The Texas Instruments SBP0400 (SBP = silicon bipolar), also known as SBC 0400 and X0400, is a microprogrammable

4-bit In computer architecture, 4-bit integers, or other data units are those that are 4 bits wide. Also, 4-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, or data buses of that si ...

slice processor that was introduced in 1976 (delivery began in December 1975). It was one of the first LSI processors and was the first device in the USA based on I²L technology (integrated injection logic). It was used for research and teaching purposes in the aerospace industry (

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

) and in the learning computer LCM-1001 (

Texas Instruments Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globall ...

, 1976). This microprocessor learning computer was probably the company's first.

Technical data

* technology: I²L (I/O pins are

TTL TTL may refer to: Photography * Through-the-lens metering, a camera feature * Zenit TTL, an SLR film camera named for its TTL metering capability Technology * Time to live, a computer data lifespan-limiting mechanism * Transistor–transistor lo ...

compatible) * number of gates: 1616 * gates per square millimeter: 81 * clock frequency: 1 MHz – max. 5 MHz *

arithmetic logic unit In computing, an arithmetic logic unit (ALU) is a Combinational logic, combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on ...

(ALU) with 16 operations, functionally similar to the

74181 The 74181 is a 4-bit slice arithmetic logic unit (ALU), implemented as a 7400 series TTL integrated circuit. The first complete ALU on a single chip, it was used as the arithmetic/logic core in the CPUs of many historically significant minicomp ...

* ten 4-bit registers: working register ( accumulator), extended working register, 8 general registers of which register 7 has a separate incrementer (intended as the

program counter The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), the instruction counter, or just part of the instruction sequencer, is ...

) * 9-bit microinstructions which are mapped through a

mask A mask is an object normally worn on the face, typically for protection, disguise, performance, or entertainment and often they have been employed for rituals and rights. Masks have been used since antiquity for both ceremonial and practic ...

-programmable

PLA PLA may refer to: Organizations Politics and military * People's Liberation Army, the armed forces of China and of the ruling Chinese Communist Party * People's Liberation Army (disambiguation) ** Irish National Liberation Army, formerly called ...

to a 20-bit internal control word which is stored in the 20-bit operations register in order to allow microinstruction pipelining * the default PLA implements 459 unique microinstructions (out of 512 microinstructions possible for 9 bit) * cascadable to form an 8/12/16 bit processor * parallel access to control functions, data-in, data-out, and address-out * 40-pin DIP (

dual in-line package In microelectronics, a dual in-line package (DIP or DIL), is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board (P ...

) * minimum supply voltage: 0,4 V

Teaching computer LCM-1001

In addition to the SBP0400, the learning computer contains a 74279 latch and a rechargeable battery. It is powered by a 7 V power supply unit. It is operated via a total of 20 toggle switches, which are divided into nine micro-operation switches, four data input switches, six control switches and the main switch. The switch position "down" or "left" corresponds to digital "0" or LOW; the position "up" or "right" corresponds to "1" or HIGH. The switch position at "1" is additionally indicated by a red LED lighting up. Nine further LEDs are used as output, four each for data and address, and one for ALUCOUT (ALU carry-out). The commands are entered bit by bit, whereby the 9-bit microinstruction word is divided into four ALU command bits, two target operand and three source operand bits. The least significant bit position (LSB) within each of the three groups is on the right. After each data input or expected output, the "CLOCK" push-button must be pressed to write the command to the command register and increase the command counter. Depending on the command used, the input is then made via the four data switches. The control switches are: ALUCIN (ripple-carry in), PCPRI (program counter priority, required to turn on the output LEDs on the address bus, PCCIN (program counter carry-in), ENCBY2 (enable program counter increment by a displacement of 1 or 2), POS1, POS0 (most significant, intermediate, or least significant position of the processor slice in a cascade). A DIL-40 socket serves as an optional extension by three further modules of the LCM-1000 series or own modules. The pin assignment is identical to that of the SBP0400 (power supply at the second INJECTOR pin - pin 40). * LCM-1001 base device ($149,95) * LCM-1002 controller module for micro programming with 256×20 bit PROM ($189,95) * LCM-1003 memory module containing 1024 12-bit words ($189,95) * LCM-1004 input/output module ($109,95)

Prototype, successors, and clones

The prototype was given the designation X0400.ntrs.nasa.gov (PDF)
Another circuit family member is the SBP0401 without the operations register and with an asynchronous operation decoder. Bit slice processor successors from TI were the 8-bit SN74AS888 and the 16-bit SBP9900. The former Soviet Union manufactured an SBP0400 Clone, the K582IK2 (К582ИК2).

Sources

Literature

* LCM-1001 handbook * (mirror: ; ) * {{cite book , title=The Bipolar Microcomputer Components Data Book , publisher=Texas Instruments , year=1977 , url=https://archive.org/stream/bitsavers_tidataBookcomputerComponentsDataBook_16851665/1977_TI_Bipolar_Microcomputer_Components_Data_Book#page/n71

References

External links

SBP0400 photographs

Technical data and comparison with other processors (NASA study 1975)
PDF, 9 MB

Texas Instruments hardware Bit-slice chips