
68 Katy – 68000 Linux on a Solderless Breadboard - peter_d_sherman
http://www.bigmessowires.com/2014/11/17/68-katy-68000-linux-on-a-solderless-breadboard
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tunesmith
Followups since this was posted in November:
[http://www.bigmessowires.com/category/68katy/](http://www.bigmessowires.com/category/68katy/)

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CamperBob2
God watches out for drunks, fools, and people who build multi-MHz logic
circuits on solderless breadboards. :-P

From a signal-integrity perspective, he should _not_ be able to get away with
that.

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Animats
He can't. _" My 68008 runs at 2 MHz (it was unstable when tested at 4 MHz),
providing similar performance to a 1 MHz 68000."_ He had to de-rate the clock
speed of an 8MHz part to get it to run on that breadboard.

The 68000 line has a sad history. It came out in 1979, and for a while, it
looked like it was going to be the winning microprocessor. Intel didn't have a
32-bit entry for years later. But early attempts to build workstation machine
ran into problems. The 68000 had no matching MMU, and wouldn't work properly
with an MMU anyway - page fault state saving wasn't quite right. Machines with
external MMUs were built anyway, but great kludging was needed to get around
the design flaw. The Apple Lisa avoided using increment instructions, and
Apollo had two CPUs; one for the user and one for the kernel, with only one
running at a time.

That was fixed in the 68010, which came out in 1982. But by then, IBM had
picked the Intel 8088 for the IBM PC. Motorola didn't come out with the
MC68451 MMU until a few years later, and it was a slow, segment-oriented MMU.
So the Macintosh didn't have an MMU, and had a much weaker OS than the Lisa -
no process isolation, no paging, not even a real CPU dispatcher. The UNIX
workstation crowd (Apollo, Sun, HP, etc.) all developed their own MMUs for the
680x0 line.

If Motorola hadn't had those errors in the 68000 and had shipped an MMU
earlier, the history of computing could have been quite different.

~~~
jdswain
Looking back it does appear that Intel did nearly everything right, and their
competitors didn't. It did help a lot though getting the IBM PC business, and
due to that, aligning with Microsoft. If you look at the 68000 machines at the
time they all had flaws that prevented them from really taking off, often not
things that couldn't be corrected, but things that held them back. The Mac
didn't have a hard disk, or multitasking, or color. The Amiga would always be
constrained by the custom chips and that would be a problem long term, plus
Commodore wasn't investing enough in software. Atari had a good simple
product, and GEM wasn't too bad, but they didn't develop it further either.
And the workstation market was constrained, as said by the parent, by the lack
of a decent MMU solution. And then RISC came along too. In an alternative
universe maybe the 68000 machines could have joined forces around a common
unix platform and built a major market, but that didn't happen here.

~~~
kw71
What held back the 3b1? That's rarely mentioned in these parts, but it was a
fantastic machine from a company that had experience building real computers
(if even for its own use.)

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Animats
There were a lot of early UNIX workstation companies in the early 1980s. Three
Rivers, Apollo, HP, IBM, Apple, Sun, Sony, and AT&T all had 680x0-based
machines. All totally incompatible.

At the time, it looked like lower-cost versions of those were the future of
computing. But, as mentioned previously, Motorola was too slow getting the MMU
situation fixed, which meant that all those workstations had some homebrew MMU
that ran up the cost. Not until the 60030 in 1987 did Motorola offer an on-
chip MMU. Workstations in that era cost $10K - $20K in 1980s dollars. Even the
Apple Lisa was a $10K machine. Workstation prices didn't come down fast
enough. Meanwhile, people were learning how to get things done on the original
DOS PC, clones, and PC/AT, which had inferior technology but volume was
driving down the price.

We had UNIX on the desktop in the 1980s, but few could afford it.

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Narishma
Previous discussion:
[https://news.ycombinator.com/item?id=8622720](https://news.ycombinator.com/item?id=8622720)

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farmdve
This is amazing, as a newbie in electrical engineering and just recently
playing with my Arduino this is simply awesome!!

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source99
Reminds me of 18-545 at CMU. We did it with wire wrap though. Good times.

Congrats on being able to fit the kernel in 512K

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davelnewton
Reminds me of the old PT-68K board; loved that thing, and the 68K.

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biturd
Would mac os 9 apps compile and run on this system?

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ramgorur
when ls -l /bin is being typed, all the last modified dates are "Jan 01 1970"
why ?

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jacquesm
Because they are read as '0' and that's the start of the unix epoch.

