【USAC Electronic Industrial Co.,Uchida Yoko】 USAC 720 Series

This was a series of ultra-small computers developed by USAC Electronic Industrial Co., (currently PFU), and marketed by Uchida Yoko. It was the first series in its class in Japan to feature uniform architecture and software throughout the series. The USAC 720 Series was comprised of 5 models and the first model (the USAC 720/10) was completed in September 1971. This series had the following features.
(1) It employed the byte system.
(2) It achieved simultaneous input/output operation and input/output unit standardization by using a true channel mechanism.
(3) An automatic inserter mechanism was standard equipment (font type serial printer).
(4) A macro assembler was provided.
(5) It achieved the functionality of a multi-billing system, which was the forerunner of multi-task systems.

USAC 720 Series Main Specifications
Model name USAC
Application Direct Data Processing (DDPS*) Primarily used for general ledger processing Multi-billing processing (simultaneously issuing different types of bills) Primarily online processing for aggregation and distribution of data Batch processing of high-volume data
Completion date September 1971 1972 January 1973
Main mem-
ory unit
Memory element Magnetic core
Capacity Max. 8KB Max. 16KB
External memory Externally mounted drum 131KB Disk cartridge 278KB
Printer Font type serial printer
15.5char/s (88 fonts), 130digit/line
Automatic inserter (standard)
Same as at left + Line printer (240line/min)
Other Bottom-end machine
Model completed first
Established DDPS
Employed magnetic general ledger (single-side 256B) Connection of a maximum of 3 workstations Dedicated line connection (1,200bps) Top-end machine
First use of a CRT display

*: "DDPS (Direct Data Processing System" is a system where the generated data is processed by directly inputting it to the system, on the spot, via a keyboard.

USAC720/10USAC 720/90