Mark-8

"Build your own Mark-8". This title appeared on the front cover of the July issue 1974 of an electronic hobbyist magazine called Radio-Electronics.

The Mark-8 was an Intel 8008 / 256 bytes RAM memory based system without neither ROM monitor, power supply, case, video, keyboard, nor backup interface. Consequently, the user had to enter program instructions each time he turned the system on.

To build it, the home computing fanatic had first to buy the $5.50 48-page instruction manual written by Jon Titus, the creator of the system. Then order the circuit board from an Englewood, New Jersey based company for $47.50, and finally purchase various components, including the Intel 8008 processor for a total of $250. About 7500 home computing fans ordered the instruction manual and 400 of them the main board. Very few of them succeeded in running the final assembled system, as it was a very long and full of traps job.

The LED display featured 4 rows of 8 LEDs. The two upper rows displayed the address bus (14 LEDs) and processor cycle state (2 LEDs). The third row displays an 8-bit memory data, and the fourth, the 8-bit value available from the output port 0.

Most of the enthusiasts who tried to bring the Mark-8 to a running state gave up and bought a few months later the first versions of the Altair 8800 - the first real personal home computer. About 15 original Mark-8 computers are known to exist today.