Lawrence J. Krakauer's decimal computer
- This article is not detailed enough and needs to be expanded. Please help us by adding some more information.
Lawrence J. Krakauer's decimal computer was an educational language invented after 1965 for teaching programming to children in a camp. It was implemented as an emulator on a PDP-1 machine.
The computer has a memory of 1000 words, each a four-digit nonnegative number. Instructions are one word each, with a one digit opcode and a three-digit address or operand field. The computer can do simple arithmetic instructions on the one-word accumulator and a memory operand: add, subtract, multiply, divide. Oddly all four of these instructions are saturating, so subtraction results in 0 if the numerical result would be negative. It also has a jump and a conditional skip instruction, the latter skips if the comparison is equal. Indirect memory access is done using a code-modifying instruction that writes into the address field of an instruction. There are also custom IO devices defined.