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Tube🌞Time

got another weird chip. SCM43527L. no idea...
24 February at 23:07 | Open on mastodon.social
17 comments
Tube🌞Time

there's something weird about the markings on the bottom of the chip
24 February at 23:08 | Open on mastodon.social
Robert Petersen :pacman:
Tube🌞Time

got a better die photo. i think i know what this chip is.
26 February at 2:10 | Open on mastodon.social
Tube🌞Time

the cells are way too simple to be SRAM or RAM. i think this is a ROM.
26 February at 2:11 | Open on mastodon.social
Tube🌞Time

the array is 32x32, and there seem to be four outputs at the bottom of the array. that would make this a 256x4 ROM.
26 February at 2:12 | Open on mastodon.social
Tube🌞Time

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.
26 February at 2:13 | Open on mastodon.social
Tube🌞Time

pins 3, 4, 5, and 6 appear to have large output driver transistors.
26 February at 2:15 | Open on mastodon.social
Tube🌞Time

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
Tube🌞Time

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
PhDog 🇮🇪
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
Tube🌞Time

@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
djb_rh

@tubetime The case looked like ROM of the day, too.

26 February at 2:49 | Open on mastodon.social
/dev/rdsk/c0t0d0s2

@tubetime this is close to @NanoRaptor level shitposting too

25 February at 0:36 | Open on aus.social
chuckbenz

@tubetime Moto undoubtably made custom chips for specific customers and wouldn’t have published docs on them. Perhaps there might be public info on part number ranges that they used for customer chips, but perhaps not. Could be interesting to reverse engineer.

25 February at 1:43 | Open on techhub.social
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