Hey guys,

I've stumbled upon this great video ( https://www.youtube.com/watch?v=cQIY3rl8ANU )in which a guy uses his altair 8800 to load a BASIC interpreter and run games. I recently just finished reading Charles Petzold's second edition of "Code" for the second time. In this book, he explains the intricacies of a processor and details how computer memory works, plus more.

Charles goes on to build a distilled version of the intel 8080 in the book. He briefly mentions that the altair 8800 used the intel 8080. In order to execute instructions with said altair 8800, one would need to enter the machine instructions via the data and memory switches on the front panel. What I don't understand is... Writing a BASIC interpreter in 8080 machine code would be a mammoth task. In this video how does his machine appear(or so it seems) to have the BASIC interpreter written into memory?

On a side note, I never knew the intel 8080 or altair 8800 could be hooked up to a monitor! How does the CPU work symbiotically with the monitor's graphics card to make characters appear on the screen?

Thanks!

He mentions it in the video. This particular machine has a ROM chip that automatically loads BASIC at startup. Even if that wasn't there, there are ways to avoid having to enter the same program over and over again by flipping physical switches. You'll notice there's a cassette deck on top of the Altair. That can be used to load data into memory. Back in the day there were also perforated tape readers that served the same purpose. That would have been the preferred method to program these machines back then.

I never knew the intel 8080 or altair 8800 could be hooked up to a monitor! How does the CPU work symbiotically with the monitor's graphics card to make characters appear on the screen?

It's not really a monitor, it's a terminal. The difference is that a monitor is directly controlled by the computer, while a terminal's screen is controlled by the terminal, and the terminal and computer exchange very simple commands to synchronize their states. "The user has pressed key X." "Output character Y." This is probably happening through some kind of serial interface.

There were optional serial interface and cassette interface boards that could be obtained and plugged in as the Altair used a s-100 bus system.

The 4K or 8K Basic ROM (depending upon how much memory was installed) was an optional extra!

The original Altair Basic was developed using a specially written 8080 simulator program for a DEC10 system. It was loaded into the Altair using paper-tape for the first demo of Basic.

Makes sense, thanks guys