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Holtek Semiconductor

Taiwan

Contents

Overview

Holtek Semiconductor Inc. is a Taiwanese semiconductor manufacturer. Their product range includes keyboard controllers.

Holtek’s website indicates that the company was established in 1998, yet their production selection guide notes that “After its establishment in 1983 and until the present day, Holtek Semiconductor has released an unceasing stream of competitive semiconductor devices onto the global market.” An HT6548 keyboard controller in a Delta AK-68 keyboard dated 9326 leaves the 1998 establishment date as somewhat suspicious. Holtek-branded microchips can be found as far back as 1992 (HT6030 with date code 9130, listed on eBay); HT-12E, a chip still manufactured into the 2010s, can be found (again on eBay) with no Holtek branding as far back as 1988 (date code 8846).

Products

Keyboard encoders

The following MCU-based keyboard encoders are known; this is not an exhaustive list and other models likely exist that have yet to be listed here. These chips are divided into two categories: dedicated keyboard encoders, and microcontrollers intended to be used as keyboard encoders. The latter type are documented as microcontrollers with the instruction set provided, with the customer presumably intended to supply their own keyboard encoder firmware. These specialist microcontrollers have found favour in a number of keyboard types including models from Costar and Cherry.

Model Type Protocols Form Found in Last order date
HT6547C Keyboard encoder AT, XT; Windows 95 ready DIP-40 ?
HT6547E Keyboard encoder PS/2 Japanese DOS/V; Windows 95 ready DIP-40 ?
HT6548 AT/XT switchable DIP-40 ?
HT82K28A Keyboard encoder PS/2; Windows 98 ready DIP-40, COB
HT82K68A One-time programmable MCU DIP-40, DIP-42, COB 2017-08-23
HT82K68E One-time programmable MCU DIP-40, DIP-42 2011-03-29
HT82K94A Mask programmable MCU USB 2.0 and PS/2 QFN-32, SSOP-48, LQFP-48, DIP-40 2015-06-22
HT82K94E One-time programmable MCU 2019-03-13
HT82K95A Mask programmable MCU USB 2.0 and PS/2 QFN-32, SOP-28, SSOP-48, LQFP-48 2020-03-31
HT82K95E One-time programmable MCU
HT82K96A Mask programmable MCU USB 2.0 and PS/2 SOP-28, SSOP-48 2014-12-26
HT82K96E One-time programmable MCU SOP-28, SSOP-48, COB
HT82K628A Keyboard encoder PS/2 DIP-40 2020-03-31
HT82K629 …, COB
  • Some Dell L100 keyboards (2006; COB); likely to be either A or B below
HT82K629A Keyboard encoder USB 1.1 and PS/2 auto-detect DIP-40 2020-03-31
HT82K629B Keyboard encoder USB 2.0/1.1 and PS/2 auto-detect QFN-46, LQFP-48

As of December 2021, HT82K95E/HT82K95A and HT82K629B are the only models listed on the Holtek website.

Keyboard controllers

Keyboard controllers are the motherboard-side chip that interacts with the keyboard and (with PS/2) mouse.

Model Type Protocols Form Found in Last order date
HT6542B Intel 8042-compatible PS/2 keyboard and mouse DIP-40, PLCC-44 ?

Regional

Holtek keyboard controllers were also produced under the “Regional” brand. Such chips have a river logo instead of the Holtek logo. There are two general forms of marking: the name “Regional” and the model number, or the model number and the production date. At present, the identity or meaning of “Regional” remains a mystery.

Regional keyboard controllers take the form of models HT6542 (with no suffix letter) and HT6542A. There is presently no evidence that Holtek branded chips with either part number; the lowest-known Holtek-branded equivalent is HT6542B. These chips are found not in keyboards but on motherboards, for example:

Documentation