Pass 1:

Begin

get PROOADDR from operating system

set CSADDR to PROOADDR {for first control section}

while not end of input do

begin

read next input record {Header record for control section}

set CSLTH to control section length

search ESTAB for control section name

if found then

set error flag {duplicate external symbol}

else

enter control section name into ESTAB with value CSADDR

while record type ~ 'E' do

begin

read next input record

if record type = 'D' then

for each symbol in the record do

begin

search ESTAB for symbol name

if found then

set error flag (duplicate external symbol)

else

enter symbol into ESTAB with value(CSADDR + indicated address)

end {for}

end {while ~ 'E'}

add CSLTH to CSADDR {starting address for next control section}

end {while not EOF}

end {Pass 1}

 

The operation of absolute loader is very simple. The object code is loaded to specified locations in the memory. At the end the loader jumps to the specified address to begin execution of the loaded program. The role of absolute loader is as shown in the figure 4.4.

The advantage of absolute loader is simple and efficient. But the disadvantages are, the need for programmer to specify the actual address, and, difficult to use subroutine libraries.

The algorithm for this type of loader is given here. The object program and, the object program loaded into memory by the absolute loader are also shown. Each byte of assembled code is given using its hexadecimal representation in character form. Easy to read by human beings. Each byte of object code is stored as a single byte. Most machine store object programs in a binary form, and we must be sure that our file and device conventions do not cause some of the program bytes to be interpreted as control characters.

Begin

read Header record

verify program name and length

read first Text record

while record type is <> ‘E’ do

begin

{if object code is in character form, convert into internal representation} move object code to specified location in memory read next object program record

end

jump to address specified in End record

end

 

 The Algorithm for Pass 1:

The Algorithm for Pass 2:

 

Program relocation

Ø The actual starting address of the program is not known until load time

Ø An object program that contains the information necessary to perform this kind of modification is called a relocatable program

Ø No modification is needed: operand is using program-counter relative or base relative addressing

Ø The only parts of the program that require modification at load time are those that specified direct (as opposed to relative) addresses

Ø Modification record

        o Col. 2-7 Starting location of the address field to be modified, relative to the           beginning of the program (Hex)

Col. 8-9  Length of the address field to be modified, in half-bytes (Hex)

Sometimes it is required to load and run several programs at the same time. The system must be able to load these programs wherever there is place in the memory. Therefore the exact starting is not known until the load time.

Absolute Program

In this the address is mentioned during assembling itself. This is called Absolute Assembly.

 

Consider the instruction:

55101B  LDA   THREE    00102D

· This statement says that the register A is loaded with the value stored at location 102D. Suppose it is decided to load and execute the program at location 2000 instead of location 1000.

· Then at address 102D the required value which needs to be loaded in the register A is no more available. The address also gets changed relative to the displacement

of the program. Hence we need to make some changes in the address portion of the instruction so that we can load and execute the program at location 2000.

 

· Apart from the instruction which will undergo a change in their operand address value as the program load address changes. There exist some parts in the program which will remain same regardless of where the program is being loaded.

 

· Since assembler will not know actual location where the program will get loaded, it cannot make the necessary changes in the addresses used in the program. However, the assembler identifies for the loader those parts of the program which need modification.

 

· An object program that has the information necessary to perform this kind of modification is called the relocatable program.

 Machine-Dependent Assembler Features:
➜Instruction formats and addressing modes
➜Program relocation.
Instruction formats and Addressing Modes
The instruction formats depend on the memory organization and the size of the memory. In SIC machine the memory is byte addressable. Word size is 3 bytes. So the size of the memory is 2^12 bytes. Accordingly it supports only one instruction format. It has only two registers: register A and Index register. Therefore the addressing modes supported by this architecture are direct, indirect, and indexed. Whereas the memory of a SIC/XE machine is.
220 bytes (1 MB). This supports four different types of instruction types, they are:   1 byte instruction
  2 byte instruction
  3 byte instruction
  4 byte instruction
Instructions can be:


–-- Instructions involving register to register
–-- Instructions with one operand in memory, the other in Accumulator (Single operand instruction)
--– Extended instruction format
Addressing Modes are:
–-- Index Addressing(SIC): Opcode m, x
–-- Indirect Addressing: Opcode @m
–-- PC-relative: Opcode m
--– Base relative: Opcode m
–-- Immediate addressing: Opcode #c
Translations for the Instruction involving Register-Register addressing mode:
During pass 1 the registers can be entered as part of the symbol table itself. The value for these registers is their equivalent numeric codes. During pass2, these values are assembled along with the mnemonics object code. If required a separate table can be created with the register names and their equivalent numeric values.

