NEC X86 Microprocessors - NEC V20, NEC V25, NEC V30 (Paperback)

Chapters: Nec V20, Nec V25, Nec V30. Source: Wikipedia. Pages: 17. Not illustrated. Free updates online. Purchase includes a free trial membership in the publisher's book club where you can select from more than a million books without charge. Excerpt: The NEC V20 (PD70108) was a processor made by NEC that was a reverse-engineered, pin-compatible version of the Intel 8088 with an instruction set compatible with the Intel 80186. The chip featured approximately 29,000 transistors, ran at 8 to 16 MHz and was around 30% faster (application dependent) than the 8088 at the same clock speed, primarily due to a hardware multiplier (whereas the 8088 had to perform multiplication using a microcode program). NEC V20 was used in "turbo" versions of some PC clones such as Commodore PC compatible systems, Copam, and Tandy 1110 laptop series. Also used in the Casio PV-S450 PDA. Sony also produced this microprocessor under license from NEC as the V20H (Sony CXQ70108). An unusual feature of the NEC V20 was that it added an Intel 8080 emulation mode, in which it could execute programs written for the Intel 8080 processors. The instructions BRKEM executed in 8086 mode (NEC used a different notation for the instructions than Intel and BRK in NEC notation = INT in Intel notation) and RETEM and CALLN executed in 8080 mode was used to switch/return to/from the emulation mode. There was a V2080 CPeMulator program which allowed to run 8080-based CP/M-80 programs on a MS-DOS machine. NEC V30, 10MHz.The NEC V30 (PD70116) was a version of the NEC V20 that was pin compatible with the 16-bit data bus Intel 8086 processor. It was used in the GTD-5 EAX Class 5 central office as a drop-in performance upgrade for the processor complex in the late 1980s. It was also used in the Psion Series 3, in the NEC PC-9801, the Applied Engineering "PC Transporter" emulator for the Apple II series of computers, and in various arcade machines (particularly ones made by Ir...More: http: //booksllc.net/?id=55354