Ishii Yoshiteru, Saito Masato, Yamada Akihiko, and others started developing the NEAC-2204 in 1960. The first unit was completed and shipped in September 1961.
The NEAC-2204 took the online, real-time processing and multi-program processing developed for the NEAC-2202 and added stored-program memory and file and I/O devices. The NEAC-2204 was able to execute seven separate programs simultaneously through CPU time-slicing with its stored-program memory. The developers used a magnetic drum for the main memory, since cost concerns outweighed performance, but they balanced this with the computation speed by using magnetic core buffer memory as cache memory. The NEAC-2204 could control up to seven I/O devices simultaneously thanks to a time-division methodology. Therefore, the computer supported many different I/O devices, including the NEAC-Writer, photoelectric tape readers, high-speed paper-tape punchers, card I/O devices, and high-speed teletypewriters.
The NEAC-2204 was designed to use inexpensive, high-capacity magnetic tape for data file maintenance. Part of the magnetic drum was used as a buffer to mitigate the speed differential between the computer and the tape.
The first unit was installed in the basement of Yamaichi Securities’ Fukuoka branch with the terminals located in the first floor office. During the day, the computer was used online to process securities transactions and afterhours it was left to batch process statistics and reports. In its own way, the NEAC-2402 was the harbinger of online banking.
| Completed | September 1961 | |||
|---|---|---|---|---|
| Computation method Control method | Fixed-point, serial, base10 Stored-program memory | |||
| Logic elements | transistors | 350 | ||
| diodes | 7,000 | |||
| magnetic cores | 360 | |||
| Word structure | Numeric words | 12 digits in base10 + sign (1 bit) | ||
| String words | One character (kana or symbols) represented with 2 digits | |||
| Instructions | 3 1/2 addressing system 14 index registers |
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| Computation speeds(using magnetic core memory) | Addition and subtraction | 1.5 ms | ||
| Multiplication | 33.5 ms | |||
| Division | 38.75 ms | |||
| Internal storage unit (core) | Magnetic drum | Main memory: | 3000 words | average call time: 13.7 ms |
| Loop memory: | 100 words | average call time: 3.7 ms | ||
| Magnetic core | Loop memory: | 100 words | average call time: 3.7 ms | |
| Magnetic tape unit | Magnetic tape units: | up to six | ||
| Read-write speed: | 120 words/second | |||
| One reel: | 380 meters long with a capacity of 100,000 words | |||
| I/O units | Photoelectric tape reader | 200 characters/second, up to four units | ||
| High-speed paper-tape punch | 50 characters/second, up to four units | |||
| High-speed teletypewriters | 200 characters/minute, 120 characters/line (with a 96-character set) 350 characters/minute, 120 characters/line (with a 48-character set) Up to three units of either type |
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| Card readers | 200 cards/minute, up to three units 100 cards/minute, up to three units |
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| NEAC-Writer | 100 cards/minute, up to seven units Print speed: 560 characters/minute Punch speed: 560 characters/minute Read speed: 560 characters/minute |
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