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glossary [2016/05/27 16:00]
ex_writer 		glossary [2016/06/05 16:15] (current)
ex_writer [B]
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 **Accumulator**:​ A temporary register where results of calculations may be stored by the central processor. (SC:325) **Accumulator**:​ A temporary register where results of calculations may be stored by the central processor. (SC:325)
 +
 +**Arithmetic and Logic Unit (ALU)**: The circuitry that performs manipulations on data held in the accumulator. (BS:17)
  
 **Assembler**:​ A program that converts symbolic instructions into machine macro-instructions. (SC:325) **Assembler**:​ A program that converts symbolic instructions into machine macro-instructions. (SC:325)
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 === B === === B ===
  
-**BCD**:+**Binary-coded decimal (BCD)**: "A class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight."​ The Bally Arcade uses packed BCD, meaning that each nibble of a byte holds a decimal digit between 0–9 (e.g., $36 = 37D). Numbers between $A–F are considered invalid. ([[wp>​Binary-coded decimal]])
  
 **Bootstrap**:​ A program that coordinates the minimum amount of necessary peripherals to load a larger program into the computer. (SC:113) **Bootstrap**:​ A program that coordinates the minimum amount of necessary peripherals to load a larger program into the computer. (SC:113)
  
 **Bounce**: Move back and forth between states before reaching a final state. Usually refers to mechanical switches that do not open or close cleanly, but rather move back and forth between positions for a while before settling down. (LV:467) **Bounce**: Move back and forth between states before reaching a final state. Usually refers to mechanical switches that do not open or close cleanly, but rather move back and forth between positions for a while before settling down. (LV:467)
 +
 +**Bus**: A group of wires that carry related binary signals, usually a word, as in a 16-wire address bus. A bus can be bidirectional,​ e.g., a data bus. (BS:17)
  
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 **Debounce**:​ Convert the output from a contact with bounce into a single clean transition between states. Debouncing is most commonly applied to outputs from mechanical keys or switches that bounce back and forth before settling into their final positions. (LV:470) **Debounce**:​ Convert the output from a contact with bounce into a single clean transition between states. Debouncing is most commonly applied to outputs from mechanical keys or switches that bounce back and forth before settling into their final positions. (LV:470)
 +
 +**Decoder**:​ Typically a device that detects a specific address on the address bus. (BS:17)
  
 **Directives**:​ Special orders given by the programmer to the assembler that result either in storing values into symbols or into the memory, or in controlling the execution or printing modes of the assembler. (RZ:596) **Directives**:​ Special orders given by the programmer to the assembler that result either in storing values into symbols or into the memory, or in controlling the execution or printing modes of the assembler. (RZ:596)
  
 **Dope vector**: **Dope vector**:
-"A data structure used to hold information about a data object, e.g. an array, especially its memory layout...The dope vector includes an identifier, a length, a parent address, and a next child address."​\\ **Source:​** ​[[wp>​Dope vector]]+"A data structure used to hold information about a data object, e.g. an array, especially its memory layout...The dope vector includes an identifier, a length, a parent address, and a next child address." ​([[wp>​Dope vector]])
  
 ---- ----
-=== E === 
  
-**Endian**: 
- 
----- 
 === F === === F ===
  
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 **Flag**: A bit attached to a word for identification or for the purpose of signaling some condition. Typical microprocessors include carry, zero, sign, overflow, and half-carry status flags. (SC:326) **Flag**: A bit attached to a word for identification or for the purpose of signaling some condition. Typical microprocessors include carry, zero, sign, overflow, and half-carry status flags. (SC:326)
  
-**Framebuffer**:​ +**Framebuffer**:​ A framebuffer (frame buffer, or sometimes framestore) is a portion of RAM[1] containing a bitmap that is driven to a video display from a memory buffer containing a complete frame of data. ([[wp>​Framebuffer]])
-"A framebuffer (frame buffer, or sometimes framestore) is a portion of RAM[1] containing a bitmap that is driven to a video display from a memory buffer containing a complete frame of data."\\ **Source:​** ​[[wp>​Framebuffer]]+
  
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 === P === === P ===
 +
 +**Pattern**:​ A contiguous series of bits that represent picture elements comprising an onscreen image (i.e., graphic).
  
