Day: November 7, 2023

NEC V20 - Konstantin Lanzet, CC BY-SA 3.0 via Wikimedia Commons

Intel V. NEC : The Case Of The V20’s Microcode

November 7, 2023 by 18 Comments

Back in the last century, Intel saw itself faced with a need to have ‘second source’ suppliers of its 8088 and 8086 processors, which saw NEC being roped in to be one of those alternative suppliers to keep Intel’s customers happy with the μPD 8086 and μPD 8088 offerings. Yet rather than using the Intel provided design files, NEC reverse-engineered the Intel CPUs, which led to Intel suing NEC over copying the microcode that forms an integral part of the x86 architecture. In a recent The Chip Letter entry by [Babbage] this case is covered in detail.

Although this lawsuit was cleared up, and NEC licensed the microcode from Intel, this didn’t stop NEC from creating their 8086 and 8088 compatible CPUs in the form of the V30 and V20 respectively. Although these were pin- and ISA-compatible, the internal microcode was distinct from the Intel microcode due to the different internal microarchitecture. In addition the V20 and V30 also had a special 8080 mode, that provided partial compatibility with Z80 software.

Long story short, Intel sued NEC with accusations of copyright infringement of the microcode, which led to years of legal battle, which both set many precedents about what is copyrightable about microcode, and ultimately cleared NEC to keep selling the V20 and V30. Unfortunately by then the 1990s had already arrived, and sales of the NEC chips had not been brisk due to the legal issues while Intel’s new 80386 CPU had taken the market by storm. This left NEC’s x86-compatible CPUs legacy mostly in the form of legal precedents, instead of the technological achievements it had hoped for, and set the tone for the computer market of the 1990s.

Thanks to [Stephen Walters] for the tip.

Nixie Tube RPN Calculator Project

November 7, 2023 by 12 Comments

If you like Nixie tubes and/or DIY calculators, checkout this interesting talk from the HP Handheld Conference in Orlando last month by [Eric Smith] from Brouhaha and [John Doran] from Time Fracture. For 20-some years, [Eric] and the late [Richard Ottosen] have been incrementally developing various DIY calculators — this paper from the 2005 HHC conference is an excellent overview of the early project. [John] got one of those early DIY calculators and set about modifying it to use Nixie tubes. However, he got distracted by other things and set it aside — until reviving it earlier this year and enlisting [Eric]’s aid.

This presentation goes over the hardware aspects of the design. Unlike the earlier PIC-based DIY calculators, they decided to use a WCH RISC-V processor this time around. The calculator’s architecture is intentionally modular, with the display and keyboard housed in completely separate enclosures communicating by a serial interface. If the bulkiness alone doesn’t exclude it from being pocket-sized, the 170 VDC power supply and 1/2 W per digit power consumption certainly does. This modularity does lend itself to DIYers replacing the display, or the keyboard, with something different. [Eric] wants to build a mechanical flip-digit display for his unit. As for the software, [Eric] reviews the firmware approach and some future upgrades, such as making it programmable and emulating other flavors of HP calculators.

If you’re embarking on a similar project yourself, check out this talk and take notes — there are a lot of interesting tidbits on using Nixie tubes in the 21st century. If [Eric]’s name sounds familiar, you may know him from the Nonpareil calculator software used on many emulators and DIY calculator projects, one of which we covered some years ago. [John] is also a long-time tinkerer, and we wrote about his gorgeous D16/M HCMOS computer system back in 2012. Thanks to [Stephen Walters] for sending in the tip.

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