CPMulator
| Company type | Private |
|---|---|
| Industry | Software development |
| Founded | 1984 |
| Founder | Jay Sprenkle |
| Products | CPMulator |
CPMulator is a software tool created in 1984 by Keystone Software Development, a company owned by Jay Sprenkle, designed to simulate the CP/M operating system on x86 DOS systems.
In the same year, the NEC V20 processor was launched, offering compatibility with the Intel 8088. This chip provided a slight enhancement in processing speed for IBM PC computers, especially benefiting applications that required intensive mathematical computations. Keystone Software took advantage of this development by advertising "PC Speedup Kits" in PCWeek magazine. The CPU’s socketed design made it simple to swap into IBM PCs, resulting in approximately a 5% increase in overall performance.
By utilizing the V20’s hardware feature to replicate the Intel 8080 instruction set, CPMulator allowed legacy CP/M programs to execute on IBM PC hardware. The software altered CP/M executable files to behave similarly to native 8088 DOS programs by adding initial code that switched the processor into emulation mode. It captured CP/M system requests, converted them into corresponding DOS commands, and smoothly transitioned back to emulation mode after execution.
The development of CPMulator ended as AT-class computers became prevalent and NEC did not manufacture a pin-compatible version of the 80286 processor suitable for this emulation technique.