pin 9 (and a bunch of others) are inputs. they go through... | Tube🌞Time

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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.

Like 26 February at 2:13 | Open on mastodon.social

8 comments

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

26 February at 2:15 | Open on mastodon.social

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."

26 February at 2:19 | Open on mastodon.social

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

26 February at 2:21 | Open on mastodon.social

Foone🏳️‍⚧️

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

26 February at 3:12 | Open on digipres.club

cute!

26 February at 3:22 | Open on mastodon.social

waldi

@tubetime I immediately thought about mask rom. But I thought they changed just the metal layer, and I did not see any difference between cells.

26 February at 10:21 | Open on chaos.social

@waldi this is most likely a diffusion ROM so it would be difficult to see

26 February at 14:55 | Open on mastodon.social

Dustin

@tubetime I learned about factory ROMs but I’ve never used one. Very cool!

26 February at 3:17 | Open on geekdom.social