cCalc

cCalc is a feather-light and portable Windows utility that permits you to apply x86 CPU instructions to the system, in order to find out how they affect the registers and flags. It can also be used for calculating boolean algebra and creating bit masks.

Since there is no installation involved, you can drop the .exe file anywhere on the disk and simply click it to launch cCalc. Alternatively, you can move it to a USB flash drive to be able to directly run it on any computer with minimum effort. Moreover, it doesn't change the Windows registry configuration.

The GUI is user-friendly, made from a single window that shows all options available. The x86 instructions are SHL (Shift Left), SHR (Shift Right), SAR (Shift Arithmetically right), XCHG (Exchange Data), ROL (Rotate Left), ROR (Rotate Right), NEG (Two's complement negation) and NOT (Negate the operand).

You can specify the input in decimal or hexadecimal and view the signed value, as well as copy data to the Original 8086/8088 instruction set, where you can compare operands (CMP), perform additions, subtractions, unsigned multiplications and unsigned divisions (ADD, SUB, MUL and DIV).

You can compare operands logically (TEST), make additions with carry flags and subtractions with borrow (ADC and SBB), perform signed multiplications and signed divisions (IMUL and IDIV), as well as use the XOR, OR and AND operators.

Although cCalc doesn't implement buttons for copying data to the Clipboard, printing it or exporting it to file, the signed and operation values can be copied by making a text selection and opening the right-click menu or triggering the global Copy hotkey.

No error dialogs popped up in our tests, and the program didn't hang or crash. It had low impact on computer performance. CCalc offers a simple solution for executing various x86 CPU instructions to figure out how they affect registers and flags.