 **Pointer**:​ A storage place that contains the address of a data item rather than the item itself. A pointer tells where the item is located. (LV) **Pointer**:​ A storage place that contains the address of a data item rather than the item itself. A pointer tells where the item is located. (LV)
 +
 +**Port**: A place through which inputs and outputs—either data or instructions—are channeled. A microprocessor can have more than one port or can address many. (BS:18)
  
 **Program counter (PC)**: Contains a 16-bit address in memory from which the current instruction will be fetched. Following execution of the instruction,​ the PC counter is either incremented,​ if the program is to proceed to the next byte in memory, or the present PC contents are replaced with a new value, if a jump or call instruction is to be executed. (SC:28) **Program counter (PC)**: Contains a 16-bit address in memory from which the current instruction will be fetched. Following execution of the instruction,​ the PC counter is either incremented,​ if the program is to proceed to the next byte in memory, or the present PC contents are replaced with a new value, if a jump or call instruction is to be executed. (SC:28)
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 === R === === R ===
  
-**Reentrant**:​ +**Reentrant**: ​A computer program or subroutine ​that can be interrupted in the middle of its execution and then safely called again ("​re-entered"​) before its previous invocations complete execution. ​([[wp>​Reentrancy (computing)]])
-"In computing, a computer program or subroutine ​is called reentrant if it can be interrupted in the middle of its execution and then safely called again ("​re-entered"​) before its previous invocations complete execution."\\ **Source:​** ​[[wp>​Reentrancy (computing)]]+
  
 **Register**:​ A memory device directly accessible by the central processor used for the temporary storage of a computer word during arithmetic, logical, or I/O operations. (SC:​327–8) **Register**:​ A memory device directly accessible by the central processor used for the temporary storage of a computer word during arithmetic, logical, or I/O operations. (SC:​327–8)
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 === S === === S ===
  
-**Scratchpad**:​+**Scratchpad**: ​An area of main memory set aside for short and frequently-used calculations. (BS:18)
  
-**Semaphore**:​ +**Semaphore**:​ A variable or abstract data type used for controlling access, by multiple processes, to a common resource in a concurrent system such as a multiprogramming operating system. A trivial semaphore is a plain variable that is changed (for example, incremented or decremented,​ or toggled) depending on programmer-defined conditions. The variable is then used as a condition to control access to some system resource. ​([[wp>​Semaphore (programming)]])
-"A variable or abstract data type used for controlling access, by multiple processes, to a common resource in a concurrent system such as a multiprogramming operating system. A trivial semaphore is a plain variable that is changed (for example, incremented or decremented,​ or toggled) depending on programmer-defined conditions. The variable is then used as a condition to control access to some system resource."\\ **Source:​** ​[[wp>​Semaphore (programming)]]+
  
 **Stack**: A reserved area of several memory locations, the top of which is indicated by the contents of the stack pointer. Memory location are organized as a last-in, first-out file. By looking at particular entries in the stack, the central processor returns to a main program regardless of the depth of nested subroutines. (SC: 28-9) **Stack**: A reserved area of several memory locations, the top of which is indicated by the contents of the stack pointer. Memory location are organized as a last-in, first-out file. By looking at particular entries in the stack, the central processor returns to a main program regardless of the depth of nested subroutines. (SC: 28-9)
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 **Strobe**: A signal that identifies or describes another set of signals and can be used to control a buffer, latch, or register. (LV:484) **Strobe**: A signal that identifies or describes another set of signals and can be used to control a buffer, latch, or register. (LV:484)
  
----- +**Subroutine**:​ A program within a program that performs a specific, often-used function. (BS:18)
-=== T ===+
  
 ---- ----
-=== U ===+=== V ===
  
----- +**Vector** (1): A data structure consisting of a collection of elements. 
-=== V ===+ 
 +**Vector** (2): A quantity having direction as well as magnitude, especially for determining an object'​s position in space.
  
-**Vector**:+**Vector** ​(3): A specific address loaded into a microprocessor'​s program counter to force the microprocessor to start processing at a specific address. (BS:18)
  
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 **References**:  ​ **References**:  ​
  
 +  * (BS) = Bally Service Manual
   * (LV) = Leventhal, //Z80 Assembly Language Programming//​ ()   * (LV) = Leventhal, //Z80 Assembly Language Programming//​ ()
   * (SC) = Ciarcia, Steve, //Build Your Own Z80 Computer// (1981) ([[https://​books.google.com/​books?​id=mVQnFgWzX0AC|Google Books]])   * (SC) = Ciarcia, Steve, //Build Your Own Z80 Computer// (1981) ([[https://​books.google.com/​books?​id=mVQnFgWzX0AC|Google Books]])
   * (RZ) = Zaks, Rodney, //​Programming the Z80// (1981)   * (RZ) = Zaks, Rodney, //​Programming the Z80// (1981)