[rbanffy]

There is some controversy - you could actually use a TRS-80, an Apple II or a PET right after taking it out of the box.

I think that, if we define a personal computer as a machine that is designed for a single interactive user, the LGP-30 would be a good candidate. It was not, however, a home computer.

For me, a personal computer needs more than switches and LEDs as its UI. With a serial port, a terminal, and a monitor program in ROM, the Altair would qualify.

[anthk]

TRS-80, AII and the PET came later. You were right on the peripherals. Instead of a serial port, I'd set a TV output with a keyboard as an input, and the Altair would get far more sales.

[fortran77]

The people I know who put together Altairs in 1975 used ASR-33 teletypes as terminals to run BASIC.

[TheOtherHobbes]

Teletype and all, the Altair looked and worked like an cut-down entry-level version of the minis that were popular in engineering and science.

Not as powerful as a PDP-8, but less than a tenth of the price.

It was the perfect aspirational project for the electronics hobbyist community of the time.

The fact that you could barely do anything with it wasn't the point. It was a real computer you could set up at home and use without time restrictions or hourly billing.

The S-100 bus market turned into a preview of the PC market. S-100 systems soon sprouted real terminals, floppy drives, and workable memory, and began to appear in the offices of accountants and other non-tech professionals.

The IBM PC probably wouldn't have happened without it. It normalised relatively affordable computing, and the idea of a third party market of expansion cards on a standard bus.

[SoftTalker]

A TV output means you need to create (and have memory dedicated to) the video. A serial port is much simpler.

[rbanffy]

A 16x64 character screen like the TRS-80 needed 1k of RAM. IIRC, the Altair didn’t have that much memory out of the box.

The video memory would either be in the computer or the terminal. At least if it were in the computer, you could use it for other stuff.

[SoftTalker]

Did it not have a serial port? Would have assumed that connecting it to a terminal or teletype was the standard thing.

[maj0rhn]

We had an Altair at home, that my father assembled from a kit. That version did not have a serial port. It had only the switches on the front panel. I did succeed in inputting some programs and in having them run. But of course it was appallingly limited.

The serial port was its own separate board. https://www.youtube.com/watch?v=RaYTd3dbXeM

There were two very clever I/O ideas that emerged for the Altair: (1) A radio on top of the housing would pick up a signal, allowing audio output! (2) A cassette tape recorder could be used as an external storage device, though I forget how it interfaced... the serial board, I think.

[whartung]

My first computing experience was with an IMSAI 8080 that class assembled the year before.

It had a keyboard and video board, rather than a terminal. The monitor was open chassis to boot (ah the old days when we didn’t protect children from lethal electricity).

It had a ROM monitor and cassette tape. You had to type in (in hex) a short machine language program into the monitor to load BASIC from a cassette. We simply never turned it off.

I tried ti enter the bootstrap through the front panel once, but I made some mistake, and it didn’t work. It was an awful enough experience I never tried again.

[jmount]

Ah man- the power supply in the IMSAI 8080 was scary enough, plus you had the monitor power supply open. Fun times- the "book" sequence on ours was "fat finger in the paper tape reading software, read the cassette IO software from paper tape, load BASIC from cassette, and good to go."

[ebruchez]

One of the interesting aspects of the Altair was that it was based on a bus called the S-100 bus. You would have a CPU card and a memory card at least, but everything else was optional. The serial board was separate, and strictly not absolutely necessary to play with the computer, since you could enter simple programs directly from the front panel.

[SoftTalker]

I remember S-100 from when I was a kid. Never was hands-on with that hardware but there were all kinds of ads for cards in Byte magazine and others. Seemed like you could get a card for almost anything in S-100 protocol.

[ebruchez]

That's right. There are still S-100 enthusiasts who are maintaining and developing S-100 cards, see http://www.s100computers.com/ (does not seem to respond correctly to HTTPS right now).

[dowager_dan99]

keep the historical context in mind. There were people who wanted a computer at home and people who wanted to bring home the experience they got with access to powerful mainframe & minicomputers at work or school, so there was both a push to build your own computer and a desire to build IO devices like teletypes. The combo, all-in-one is the real revolution (IMO) that you got with the Apple II or the Sol. The TRS-80s and PETs feel a lot more like early commercialization in comparison. Woz was motivated by showing off what he could create, because that's how he communicated. It makes sense that a keyboard and TV - with graphics - shows off way better, same with being able to program in basic "... for $300 you can build a computer that's so good you can type programs on it and run them..."