Thread

Strange board on Mac 512k

· Hardware · 36 posts · Mar 22, 2010 — Mar 31, 2010 View original thread ↗

#31 Mon, 29 Mar 2010 - 20:30

There are close to 40 ICs on that board. An NTSC or PAL conversion board typically has three logic chips. There's a bank of eight pc74hct161p (MOSFETs?) and an unidentified bank of four similar looking ICs.

This is a very unusual board. The production values look fine to me, based on what was around in the 1980s. My guess is that it is some kind of multimedia output device like the Beck Chromatron that generated a colour signal from the MacPain pallete.

#32 Mon, 29 Mar 2010 - 21:19

74hct161

binary counter, counting is very important when fabricating a video signal from a computer

#33 Mon, 29 Mar 2010 - 22:16

I had a thought about this in the shower yesterday!

My buddies at Tekserve got their start in Macs by building the (Mac controlled) Directory Systems for the Rockefeller Center (yes the place with the ice rink!) Office Retail/Space in NYC. This might be a similar board for some kind of Video Based Display. In that case a Color Lookup Table would substitute for the, then unavailable, Color Macs/Toolbox routines. Sound and an external Graphics Output System, TTL or CGA, would make a world of sense. That would easily explain all the extra logic on board. Coupled with the RS-422 Connections, you could do a LOT with a Mac in any Graphics based Display, Signage, Directory, etc.

Dunno, that's just a WAG! :-/

#34 Tue, 30 Mar 2010 - 02:13

Sound and an external Graphics Output System, TTL or CGA, would make a world of sense

Why sound though? If it were specifically for an external graphics display, why not just take the sound off the Mac's own port (if you even needed it)?

And Charlieman, good to know you are still lurking around. :beige:

#35 Wed, 31 Mar 2010 - 18:25

Separate sync? Or just an alternative plug for the same video output?

#36 Wed, 31 Mar 2010 - 19:08

Touch Screen or button Interface? Multiple sound inputs/outputs? :?: