homebrew computer - where to start?

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

thanks for your time!

best,
jake

 

[jm]

<racter@gmail.com> wrote in message
news:1125732804.697587.191090@f14g2000cwb.googlegroups.com...

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

thanks for your time!

best,
jake

I doubt you're talking something so basic as the once offered (perhaps still
is) Radio Shack computer for kids. It had a bunch of LEDs that flashed with
logic signals of sorts. Even further advanced but on same level as LEDs
flashing or whatever - was the SWTP computer. SWTP - South West Technical
Products. A box about the size of a bread box or so - with LEDs on the front
(or an LCD readout - can't quite recall which) and a bunch of switches on
the outside. In a subsequent model I believe they offered a keyboard or pad.
I'm now 48 and this was all when I was 16 or so, so memory is faint there.
That "would" take you back to the very basics. From there came the Tandy
computer which I believe you've had already, as well as the Vic and
Commodore models and the TI-99 and then Apples. Someone with a better memory
than mine can elaborate. The Vic and TI-99 were pretty basic if memory
serves me correct. Heathkit/Zenith also offered such a computer set up as I
believe you're looking for. Maybe you can find one on E-Bay. National Radio
Institute (NRI) did a computer something like this for their course in
computers. I seen one recently - unbuilt with books on E-Bay. Not sure what
it sold for. Lafayette Radio offered a similar version of the Radio Shack
deal.

jm

 

[Jonathan Kirwan]

On 3 Sep 2005 00:33:24 -0700, racter@gmail.com wrote:

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

What an easy life you've had! In my day, I had to build it up solder
joint by solder joint. 256 bytes of static RAM was all I could afford
on the board. Metal bat handle switches developed calluses on your
fingers. ASCII was entered with 7 switches and a push button -- those
keyboards were for the silver-spoon, fancy-pants rich boys. Used
an AM radio nearby to help debug the programs by listening to the
tones.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.

Hehe.

i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

Well, you are in great luck, to be honest. There are good books today
as well as cheap FPGA boards and free software you can use to lay out
your own cpu. You almost won't even need a soldering iron.

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

Try "Bebop BYTES Back: An Unconventional Guide to Computers" from
Doone Publications as a very good and very detailed introduction. For
an introduction to VHDL and Verilog, try "HDL Chip Design" by Douglas
Smith (who, last I heard, had moved from England to Alabama.) I'd
recommend looking on the web for FPGA boards -- there is BurchEd and
Xilinx and a variety of others making such boards. Some of them are
in the $50 to $100 range and very, very good. Make sure you get
software with them for writing VHDL or Verilog and where you can do
floorplanning, later on (not now), and the like.

I'd recommend starting out with a simple board that includes some
switches and some 7-segment LED displays. Try writing some VHDL code
to perform various simple functions, like binary addition. That will
get you started on some of the basic features of an ALU (and you won't
need to understand sequential logic in VHDL, yet.) Work on busing
data around, addressing and registers, etc. You can use the internal
RAM in the FPGA for your program and data memory.

Just get doing it. It's not hard to do something good enough to get
the basic ideas across and learn from. It is so much easier to do,
today!

Jon

 

[Michael Gray]

On 3 Sep 2005 00:33:24 -0700, racter@gmail.com wrote:

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

Build your own processor?
Are you sure?
How much time and money do you have?

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

thanks for your time!

best,
jake

 

[Rich Webb]

On 3 Sep 2005 00:33:24 -0700, racter@gmail.com wrote:

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

How far back (and why?)? You could start with Babbage's Difference
Engine, I suppose.

And then there's the IMSAI, still alive over at http://www.imsai.net/.
I always thought they looked very "techy" but ended up getting a
Digital Group Z-80 system instead. Blazing 4.5 MHz, 18 KB static RAM:
http://www.brouhaha.com/~eric/retrocomputing/the_digital_group/

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

What I'd really recommend is a quick course in Verilog or VHDL and an
inexpensive development board like this (there are others out there, of
course): http://www.digilentinc.com/info/S3BOARD.cfm.

--
Rich Webb Norfolk, VA

 

[petrus bitbyter]

<racter@gmail.com> schreef in bericht
news:1125732804.697587.191090@f14g2000cwb.googlegroups.com...

