Content deleted Content added
→History: mention why it's a good match for calculators, with reference, etc. |
|||
Line 14:
[[File:Olympia CD700 Desktop Calculator. 1971.Microprogrammable Arithmetic Processor System Devices (MAPS).jpg|thumb|Olympia CD700 Desktop Calculator using the National Semiconductor MAPS MM570X [[bit-serial]] 4-bit microcontroller]]
[[File:Alps remote control BHR970001B-7517.jpg|thumb|left|Infrared remote control PCB - an [[infrared remote control]] transmitter controlled by a NEC D63GS 4-bit microcontroller]]
A 4-bit processor may seem limited, but it is a good match for calculators, where each decimal digit fits into four bits.<ref name="Shirriff_TMS1000" />
Some of the first [[microprocessor]]s had a 4-bit word length and were developed around 1970. The first commercial microprocessor was the [[binary-coded decimal]] (BCD-based) [[Intel 4004]],<ref name="Mack_2005" /><ref name="Hofstra_History" /> developed for calculator applications in 1971; it had a 4-bit word length, but had 8-bit instructions and 12-bit addresses. It was succeeded by the [[Intel 4040]].
The first commercial single-chip computer was the 4-bit TMS1000 (1974).<ref name="Shirriff_TMS1000">
Ken Shirriff.
[https://www.righto.com/2020/11/reverse-engineering-ram-storage-in.html "Reverse engineering RAM storage in early Texas Instruments calculator chips"].
</ref>
The [[Texas Instruments]] [[TMS 1000]] (1974) was a 4-bit [[central processing unit|CPU]]; it had a [[Harvard architecture]], with an on-chip instruction ROM, 8-bit-wide instructions and an on-chip data RAM with 4-bit words.<ref name="TI_1976_TMS1000" />
| |||