
The Texas Instruments TMX 1795: the first, forgotten microprocessor - dezgeg
http://www.righto.com/2015/05/the-texas-instruments-tmx-1795-first.html
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MagerValp
It's fascinating how many great stories there are from this wild west period
of the computer industry, thanks for a great writeup.

I have to pick a nit with footnote 10 though, "There's no need for a processor
accessing bits in parallel to be little endian" – there is when your data bus
is narrower than the address bus, such as an 8-bit CPU performing indexed or
relative 16-bit addressing. The simple pipelining of the little endian 6502
allows it to calculate the lower half of the target address while it fetches
the upper half from memory, saving a cycle compared to the big endian 6800.

~~~
tr352
Also, wouldn't little-endianness generally benefit 16 bit arithmetic
operations performed on 8 bit ALUs? Because (correct me if I'm wrong) a carry
flag always carries over from LSB to MSB, processing the LSB before the MSB
allows you to implement the carry mechanism more efficiently.

~~~
MagerValp
Yes, though few 8-bit CPUs supported 16-bit arithmetic. Most required two
8-bit operations with carry instead, an din that case there's no difference
between little and big endianness - in both cases the LSB has to be calculated
first.

The big endian 6809 supports 16-bit arithmetic, and is indeed punished for it:
16-bit ADD and SUB costs an extra cycle compared to a little endian design.

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brink2death
[https://lh3.googleusercontent.com/-R1jlPIYh-
nU/VUlaRlv9DnI/A...](https://lh3.googleusercontent.com/-R1jlPIYh-
nU/VUlaRlv9DnI/AAAAAAAAm6g/9vPQCCV5rN8/w300/fourphase-trial-demo.jpg)

Are those SNES cartridges?

~~~
kens
After carefully studying pictures of SNES cartridges, I think you're right.
That's pretty funny that Boysel used game cartridges when creating the demo
system for a patent lawsuit.

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aninteger
There's another TI processor that never really took off despite its usage in
arcade consoles at the time. The TMS340
[http://en.m.wikipedia.org/wiki/TMS34010](http://en.m.wikipedia.org/wiki/TMS34010))
series. 32bit in 1987. I assume it was just out of the price range of 8bit and
16bit machines. It was used in Mortal Kombat and NBA Jam games I believe.

~~~
karmakaze
I remember those (coincidentally 68020/2) back when I was working at Eicon's
graphics group (now Eicon Networks). Ended up just using M68Ks with blitters
for PostScript and HP PCL interpreters. In the end the HP version even lost
the blitter chip and I had to write bitblt.s

~~~
kjs3
How did you implement your blitter?

~~~
karmakaze
I can't remember all the details now. The main interpreter was MS C with
CodeView in text mode was awesome. The routines were 68k assembly with pixel
write modes, optimized character blt, and there was a scale-up routine. The
only reason the sw implementation came close to hw was that the hw had quite a
bit of setup which is quite a bit of overhead for small patterns which were
typical (e.g. patterned horizontal rules).

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stefantalpalaru
> Some people consider the Datapoint 2200 the first personal computer as it
> came out years before systems such as the Apple II or even the Altair.

Programma 101 was being made and sold five years before Datapoint 2200:
[http://en.wikipedia.org/wiki/Programma_101](http://en.wikipedia.org/wiki/Programma_101)

~~~
agumonkey
Funny you mention Olivetti, I recently learned they were huge in those days.
Very fine design and 'better world' goals, very similar to Apple today.

trivia: it seems Olivetti was forced out of the Personal Computer business by
bad financial games from
[http://en.wikipedia.org/wiki/Carlo_De_Benedetti](http://en.wikipedia.org/wiki/Carlo_De_Benedetti)
cutting funds at a bad time.

~~~
Turing_Machine
I think every typewriter/office machine company tried their hand at computers
at some point. Royal McBee, Burroughs, Smith Corona (I don't think they did
full-blown computers, but they did do some dedicated word processors),
Remington Rand...

~~~
agumonkey
That was quite natural. Mechanical, electro-mechanical, mostly electronic.

~~~
Turing_Machine
Sure. The interesting question is why, out of all the office machine companies
that tried it, only IBM managed to pull it off.

~~~
kens
I think that gives the wrong impression, that office machine companies tried
making computers and failed. Remington Rand, for instance, was IBM's principal
rival in the 1950's, selling the UNIVAC. Olivetti had transistorized
mainframes before IBM. I think the interesting question is why IBM survived
while the rest didn't. My highly oversimplified answer would be the IBM 360
crushed them.

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Shivetya
the size difference and design technique between Intel and TI is telling. Even
though they are both of the same generation of chip Intel was just years ahead
in efficiency. The TI almost looks like a "will this work" or "that will do"
type design.

~~~
hga
Yeah, and the vastly greater size fed directly into it not being commercially
viable because of massively lower yield, all things being equal.

Add an unrealistic requirement for ultra clean power, and the thesis of the
article is quite debatable; this chip "worked in the lab" but was not viable
outside of it. Perhaps a good learning experience for TI, but hard to see more
than that.

~~~
agumonkey
Interesting facts about realism. Being first is very relative.

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nsxwolf
The pictured magazine article has a really modern layout for something written
in 1971.

~~~
EazyC
I was very surprised at that exact same thing as well. I thought I was the
only one. I really thought for a second that it was some magazine from the 90s
or even early 00s.

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FullyFunctional
My takeaway from this is that the author clearly documented the AL1 as the
worlds first microprocessor. The arguments against are artificial; it doesn't
matter that this wasn't the intended configuration nor that one essentially
had to program it in microcode. The microcode ROM is nothing more than a
compression technology which doesn't render it a more capable.

All that said, it's all arbitrary and the 4004 is the first _successful_
microprocessor. (I personally find it a more interesting question which
alternative architectures could have been produced given the technology and
constraints of the 4004 and 8080).

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oldpond
So, can anyone make an open hardware version of this chip? Have the patents
run out? It's been 45 years, and I understand they only last 25 years. A side
question would be which CPU architectures are openly available now that are
capable of running a modern Linux distro?

~~~
wtallis
The patent situation is such that one could manufacture a 32-bit x86 processor
without the various SIMD and virtualization extensions and not have to worry
about patents on the abstract architecture. Implementation techniques up to
and almost including the Pentium Pro (November 1995) would likewise be safe
from patent threats. However, semiconductors get explicit treatment under
copyright law
([http://copyright.gov/title17/92chap9.html](http://copyright.gov/title17/92chap9.html)),
so you have to do your own layout until such time as copyrights start expiring
again.

