Re: Motherboard chip descriptions?

[Benjamin Ketcham <bketcham@drizzle.com>]

Ernest <leucoplast@seanet.nospams.com> wrote:
> Does anyone know of a book or website that describes what each of the
> different ICs (74LS* chips) on the Apple II and clone motherboards do? I'm
> going to be starting a "compare and contrast" project between the Apple II+
> and my different clone motherboards, which often have some interesting
> differences. If I can figure out what each of the different chips are for,
> then I might be able to better understand why chips were added or removed on
> different boards. That's my hope anyway.
> 
> Thanks.
> 
> E.
> http://www.apple2clones.com

Another poster suggested googling for datasheets, and that's a good
suggestion, will probably work.  You might also find it useful to
go directly to the site of one or more known manufacturers of 7400
chips, such as Texas Instruments.  Either way, the PDF datasheets
are the definitive word.

However, the set of chips used in the Apple II was fairly small (and
slightly idiosyncratic!); ISTM a discussion of them here might be of
interest.  The Apple II was one of the first (and last) computers that
I felt I fully understood, at the chip level.  It made a great learning
platform for hardware engineering, as well as software.

Glancing at the schematic, here's a few that I see, along with
the partial info that I have:

74LS00    Quad NAND gate.
74LS02    Quad NOR gate.
74LS04    Hex inverter.
74LS08    Quad AND gate.
74LS11    Triple 3-input AND gate.
74LS20    Dual 4-input NAND gate.
74LS32    Quad OR gate.
74LS51
74LS74    Dual D flip flop.
74S86     Quad XOR gate.
74LS138   3-to-8 demultiplexer.
74LS139   Dual 2-to-4 demultiplexer.
74LS153   Dual 1-of-4 multiplexer.
74LS161   4-bit binary counter.
74166     8-bit parallel-load shift register.
74LS174   Hex D flip flop.
74S175    Quad D flip flop.
74LS194   4-bit universal shift register.
74S195    4-bit universal shift register.
74LS251   1-of-8 multiplexer.
74LS257   Quad 2-to-1 multiplexer.
74LS259   8-bit addressable latch.
74LS283

(555)     Timer.
(558)     Quad timer.
(741)     Op amp.
(2513)
(HT28)
(HT97)

Add/correct at will...

--Benjamin