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

thanks for your time!

best,
jake

Well, Jake,

A starting point is a matter of choice. Some early calculating machines used
cogwheels and functioned pure mechanicaly. The first electronic computers
used electron tubes by the dozens and required more power then your mains
connection can provide. The first computer I worked on was build with
discrete transistors, ferrite cores and lots of wire all packed in five 19"
rack enclosures higher then a mans length. The first one I build for myself
has a Z80 processor on 4MHz, 2k of RAM and 2k of EPROM. The latter contained
a monitor program derived from the NASCOM. I build, also from scratch, a
separate I/O card for it containing a UART that communicated with a dumb
terminal. The next step was an I/O card that could write to - and read from
cassette tape. Still works when I hook up a PC running a terminal emulator.
At about the same time you could buy Apples or one of its clones. You could
buy an empty board and fill it with components. Some time later you could
buy empty PC- and peripheral boards to do the same. AFAIK the last computer
building that required soldering. These days you can assemble your own
machine even without a screwdriver. IMHO you can't go back but to the first
microprocessors like the 8085, Z80, 6800, 6502 and some others I don't know
well. Some stuff, like the Z80, is still available. Don't know about the
others. Nevertheless, I don't think this is the way to go. The old times
will not come back you know. I advise to look around in the world of
microcontrollers. They have processor, RAM, ROM and I/O in one package but
fiddling with the bits, assembler programming and even soldering are still
required. There is a wide range of them from six pins SOT-23 to forty and
more pins DIP all with eight bits processors. The latter at least as
powerfull as the old Z80 and its contemporaries. If you want more there are
much more powerfull sixteen bits micros available as well. You'll find more
info then you ever can read on the web but you still can do plenty of things
others have not done before.

petrus bitbyter

 

[Charles Jean]

On 3 Sep 2005 00:33:24 -0700, racter@gmail.com wrote:

hi,

i've been a dedicated computer nerd for about twelve years now. i
started with a cast-off tandy "laptop" that ran BASIC and have been
hacking ever since, through 386/486/pentium/etc.

now i find myself much more interested in computer systems that appear
historically before my introduction to computers, and i'd really like
to get to know these older computing methodologies more intimately.
i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

so where do i start? poking around on the internet, all i can seem to
find is vendors trying to sell "homebrew" computer parts which
basically involves piecing together readymade components.

i know that the definition of "computer" covers a pretty wide continuum
right now, but what i'm interested in building is just the basic
machine: an electronic device that runs programs, whether it has a
display, printer, or just an array of LEDs as its output.

maybe someone knows a book or something that covers this material.

thanks for your time!

best,
jake
___

Jake-
If you can stand starting at the microprocessor level, try getting
your hands on "Build Your Own Z80 Computer" by Steve Ciarcia, BYTE
Books, McGraw-Hill, circa 1981, ISBN 0-07-010962-1.

Sounds like it might be just what your 'e looking for.
Cheers!
Charlie

___
"Sic hoc legere scis nimium eruditionis habes."
(If you can read this, you're overeducated.)

 

[Jonathan Kirwan]

On Sat, 3 Sep 2005 20:10:11 +0200, "petrus bitbyter"
<pieterkraltlaatditweg@enditookhccnet.nl> wrote:

A starting point is a matter of choice. Some early calculating machines used
cogwheels and functioned pure mechanicaly. The first electronic computers
used electron tubes by the dozens and required more power then your mains
connection can provide. The first computer I worked on was build with
discrete transistors, ferrite cores and lots of wire all packed in five 19"
rack enclosures higher then a mans length. The first one I build for myself
has a Z80 processor on 4MHz, 2k of RAM and 2k of EPROM. The latter contained
a monitor program derived from the NASCOM. I build, also from scratch, a
separate I/O card for it containing a UART that communicated with a dumb
terminal. The next step was an I/O card that could write to - and read from
cassette tape. Still works when I hook up a PC running a terminal emulator.

My first build-up was the Altair 8800 from a kit of parts. Years
before the Z80 was available. I remember looking with envy at the
8085 when it finally came out, because it had been so simplified from
the complex clocking monster that the 8080 was. And that was before
the Z80. The Z80 was so simple to design a board for. Nice!

At about the same time you could buy Apples or one of its clones. You could
buy an empty board and fill it with components. Some time later you could
buy empty PC- and peripheral boards to do the same. AFAIK the last computer
building that required soldering. These days you can assemble your own
machine even without a screwdriver. IMHO you can't go back but to the first
microprocessors like the 8085, Z80, 6800, 6502 and some others I don't know
well. Some stuff, like the Z80, is still available. Don't know about the
others.

