"Practical Electronics" magazine article on building "Champ" 4040 microcomputer

Intel 4004 and 4040 4-bit processor development kit with Busicom 141-PF calculator emulation

Single Board Computer using Intel 4040

Decimal arithmetic subroutines for the Intel 4004 or 4040 CPU

A 16 bit random number generator for the Intel 4004 or 4040 CPU

Calculate register values for Intel 4004 and 4040 delay loops

A clock divider module that uses 4040 chip. It divides by 2; 4; 8; 16; 32; 64; 128; 226; 512; 1024; 2048; 4096.