Hi all,

Therefore, I decided to design and build a complete computer with vacuum-tube technology from scratch. A short description of the project is enclosed,

Program code is 24 bit wide, i.e. each operation occupies two 12 bit words. The first word is the opcode, the second word is a. the address or b. an immediate value Three 19" racks are used. The bottom of each rack holds the power supplies (good old Seymour style), the upper parts a total of about 30 card cages for standard Euro cards 100 mm x 160 mm. Each cage can hold up to 14 cards. Standard 19" mechanical components are used for cost and availablity reason. Ventilation is by off-the-shelf 19" ventilator assemblies. There are four types of cards: a. logic and registers (approx. 200 used) b. clock drivers (approx. 25 used) c. core sense amplifiers (12 used) d. core drivers (19 used) Types a,b use the same printed circuit board, differing parts mounting. Types c, d are different. The tubes used have been selected according to availability of surplus stocks. Starting from surplus stock lists, the most suitable tube for each purpose has been selected, resulting in average cost of less than 1 US$ per tube. Types a and c use 6BQ7A miniature dual triodes, two per card, approx. 400 tubes total. Type b uses 6CW5 miniature power pentodes, two per card, approx. 50 tubes total. Type d uses 40KG6 beam power pentodes, four per card, 76 tubes total.