Well, I've some 65SC02's laying around. And I'm sure I could find an
8080A and a clocking chip for it, if I looked.

Nevertheless, I don't think this is the way to go. The old times
will not come back you know. I advise to look around in the world of
microcontrollers. They have processor, RAM, ROM and I/O in one package but
fiddling with the bits, assembler programming and even soldering are still
required. There is a wide range of them from six pins SOT-23 to forty and
more pins DIP all with eight bits processors. The latter at least as
powerfull as the old Z80 and its contemporaries. If you want more there are
much more powerfull sixteen bits micros available as well. You'll find more
info then you ever can read on the web but you still can do plenty of things
others have not done before.

The only problem I have with your answer to the OP is that the OP
specifically asked this:

i'd like to try to build a computer from scratch - build my own
processor, etc. - to gain a greater familiarity with the underlying
technology.

It was the 'build my own processor' part of the above phrase that
really sounded to me like asking about how to design an ALU with
latched input paths and output, access to registers for latching, a
memory address latch, tri-state buffers on a common internal bus, etc.
I could have been wrong, though.

But that is a great deal of fun to learn about and do -- especially in
this day of cheap FPGA boards from a variety of sources in attractive
variations on a theme. It's almost dead simple to get started now
writing VHDL and getting a simple cpu up and going, entirely of your
own making. You don't even have to worry much about routing and floor
planning, as the tools will do a uniformly lousy job automatically but
one that still gets something working for you. And with the huge
resources available on these chips today, who cares if it all gets
ruthlessly squandered by the planner while you are learning VHDL?

It will be interesting to see if the OP is really more about learning
the internal basics of how a cpu works inside or more about learning
the larger picture of a cpu-memory-i/o system. There are so many
choices now that can teach at almost any level of interest -- from
internal cpu design all the way up to pasting down one-chip-wonders
that include all the I/O, code space, data space, and cpu processing
power and leave very little left to learn about.

Jon

 

[Michael Black]

Charles Jean (alchemcj@earthlink.net) writes:

If you can stand starting at the microprocessor level, try getting
your hands on "Build Your Own Z80 Computer" by Steve Ciarcia, BYTE
Books, McGraw-Hill, circa 1981, ISBN 0-07-010962-1.

Sounds like it might be just what your 'e looking for.
Cheers!
Charlie

I've never looked closely at the book, but my impression was that it
was to build a working system, circa whatever year it came out.

No matter how fancy a system was back then, it's going to be nothing
compared to what you can find in the garbage today. Thus I think
there's little reason to build a computer to that extent.

I think there's still plenty of reason to have something on the level
of the KIM-1, ie a calculator style keyboard and readout, a good monitor
that can single step etc, a cassette interface to save programs, and
some sort of general purpose I/O so you can play with things. There
were plenty of such single board computers back then, I use the KIM-1
as an example because I had one as my first computer.

But the single stepping meant you could run programs and see what
happened at every step. You could even just put in a line of code,
and check that out, really useful to getting a real feel for
what the op-codes were supposed to do. Since there was so little
in there, you didn't need to learn a whole lot of GUI stuff before
you tried out your simple program to add some numbers. The monitor
did have what you needed.

The general I/O meant that you could play with real things, like
hook some LEDs onto it and learn how to control them. Or have
inputs from something, to control the program.

These computers are of such a simple level that they are easy to build,
and you will get ample use of it (as opposed to trying to build a full
blown S-100 bus computer from 1976, which would have real limitations
today if you wanted to run applications). In some ways, it's even easier,
because whereas the KIM-1 needed 8 ICs to get 1K of memory, you can
scrounge up a static RAM that fills the address space that will draw
less current and require much less wiring. If you can live with
hooking it up to a terminal (ie your home computer running a terminal
emulator), then you can toss the readout and keyboard. Many of
those old boards allowed for hooking up a terminal to an RS-232 port,
though many of us didn't since the terminal cost more than the computer.
Likewise, one could use the home computer to store the programs, which
beats out a cassette interface in terms of speed and reliability.

