As of June 2024, the venerable Z80 microprocessor, launched by Zilog in 1976, will now not be out there as a standalone half.
Zilog Z80 die, date code 1990. Picture used courtesy of ZeptoBars (CC BY 3.0 Unported)
Regardless of the numerous evolutions and revolutions within the engineering business, some silicon goes again many years. You’ll be able to nonetheless jump over to DigiKey or Mouser and place an order for an NE555 timer, first produced in 1971, or an LM741 op amp from 1968. These chips are icons of the start of integrated-circuit electronics. The lifecycle of the Z80, equally salient to that period, has now come to an finish.
The Intel 8080 and the Beginning of the Zilog Z80
Zilog, now owned by Littlefuse, was born from the race to the single-chip microprocessor. Zilog’s principal founder, Federico Faggin, developed the 4-bit Intel 4004, usually considered the primary industrial single-chip microprocessor, and the 8-bit Intel 8008.
He was additionally instrumental in enhancing the follow-on processors, the 4040 and 8080. The 8080, launched in 1974, was the primary high-performance 8-bit microprocessor. It was extra highly effective, and it may instantly deal with 64 Ok of RAM. It was additionally simpler to interface than Intel’s prior microprocessor chips.
Faggin, nevertheless, wished extra for the microprocessor than Intel did on the time. Because the story goes, Intel was extra centered on promoting static RAM and ROM and largely noticed the microprocessor as a approach to promote extra reminiscence chips slightly than as a invaluable product by itself. He left Intel in late 1974 together with Ralph Ungermann to discovered Zilog. The 2 initially set their sights on designing a low-cost, single-chip microcontroller. Nevertheless, with out their very own fab functionality, the product wouldn’t be economically viable as a consequence of robust competitors and low margins. With that concept put aside, they determined to develop an improved microprocessor chip that was suitable with the favored 8080.
Z80 CPU in a 40-pin DIP bundle, date code 1983. Picture by Duane Benson
The brand new chip could be 8080 code suitable however with 120 extra opcodes, extra registers, and separate I/O and reminiscence area. The Z80 makes use of a single + 5-volt energy provide as a substitute of the +5/-5/+12-volt break up provide required by the 8080. It didn’t require an exterior clock chip and will single-step for debugging. Zilog initially contracted with Mostek, developer of the competing 6502 microprocessor, to fab the Z80.
Into the Private Laptop
By the point the Z80 was launched, the 8080-based Altair 8800 and IMSAI 8080 desktop computer systems, with their S100 bus, had already turn out to be a normal platform for package and semi-kit computer systems. Gary Kildall of Digital Analysis had additionally focused the 8080 at CP/M working methods. In different phrases, the platform and working system have been prepared and ready for the Z80 to reach.
The Z80, with its 8080 binary compatibility, single provide voltage, and decreased help chip necessities, simply suits on a single card in a desktop S100 “mainframe” field. The Z80 powered the Nineteen Seventies’ three hottest S100 bus small enterprise laptop strains from Cromemco, Vector Graphic, and North Star. For the primary time, workplace customers may run phrase processing software program like WordStar or database administration like dBase II with out resorting to large system timeshare or costly minicomputers.
Cromemco S100 bus single board Z80 laptop as pictured in Byte Journal, September 1979. Picture used courtesy of Web Archive
The Z80 prevailed as probably the most extensively used 8-bit CPU by the mid-Nineteen Seventies till being supplanted by the Intel 8088-based IBM PC within the early Nineteen Eighties. Customers noticed the primary appliance-like residence laptop with the introduction of the Z80-powered Radio Shack TRS-80 in 1977. The TRS-80 put the Z80 up in opposition to the Mostek 6502, which drove the Apple II and the Commodore PET as contenders for the dominant private laptop CPU.
The primary “moveable” computer systems have been Z80-powered. The Kaypro II and Osborn I—with their twin floppy disks, cathode ray tube (CRT) shows, and keyboards in a self-contained, luggable 25+ pound field—have been powered by the Z80 and ran the CP/M working system.
Z80 as an Embedded Gadget
By the mid-Nineteen Eighties, 8-bit CPUs have been deemed insufficient within the enterprise private laptop world in opposition to the likes of the IBM PC and Motorola 68000-based Apple Macintosh. Zilog’s makes an attempt at 16- and 32-bit follow-on PC microprocessors within the Nineteen Eighties—the Z800, Z8000, and Z80000—did not succeed due to the entrenchment of Intel’s x86 structure.
Nonetheless, the Z80 soldiered on. The chip had a big following of many succesful programmers. It was cheap and straightforward to implement, and the embedded world benefitted from these benefits. The Z80 discovered houses in printers, photocopiers, fax machines, modems, and a bunch of commercial, industrial, and scientific tools. One of many largest put in bases of Z80 microprocessors comes with the Texas Devices Ti-8X sequence of graphing calculators. Most are powered by the Z80, placing the processor within the arms of thousands and thousands of scholars worldwide.
Goodbye, Z80, My Previous Good friend
As a result of the growing old Z80 structure can’t compete with 8-bit RISC and low-cost 32-bit embedded processors, Zilog has determined to discontinue the road. The variations of the Z80 to be discontinued are available in NMOS with clock speeds starting from 4 MHz to eight MHz and CMOS operating from 8 MHz to twenty MHz. These embody:
- Z84C0006VEG
- Z84C0006PEG
- Z84C001PEG
- Z84C0008AEG
- Z84C0020VEG
- Z84C0008PEG
- Z84C0010AEG
- Z84C0010VEG00TR
- Z84C0020AEG
- Z84C0020PEG
- Z84C0006AEG
Zilog will settle for last-time purchase orders till June 14, 2024.
Traces of the Z80 will nonetheless dwell on. Z80 smooth cores can be found for implementation in FPGAs, and the eZ80 is an enhanced structure by-product embedded processor that’s Z80 code suitable however a lot sooner and extra trendy in reminiscence addressing and interfacing.
; Z80 Signing off ORG 0000H ; Set program origin to 0000 HALT ; So lengthy, and thanks for all of the opcodes END