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:24 JST Tube🌞Time

     in reply to

     pins 3, 4, 5, and 6 appear to have large output driver transistors.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:25 JST Tube🌞Time

     in reply to

     there's something weird about the markings on the bottom of the chip

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:25 JST Tube🌞Time

     in reply to

     got a better die photo. i think i know what this chip is.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:25 JST Tube🌞Time

     in reply to

     the cells are way too simple to be SRAM or RAM. i think this is a ROM.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Monday, 26-Feb-2024 12:14:26 JST Tube🌞Time

     got another weird chip. SCM43527L. no idea...