ONe great project from the era was in Byte, though I can't remember the
year, or even a general idea. 1978 and 1980 somehow come to mind. Someone
wrote an article about bootstrapping an 8085. Jam a NOP onto the data
bus, so the processor advances the address bus while doing nothing. By
single stepping, this means you can load the RAM without any bootstrap
ROM. The input mechanism was a piece of circuit board that he'd carved
up with a hacksaw to make pads, and a "stylus" to connect a wire to
the needed pad. Some LEDs on the data bus. Not much else. Build
up the simple hardware, he just used wire to do it if I recall, and
you can start playing right away. None of that fussing with a bootstrap
ROM, but something you can infinitely play with it. Get some coding in,
and then add that monitor ROM. Or dig up the listing from an old single
board computer, and use that.

SOme years later, Byte put out a book about the 68000, and it had
an article (which I think had never run in Byte because I never
saw it elsewhere) using similar techniques to bootstrap the 68000.

Michael

 

[jm]

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in message
news:53tjh15kcc27010a1rdu1papv7118h0dnt@4ax.com...

On Sat, 3 Sep 2005 20:10:11 +0200, "petrus bitbyter"
pieterkraltlaatditweg@enditookhccnet.nl> wrote:


My first build-up was the Altair 8800 from a kit of parts. Years
before the Z80 was available. I remember looking with envy at the
8085 when it finally came out, because it had been so simplified from
the complex clocking monster that the 8080 was. And that was before
the Z80. The Z80 was so simple to design a board for. Nice!

At about the same time you could buy Apples or one of its clones. You
could
buy an empty board and fill it with components. Some time later you could
buy empty PC- and peripheral boards to do the same. AFAIK the last
computer
building that required soldering. These days you can assemble your own
machine even without a screwdriver. IMHO you can't go back but to the
first
microprocessors like the 8085, Z80, 6800, 6502 and some others I don't
know
well. Some stuff, like the Z80, is still available. Don't know about the
others.

Not "really" being wrapped up in computers back when the Z80, the Altair and
so on came out, I had forgotten about the KIM and so on. My question is -
trying to sort out my memory here - was the Altair 8800 sold be SWTP? OR a
different monster altogether? I DO recall the Altair now that it has been
mentioned - but may be getting it confused with South West Technical
Products - products.

jm

 

[Art]

May even run across some links to the Altair 8080 systems that preceeded
many "user Friendly" devices. These were once offeres in a kit of parts and
fair instruction manual. Basic, if my memory serves me, was the op-sys du
jour. Others may corect me if in error?? Item I had actually used Octal
Nixie Tubes for Hex Dec output which we manually decoded.
"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:dfd7rt$k6o$1@theodyn.ncf.ca...

Charles Jean (alchemcj@earthlink.net) writes:

If you can stand starting at the microprocessor level, try getting
your hands on "Build Your Own Z80 Computer" by Steve Ciarcia, BYTE
Books, McGraw-Hill, circa 1981, ISBN 0-07-010962-1.

Sounds like it might be just what your 'e looking for.
Cheers!
Charlie

I've never looked closely at the book, but my impression was that it
was to build a working system, circa whatever year it came out.

No matter how fancy a system was back then, it's going to be nothing
compared to what you can find in the garbage today. Thus I think
there's little reason to build a computer to that extent.

I think there's still plenty of reason to have something on the level
of the KIM-1, ie a calculator style keyboard and readout, a good monitor
that can single step etc, a cassette interface to save programs, and
some sort of general purpose I/O so you can play with things. There
were plenty of such single board computers back then, I use the KIM-1
as an example because I had one as my first computer.

But the single stepping meant you could run programs and see what
happened at every step. You could even just put in a line of code,
and check that out, really useful to getting a real feel for
what the op-codes were supposed to do. Since there was so little
in there, you didn't need to learn a whole lot of GUI stuff before
you tried out your simple program to add some numbers. The monitor
did have what you needed.

The general I/O meant that you could play with real things, like
hook some LEDs onto it and learn how to control them. Or have
inputs from something, to control the program.

These computers are of such a simple level that they are easy to build,
and you will get ample use of it (as opposed to trying to build a full
blown S-100 bus computer from 1976, which would have real limitations
today if you wanted to run applications). In some ways, it's even easier,
because whereas the KIM-1 needed 8 ICs to get 1K of memory, you can
scrounge up a static RAM that fills the address space that will draw
less current and require much less wiring. If you can live with
hooking it up to a terminal (ie your home computer running a terminal
emulator), then you can toss the readout and keyboard. Many of
those old boards allowed for hooking up a terminal to an RS-232 port,
though many of us didn't since the terminal cost more than the computer.
Likewise, one could use the home computer to store the programs, which
beats out a cassette interface in terms of speed and reliability.

