at 2 MHz. Most higher-line calculators in the series, starting with the TI-82 and TI-85, clock their Z80 CPUs at 6 MHz or higher. (A few models with TI-8x names use other CPUs, such as the M68000, but the vast majority are Z80-based. On those, it is possible to run assembled or compiled user programs in the form of Z80 machine-language code.) The TI-84 Plus series, introduced in 2004, is still in production as of 2020. The TI-84 Plus CE series, introduced in 2015, uses the Z80-derived Zilog eZ80 processor and is also still in production as of 2020. In the late 1980s, a series of Soviet landline phones called "AON" featured the Z80; these phones expanded the feature set of the landline with caller ID, different ringtones based on the caller, speed dial and so forth. In the second half of nineties manufacturers of these phones switched to 8051 compatible MCUs to reduce power consumption and prevent compact wall warts from overheating. See also Zilog eZ80 S-100 bus SymbOS Z88DK Micro-Professor MPF-I, Z80 training system Footnotes References Sources Further reading Datasheets and manuals Z80 Datasheet (NMOS); Zilog; 10 pages; 1978. Z80 Data Book (NMOS); Zilog; 131 pages; 1978. Z80 Datasheet (NMOS and CMOS); Zilog; 36 pages; 2002. Errata Z80 User Manual (NMOS and CMOS); Zilog; 332 pages; 2016. Z80 Peripheral User Manual (NMOS and CMOS); Zilog; 330 pages; 2001. Hardware books Build Your Own Z80 Computer - Design Guidelines and Application Notes; 1st Ed; Steve Ciarcia; Byte Books; 332 pages; 1981; . (archive) Z80 Microprocessor - Architecture, Interfacing, Programming, and Design; 1st Ed; Ramesh Gaonkar; Macmillan; 674 pages; 1988; . (archive) Z80 Users Manual - Pin Definitions, Control Signals, Peripherals, and More; 1st Ed; Joseph Carr; Reston; 338 pages; 1980; . (archive) Microprocessor Interfacing Techniques; 3rd Ed; Rodnay Zaks and Austin Lesea; Sybex; 466 pages; 1979; . (archive) Software books Programming the Z80; 3rd Ed; Rodnay Zaks; Sybex; 630 pages; 1980; . (archive) Z80 Assembly Language Programming; 1st Ed; Lance Leventhal; Osborne/McGraw-Hill; 642 pages; 1979; . (archive) 8080/Z80 Assembly Language - Techniques for Improved Programming; 1st Ed; Alan Miller; John Wiley & Sons; 332 pages; 1981; . (archive) Z80 and 8080 Assembly Language Programming; 1st Ed; Kathe Spracklen; Hayden; 180 pages; 1979; . (archive) Practical Microcomputer Programming - The Z80 - including Source for Resident Assembler and Debug Monitor; 1st Ed; Walter Weller; Northern Technology; 501 pages; 1978; .