Notices by Tube🌞Time (tubetime@mastodon.social), page 9

New release: the Goodgreat DS3, the Apple II sampler card i reverse engineered from an album cover!

Download the design here: https://github.com/schlae/goodgreat-ds3

it's the first electronics flea market of the year here in silicon valley! (electronicsfleamarket.com)

(3)

@ke8smq i figured as much. the part number on this IBM cleaning fluid looks too new to be used on the equipment i was looking at (late 70s era, not 80s or 90s)

(2)

a story in three parts (1)

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

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

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

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

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

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.

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

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

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."

some great pixel art from my brother. this was displayed with a genuine IBM CGA card (really!)

whatever you do, don't misapply this capacitor.

did you know that some early radio transmitters were electromechanical? i didn’t either! https://mastodon.social/@tubetime/110970146022678448

remember that Thinkpad 700 from earlier? i started a massive project to build a replacement solid state hard drive for it. the drives were not IDE; they were a special IBM interface called DBA-ESDI. https://mastodon.social/@tubetime/110783604330499249

some old DOS utilities had a graphical mouse cursor in text mode! i’ve investigated how they did it. https://mastodon.social/@tubetime/111123817309591559