ONe great project from the era was in Byte, though I can't remember the
year, or even a general idea. 1978 and 1980 somehow come to mind.
Someone
wrote an article about bootstrapping an 8085. Jam a NOP onto the data
bus, so the processor advances the address bus while doing nothing. By
single stepping, this means you can load the RAM without any bootstrap
ROM. The input mechanism was a piece of circuit board that he'd carved
up with a hacksaw to make pads, and a "stylus" to connect a wire to
the needed pad. Some LEDs on the data bus. Not much else. Build
up the simple hardware, he just used wire to do it if I recall, and
you can start playing right away. None of that fussing with a bootstrap
ROM, but something you can infinitely play with it. Get some coding in,
and then add that monitor ROM. Or dig up the listing from an old single
board computer, and use that.

SOme years later, Byte put out a book about the 68000, and it had
an article (which I think had never run in Byte because I never
saw it elsewhere) using similar techniques to bootstrap the 68000.

Michael

 

[Michael Black]

"jm" (nospam@garbagecan.com) writes:

Not "really" being wrapped up in computers back when the Z80, the Altair and
so on came out, I had forgotten about the KIM and so on. My question is -
trying to sort out my memory here - was the Altair 8800 sold be SWTP? OR a
different monster altogether? I DO recall the Altair now that it has been
mentioned - but may be getting it confused with South West Technical
Products - products.

jm


Tha Altair came first, being on the cover of Popular Electronics for

January 1975.

That's what set off the whole thing.

Of course, there was the Mark-8, an 8008-based computer that was on
the cover of Radio Electronics for August 1974, but while there was
interest in that, it somehow did not get the excitement and the attention
that the Altair did.

Likewise, Scelbi had an 8008-based computer before the Altair, I can't
remember exactly when, but at least for me, and likely others, it
wasn't noticed till after the Altair hit. I know the Scelbi was advertised
in the back of QST, but I only saw the ad when I looked for it after
the Altair hit the market and the ad was mentioned.

The SWTP 6800 came a bit later, I can't remember exactly when, but
of course it had the advantage that it was terminal based. No fiddling
with switches and strings of LEDs on the front panel, and surely their
absence made it simpler to build.

Michael

 

[Jonathan Kirwan]

On Sat, 3 Sep 2005 21:22:51 -0400, "jm" <nospam@garbagecan.com> wrote:

Not "really" being wrapped up in computers back when the Z80, the Altair and
so on came out, I had forgotten about the KIM and so on. My question is -
trying to sort out my memory here - was the Altair 8800 sold be SWTP? OR a
different monster altogether? I DO recall the Altair now that it has been
mentioned - but may be getting it confused with South West Technical
Products - products.

The Altair 8800 was 'advertised' on two issues of Popular Electronics
circa the beginning of 1975. You can see it here:

http://www.computermuseum.20m.com/popelectronics.htm

I bought mine in January 1975 and assembled it over the next month or
so. It was sold my MITS, which was a company that used to make
calculator kits, back in the days when calculators were expensive and
selling kits actually made some money. They also had contracts with
NASA, I think. But after the huge budget cuts of 1970, after we got
to the moon, and the gasoline crisis, all hell broke loose and
companies like MITS went into red ink and started looking for
something else to do. Luckily, Intel had just had Intersil drop a
contract (but largely paid for, already) for a cpu for a terminal, for
which they were making the 8008, if I recall. Intel was rolling that
into the 8080 to sell as a micro just about the time MITS was starving
and looking for work. The Altair 8800 was the result.

But I'm open to corrections on the above. That's just what my poor
memory reminds me of.

SWTP was, at least from my point of view, a later-on company. I
hadn't heard of them until well after the Altair 8800 assembly I did.

Jon

 

[Jonathan Kirwan]

On Sat, 3 Sep 2005 22:07:29 -0400, "Art" <arthurgernberg@comcast.net>
wrote:

Altair 8080

8800.

