Photo Credits

• abacus.gif from Michael R. Williams, A History of Computing, Prentice-Hall, 1985, p. 68.
• carry.gif from Williams, p. 128.
• pascaline.gif from Williams, p. 131.
• differnece.gif from Williams, p. 170.
• analytic-mill.gif from Williams, p. 191.
• jacquard.gif from G. Michael Schneider and Judith L. Gersting, An Invitation to Computer Science, PWS, 1999, p. 210.