GIM SBA
Developer	General Instrument
Manufacturer	General Instrument
Type	microcontrollers
Production	November, 1977
Architecture	1-bit
ISA	SBA
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.

Members

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?

Architecture

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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ISA

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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