Translation involving Register-Memory instructions:
In SIC/XE machine there are four instruction formats and five addressing modes. For formats and addressing modes. Among the instruction formats, format -3 and format-4 instructions are Register-Memory type of instruction.
Program relocation
➜The actual starting address of the program is not known until load time
➜An object program that contains the information necessary to perform this kind of modification is called a relocatable program
➜No modification is needed: operand is using program-counter relative or base relative addressing
➜The only parts of the program that require modification at load time are those that specified direct (as opposed to relative) addresses
➜Modification record
 ⦿Col. 2-7 Starting location of the address field to be modified, relative to the beginning of the program (Hex)
➜Col. 8-9 Length of the address field to be modified, in half-bytes (Hex)

Machine independent assembler feature:

Literals
Symbol-defining statements
Expressions
Program block
Control sections and program linking

Literals
 
➤ Write the value of a constant operand as a part of the instruction that uses it Such an operand is called a literal
 
➤ Avoid having to define the constant elsewhere in the program and make up a label for it
 
➤ A literal is identified with the prefix =, which is followed by a specification of the literal value
 
➤ Examples of literals in the statements:

o45	001A	ENDFIL	LDA	=C’EOF’    032010
o215	1062	WLOOP	TD	=X’05’	   E32011 

 
➤ With a literal, the assembler generates the specified value as a constant at some other memory location
 
➤ The address of this generated constant is used as the target address for the machine instruction
 
➤ All of the literal operands used in the program are gathered together into one or more literal pools
 
➤ Normally literals are placed into a pool at the end of the program
 
➤ A LTORG statement creates a literal pool that contains all of the literal operands used since the previous LTORG
 
➤ Most assembler recognize duplicate literals: the same literal used in more than one place and store only one copy of the specified data value
 
➤ LITTAB (literal table): contains the literal name, the operand value and length, and the address assigned to the operand when it is placed in a literal pool

Expressions
 Assembler allow arithmetic expressions formed according to the normal rules using the operator +, -, *, and /
 Individual terms in the expression may be constants, user-defined symbols, or special terms
 The most common such special term is the current value of the location counter (designed by *)
 Expressions are classified as either absolute expressions or relative expressions
Program Block
 Program blocks: segments of code that are rearranged within a single object unit
 Control sections: segments that are translated into independent object program units
 USE indicates which portions of the source program belong to the various blocks
Control section
 References between control sections are called external references
 The assembler generates information for each external reference that will allow the loader to perform the required linking
 The EXTDEF (external definition) statement in a control section names symbol, called external symbols, that are define in this section and may be used by other sections
 The EXTREF (external reference) statement names symbols that are used in this control section and are defined elsewhere
Define record (D)
⦿  Col. 2-7 Name of external symbol defined in this control section
⦿  Col. 8-13 Relative address of symbol within this control section (Hex)
⦿  Col. 14-73 Repeat information in Col. 2-13 for other external symbols
Refer record (R)
⦿  Col. 2-7 Name of external symbol referred to in this control section
⦿  Col. 8-73 Names of other external reference symbols
Modification record (revised : M)
⦿  Col. 2-7 Starting address of the field to be modified, relative to the beginning of the control section (Hex)
⦿  Col. 8-9 Length of the field to be modified, in half-bytes (Hex)
⦿  Col. 10 Modification flag (+ or -)
⦿  Col. 11-16 External symbol whose value is to be added to or subtracted from the indicated field

 Memory:
⦿ Memory consists of 8-bit bytes; any 3 consecutive bytes form a word (24 bits). All addresses on SIC are byte addresses
⦿ Words are addressed by the location of their lowest numbered byte.
⦿ There are total of 32,768 (215) bytes in the computer memory.
Registers:
There are five registers, all of which have special uses. Each register is 24 bits in length. Their mnemonics, numbers and uses are given in the following table.

Mnemonic	Number	Special Use
A	0	Accumulator; used for arithmetic operations
X	1	Index register; used for addressing
L	2	Linkage register; JSUB instruction stores the return address in this register
PC	8	Program counter; contains the address of the next instruction to be fetched for execution.
SW	9	Status word; contains a variety of information, including a Condition Code (CC)

Data Formats:
⦿Integers are stored as 24-bit binary numbers.
⦿2’s complement representation is used for negative values.
⦿characters are stored using their 8-bit ASCII codes.
⦿There is no floating-point hardware on the standard version of SIC.
Instruction Formats: All machine instructions on the standard version of SIC have the 24-bit format:

8	       1	           15
opcode	       x	           Address

Addressing Modes: There are two addressing modes available, indicated by the setting of the x bit in the instruction.

