Embedded Systems, SIC/XE Architecture, and Assemblers

Vocabulary flashcards covering core concepts of embedded systems, SIC/XE architecture, and assembler design.

Embedded System

An Electronic/Electro-mechanical system designed to perform a specific function, consisting of a combination of hardware and firmware (software).

General Purpose Computing System

A system which is a combination of generic hardware and a General Purpose Operating System (GPOS) for executing a variety of applications.

Apollo Guidance Computer (AGC)

The first recognized modern embedded system.

Autonetics D-17

The guidance computer for the Minuteman-I missile, which was the first mass-produced embedded system.

Data Collection Purpose

An embedded system function designed to acquire continuous (analog) or discrete (digital) data from the external world for storage, analysis, manipulation, or transmission.

Data Processing Purpose

An embedded system functionality employed in applications demanding signal processing, such as speech coding, synthesis, and audio/video codecs.

Monitoring Purpose

An embedded system function used for determining the state of variables using input sensors, without the capability to impose control over variables.

Control Purpose

An embedded system functionality that imposes control over output variables according to changes in measured input variables using both sensors and actuators.

Wearable Devices

Embedded technologies or systems incorporated into accessories and apparels, envisioning the bonding of embedded technology in day-to-day life.

Simplified Instructional Computer (SIC)

A hypothetical computer that includes hardware features most often found on real machines, existing in a standard model and an upward-compatible SIC/XE model.

SIC Memory Architecture

Memory consisting of $8\text{-bit}$ bytes where $3$ consecutive bytes form a $24\text{-bit}$ word, addressed by the lowest-numbered byte, with a total memory size of $2^{15}$ ($32768$) bytes.

Accumulator (Register A)

A $24\text{-bit}$ SIC register with mnemonic $0$, used for arithmetic operations.

Index Register (Register X)

A $24\text{-bit}$ SIC register with mnemonic $1$, used for indexed addressing.

Linkage Register (Register L)

A $24\text{-bit}$ SIC register with mnemonic $2$, where the Jump to Subroutine (JSUB) instruction stores the return address.

Program Counter (Register PC)

A $24\text{-bit}$ SIC register with mnemonic $8$, which contains the address of the next instruction to be fetched for execution.

Status Word (Register SW)

A $24\text{-bit}$ SIC register with mnemonic $9$, containing a variety of control information including a Condition Code (CC).

Base Register (Register B)

An additional $24\text{-bit}$ register in SIC/XE with mnemonic $3$, used for base-relative addressing.

Register S and Register T

General working registers in SIC/XE with mnemonics $4$ and $5$ respectively, used strictly for storing data and not usable as accumulators.

Floating-Point Accumulator (Register F)

A $48\text{-bit}$ register in SIC/XE with mnemonic $6$, used for floating-point arithmetic operations.

SIC Standard Instruction Format

A $24\text{-bit}$ format consisting of an $8\text{-bit}$ opcode, a $1\text{-bit}$ index indication flag ($x$), and a $15\text{-bit}$ address field.

SIC/XE Maximum Memory

An expanded memory architecture supporting a maximum memory size of $1$ megabyte ($2^{20}$ bytes).

Program-Counter Relative Addressing

A SIC/XE relative addressing mode indicated by $b=0, p=1$, where target address is calculated as $\text{TA} = (\text{PC}) + \text{disp}$ using a $12\text{-bit}$ signed 2's complement displacement.

Base Relative Addressing

A SIC/XE relative addressing mode indicated by $b=1, p=0$, where target address is calculated as $\text{TA} = (\text{B}) + \text{disp}$ using a $12\text{-bit}$ unsigned integer displacement ($0 ≤ \text{disp} ≤ 4095$).

Immediate Addressing Mode

A SIC/XE addressing mode indicated by $i=1, n=0$, where the target address value itself is used as the operand without making a memory reference.

Indirect Addressing Mode

A SIC/XE addressing mode indicated by $i=0, n=1$, where the word at the target address is fetched to provide the actual address of the operand.

Assembler Directives

Pseudo-instructions (such as START, END, BYTE, WORD, RESB, RESW) that provide instructions to the assembler itself and are not translated into machine operation codes.

Forward Reference

A reference to a symbolic label in a program that is defined later in the source code.

Pass 1 (Assembler)

The first pass of a two-pass assembler that scans the source program to assign addresses to statements, define symbols, store label addresses in SYMTAB, and process certain directives.

Pass 2 (Assembler)

The second pass of a two-pass assembler that translates operation codes and lookup addresses, generates data values defined by directives, and produces the object program and listing.

OPTAB (Operation Code Table)

A static table (usually implemented as a hash table) used by assemblers to look up mnemonic operation codes, machine language equivalents, instruction formats, and lengths.

SYMTAB (Symbol Table)

A dynamic table (usually implemented as a hash table) used by assemblers to store label names, assigned addresses, types, lengths, and error flag indicators.

LOCCTR (Location Counter)

An assembler variable initialized to the starting address specified in START, updated by instruction/data length to assign memory addresses to labels.

Header Record

An object program record starting with 'H' that contains the program name, starting address, and total length of the object program in bytes.

Text Record

An object program record starting with 'T' containing the starting memory address, byte length, and compiled machine object code.

End Record

An object program record starting with 'E' specifying the end of the object program and the address of the first executable instruction.