Jon

 

[Michael Black]

Jonathan Kirwan (jkirwan@easystreet.com) writes:

On Sat, 3 Sep 2005 21:22:51 -0400, "jm" <nospam@garbagecan.com> wrote:

Not "really" being wrapped up in computers back when the Z80, the Altair and
so on came out, I had forgotten about the KIM and so on. My question is -
trying to sort out my memory here - was the Altair 8800 sold be SWTP? OR a
different monster altogether? I DO recall the Altair now that it has been
mentioned - but may be getting it confused with South West Technical
Products - products.

The Altair 8800 was 'advertised' on two issues of Popular Electronics
circa the beginning of 1975. You can see it here:

http://www.computermuseum.20m.com/popelectronics.htm

I bought mine in January 1975 and assembled it over the next month or
so. It was sold my MITS, which was a company that used to make
calculator kits, back in the days when calculators were expensive and
selling kits actually made some money. They also had contracts with
NASA, I think. But after the huge budget cuts of 1970, after we got
to the moon, and the gasoline crisis, all hell broke loose and
companies like MITS went into red ink and started looking for
something else to do.

No, MITS had nothing to do with NASA.

They were a small company that started by selling some rocketry related
electronic kits, and used "MITS" to suggest MIT/Massachusets Institute
of Technology.

They went the usual route, selling kits and counting on articles in
the hobby electronic magazines to run articles (which they wrote)
as promotion.

When calculators were feasible, they started making them as kits.
The November 1971 issue of Popular Electronics has their calculator,
I think it was their first, on the cover. They were a new thing
at the time, and even though expensive they were still a good price
if one needed such a thing, compared to the cost of what came before.

But as things evolved, the big companies came into the market, just
as with digital watches (I can't recall if MITS made those) where
small companies were in early and then lost to big companies. MITS
couldn't compete with TI and the other big companies in the calculator
business after they came into the field, and then nearly went bankrupt
as a result. Legend says the Altair was a last minute attempt to
save the company.

Luckily, Intel had just had Intersil drop a
contract (but largely paid for, already) for a cpu for a terminal, for
which they were making the 8008, if I recall. Intel was rolling that
into the 8080 to sell as a micro just about the time MITS was starving
and looking for work. The Altair 8800 was the result.

It wasn't Intersil, it was Busicom that wanted a calculator IC. Intel

convinced them a general purpose CPU would be the best solution, and
the result was the 4004. The 8008 was developed for a terminal
manufacturer, but not Intersil, who of course manufactured
seminconductors, mostly analog. By the time they came out with the 8080,
they weren't designing it for anyone.

And as I've pointed out, others had already come out with "home computers"
before the Altair, and while we hobbyists likely hadn't hard of
the 8080 before the Altair hit the cover of Popular Electronics,
I think they already had a level of familiarity and usage in professional
circles.

Michael

 

[Michael Black]

"Art" (arthurgernberg@comcast.net) writes:

May even run across some links to the Altair 8080 systems that preceeded
many "user Friendly" devices. These were once offeres in a kit of parts and
fair instruction manual. Basic, if my memory serves me, was the op-sys du
jour. Others may corect me if in error?? Item I had actually used Octal
Nixie Tubes for Hex Dec output which we manually decoded.

But one thing about the Altair is that it needed so much to get going.
The front panel (which wasn't just the switches and the LEDs, but I
gather rather extensive TTL), and the CPU board had no memory so
you needed an extra board for that, and of course then you needed
the motherboard so you could connect the boards.

That bootstrapping project leaves it relatively simple. Even something
like the SWTP 6800 CPU board could be standalone I think,
because it had memory however tiny and the monitor in ROM and a software
UART.

One reason the Cosmac Elf was so popular, relative speaking, was that it
didn't take many parts to wire up, and you could have it running as soon
as it was wired. It was made for bootstrapping without ROM. The problem
there is that 1802's were never that common back then, and scrounging one
up will likely require much effort at this point.

Michael

 

[Michael A. Terrell]

Jonathan Kirwan wrote:

SWTP was, at least from my point of view, a later-on company. I
hadn't heard of them until well after the Altair 8800 assembly I did.

Jon

SWTP was already in the kit business before kit computers hit the
market. They sold kits of parts for a lot of Popular Electronics
articles from the late '60s, on.

--
Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Michael Black wrote:

No, MITS had nothing to do with NASA.

They were a small company that started by selling some rocketry related
electronic kits, and used "MITS" to suggest MIT/Massachusets Institute
of Technology.

MITS was "Micro Instrumentation Telemetry Systems".

