z80 Processor

z80 » Beginner

The TI86 runs on a z80 microprocessor put out by ZiLOG around 1974. The z80 is like a dinosaur to the computer business having been built about 25 years ago and so you can buy a handful of z80 chips for under a dollar!

The reason why TI picked it is because the z80 is relatively small, uses little battery power, and doesn't put off much heat at all. If you were to crack open your computer and feel the inside of it when it's running, you'd realize that it's hot. That's because the processor is using tons of little electrical charges to run itself and those electrical charges mean heat. That heat is why you have a fan on the back of the computer to cool it down. The TI86 doesn't have enough space to put a fan on the back of it.

The z80 was originally only designed to run at 2 MHz but TI bumped it up to between 4 to 4.8 MHz by adding peripherals, making it plenty fast for what we have in mind: games.

The z80 was a hack of Intel's 8080.

The chips have 5-V-only operation, no glue chips, and easy asm language when compared to other processors of its time. It uses an external 8-bit data bus while it can only access 64k of memory at a time, 2 linear number register sets with one register plane, and a CPU speed of 10. The z80 carries a four clocks per instructions a minute speed.

When the z80 was originally put out, it was the best out there; you can compare it to the Pentium III 700 mhz or more, which by the time you read this will probably be nothing.

Read more: "How z80's registers are implemented"