This is the User's Manual for the Heathkit ES-400 which was the first personal computer offered by Heath Company. The ES-400 was an analog computer that was offered in four different configurations: Small Computer ($520), Medium Computer ($760), Full Computer ($945) and Educational Computer ($1,550). In the 1957 catalog, the Small Computer was called the "Basic Computer Kit" and was only $495 and the Medium Computer was $775.
Several other rare documents accompanied this item. They included:

• an 8 x 10 inch b&w glossy photo of a completed ES-400. no marking anywhere on the photo
• two typewritten, stapled sheets of paper entitled, "Questions Most Asked About the Heathkit Analog Computer". There are 27 questions and answers.
• article by Chalmer E. Jones (Assistant to the President of Heath Company) entitled, "The Functional Considerations for a low cost electronic analog computer". It is marked in the upper right corner, "Paper No. 55-25-3".
• pamphlet entitled "Putting the Analog Computer to Work" by Carl Heald (Project Engineer for Heath Company. This is publication #20 in the part of the Engineers' Notebook series Number 20.
• Eight one page handouts giving specifications for the ES-400 cabinet along with various parts. Each page is dated and all are from between April and June of 1959.
• One four page color brochure describing the ES-400 and various parts. A price list is on the fourth page.
• a single page Heathkit news release from the office of C. M. Edwards, the Advertising Manager, announcing the EC-1 Analog computer.
• a stapled eight page handout describing the EC-1. The handout is dated November 18, 1959
• an 8 x 10 inch b&w photo of the EC-1. The front is marked "EC-1 (L)". The backed is stamped "Borkowski Advertising, 215 West Navarre, South Bend, Indiana".