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SBA - General Instrument
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Developer General Instrument
Manufacturer General Instrument
Type microcontrollers
Production November, 1977
Architecture 1-bit
Word size 1 bit
0.125 octets
0.25 nibbles
Technology nMOS
Clock 10 kHz-800 kHz
Package DIP40

The GI SBA (Sequential Boolean Analyzer) was a family of 1-bit microcontrollers developed by General Instrument's Microelectronics division. These microcontrollers served as cheap programmable logic controllers, replacing old relay system.


Part RAM ROM I/O Ports Notes
SBA 120x1 bits 1024x8 bits 31
SBA-1 120x1 bits 31 external storage
SBA-2 120x1 bits 2048x8 bits 31  ?ever released?


The SBA family had a large number (over 30) of I/O ports that could all be individually accessed programatically. Additionally, it had a relatively complex scheme of data storage. In total there were 120 words (1-bit each). This was broken down into 4 pages of 30 addresses each. The program had to choose which page it was working with currently and once that was done, any address selection was done on that page.

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Main article: SBA ISA

The SBA family had 8-bit instructions consisting of instructions with immediate and without immediate values. In total there were 24 instructions used for arithmetic, I/O, and page switching.

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designerGeneral Instrument +
full page namegeneral instrument/sba +
instance ofmicrocontroller family +
instruction set architectureSBA +
main designerGeneral Instrument +
manufacturerGeneral Instrument +
nameGIM SBA +
packageDIP40 +
technologynMOS +