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida

 

[Jonathan Kirwan]

On Sun, 04 Sep 2005 05:26:49 GMT, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

Jonathan Kirwan wrote:

SWTP was, at least from my point of view, a later-on company. I
hadn't heard of them until well after the Altair 8800 assembly I did.

Jon


SWTP was already in the kit business before kit computers hit the
market. They sold kits of parts for a lot of Popular Electronics
articles from the late '60s, on.

Okay. Then it was only the ordering of my own experience here and not
fact. Thanks!

Jon

 

[Jonathan Kirwan]

On 4 Sep 2005 03:59:50 GMT, et472@FreeNet.Carleton.CA (Michael Black)
wrote:

Jonathan Kirwan (jkirwan@easystreet.com) writes:
On Sat, 3 Sep 2005 21:22:51 -0400, "jm" <nospam@garbagecan.com> wrote:

Not "really" being wrapped up in computers back when the Z80, the Altair and
so on came out, I had forgotten about the KIM and so on. My question is -
trying to sort out my memory here - was the Altair 8800 sold be SWTP? OR a
different monster altogether? I DO recall the Altair now that it has been
mentioned - but may be getting it confused with South West Technical
Products - products.

The Altair 8800 was 'advertised' on two issues of Popular Electronics
circa the beginning of 1975. You can see it here:

http://www.computermuseum.20m.com/popelectronics.htm

I bought mine in January 1975 and assembled it over the next month or
so. It was sold my MITS, which was a company that used to make
calculator kits, back in the days when calculators were expensive and
selling kits actually made some money. They also had contracts with
NASA, I think. But after the huge budget cuts of 1970, after we got
to the moon, and the gasoline crisis, all hell broke loose and
companies like MITS went into red ink and started looking for
something else to do.

No, MITS had nothing to do with NASA.

My memory is definitely fading! Thanks! I seem to recall reading
some 'history' on MITS circa the late 1970's that included some
comment along those lines. But I appreciate the correction and I'll
try and kill that 'recollection' of mine!

They were a small company that started by selling some rocketry related
electronic kits, and used "MITS" to suggest MIT/Massachusets Institute
of Technology.

Ah! Perhaps that was what my memory distorted over the years...

They went the usual route, selling kits and counting on articles in
the hobby electronic magazines to run articles (which they wrote)
as promotion.

When calculators were feasible, they started making them as kits.
The November 1971 issue of Popular Electronics has their calculator,

I remember seeing some tiny partial-column ads from them and thinking
about buying one. But it was too much for me at the time. I just
kept using a slide rule.

I think it was their first, on the cover. They were a new thing
at the time, and even though expensive they were still a good price
if one needed such a thing, compared to the cost of what came before.

But as things evolved, the big companies came into the market, just
as with digital watches (I can't recall if MITS made those) where
small companies were in early and then lost to big companies. MITS
couldn't compete with TI and the other big companies in the calculator
business after they came into the field, and then nearly went bankrupt
as a result. Legend says the Altair was a last minute attempt to
save the company.

I've heard that, too.

Luckily, Intel had just had Intersil drop a
contract (but largely paid for, already) for a cpu for a terminal, for
which they were making the 8008, if I recall. Intel was rolling that
into the 8080 to sell as a micro just about the time MITS was starving
and looking for work. The Altair 8800 was the result.

It wasn't Intersil, it was Busicom that wanted a calculator IC.

No, I think you are thinking earlier than I was thinking. Isn't
Busicom a Japanese company that started the whole ball rolling with
Intel?

Anyway, I was thinking actually later than the late 1960's. And it
was definitely something to replace a lot of discrete logic in the
body of a glass terminal. Not a calculator.

Intel
convinced them a general purpose CPU would be the best solution, and
the result was the 4004.

Fully agreed, here.

The 8008 was developed for a terminal
manufacturer, but not Intersil, who of course manufactured
seminconductors, mostly analog.

Who was it, then? Do you know?

By the time they came out with the 8080,
they weren't designing it for anyone.

Yes, that's what I have heard as well. Something along the lines of
'productizing' what they had left off with on the terminal project.

And as I've pointed out, others had already come out with "home computers"
before the Altair, and while we hobbyists likely hadn't hard of
the 8080 before the Altair hit the cover of Popular Electronics,
I think they already had a level of familiarity and usage in professional
circles.

Since I was just 19 at the time, I wasn't in those circles.

Thanks!

Jon