Mode	Indication	Target Address Calculation
Direct	x=0	TA= address
Indexed	x=1	TA= address + (X)

Parentheses are used to indicate the contents of a register or a memory location. For example, (X) represents the contents of register X.
Direct Addressing Mode:

 Example: LDA     TEN		LDA – 00
 opcode	  x	                                 TEN
 0 0 0 0   0 0 0 0	  0	        0 0 1    0 0 0 0    0 0 0 0    0 0 0 0
 Effective Address (EA) = 1000
 Content of the address 1000 is loaded to Accumulator.
 
 

Indexed Addressing Mode:
Example: STCH BUFFER, X

 
 opcode	  x	                          BUFFER
 0 0 0 0   0 1 0 0	  1	        0 0 1    0 0 0 0    0 0 0 0    0 0 0 0

Effective Address (EA) = 1000 + [X] = 1000 + content of the index register X
The Accumulator content, the character is loaded to the Effective address.
Instruction Set:
SIC provides, load and store instructions (LDA, LDX, STA, STX, etc.). Integer arithmetic operations: (ADD, SUB, MUL, DIV, etc.). All arithmetic operations involve register A and a word in memory, with the result being left in the register. Two instructions are provided for subroutine linkage. COMP compares the value in register A with a word in memory, this instruction sets a condition code CC to indicate the result. There are conditional jump instructions: (JLT, JEQ, JGT), these instructions test the setting of CC and jump accordingly. JSUB jumps to the subroutine placing the return address in register L, RSUB returns by jumping to the address contained in register L.
Input and Output:
Input and Output are performed by transferring 1 byte at a time to or from the rightmost 8 bits of register A (accumulator).
The Test Device (TD) instruction tests whether the addressed device is ready to send or receive a byte of data. Read Data (RD), Write Data (WD) are used for reading or writing the data.

 The browser window can be used to display more than one document at a time. The window can be divided into rectangular areas, each of which is a frame. Each frame is capable of displaying its own document.
Framesets:

⇰ The number of frames and their layout in the browser window are specified with the <frameset> tag.
⇰ A frameset element takes the place of the body element in a document. A document has either a body or a frameset but cannot have both.
⇰ The <frameset> tag must have either a rows or a cols attribute. (or both)
⇰ To create horizontal frames, rows attribute is used.
⇰ To create vertical frames, cols attribute is used.
⇰ The values for these attributes can be numbers, percentages and asterisks.
⇰ Two or more values are separated by commas & given in quoted string.
full solution in the Image

 The most common way for a user to communicate information from a Web browser to the server is through a form. XHTML provides tags to generate the commonly used objects on a screen form. These objects are called controls or widgets. There are controls for single-line and multiple-line text collection, checkboxes, radio buttons, and menus, among others. All control tags are inline tags.
The <form> Tag:
All of the controls of a form appear in the content of a <form> tag. A block tag, <form>, can have several different attributes, only one of which, action, is required. The action attribute specifies the URL of the application on the Web server that is to be called when the user clicks the <i> Submit button</i>. Our examples of form elements will not have corresponding application programs, so the value of their action attributes will be the empty string (""). The <input> Tag: Many of the commonly used controls are specified with the inline tag <input>, including those for text, passwords, checkboxes, radio buttons, and the action buttons Reset, Submit, and plain.
Text Box

• It is a type of input which takes the text.
• Any type of input can be created using <input>
• The type attribute indicates what type of input is needed for the text box, the value should be given as text.
• For any type of input, a name has to be provided which is done using name attribute.
• The size of the text can be controlled using size attribute.
• Every browser has a limit on the number of characters it can collect. If this limit is exceeded, the extra characters are chopped off. To prevent this chopping, maxlength attribute can be used. When maxlength is used, users can enter only those many characters that is given as a value to the attribute.

<html>
<head>
<title>Text Box</title>
</head>
<body>
<form action = " ">
<p> <label>Enter your Name:
<input type = "text" name = "myname" size = "20" maxlength = "20" />
</label> </p>
</form>
</body>
</html>

Password Box

• If the contents of a text box should not be displayed when they are entered by the user, a password control can be used.
• In this case, regardless of what characters are typed into the password control, only bullets or asterisks are displayed by the browser.

<html>
<head>
<title>Password Box</title>
</head>
<body>
<form action = " ">
<p> <label>Enter the email id:
<input type = "text" name = "myname" size = "24" maxlength = "25" /> </label> </p>
<p> <label>Enter the password:
<input type = "password" name = "mypass" size = "20" maxlength = "20" />
</label> </p>
</form>
</body>
</html>

Radio Button

• Radio buttons are special type of buttons which allows the user to select only individual option
• Radio buttons are created using the input tag with the type attribute having the value radio.
• When radio buttons are created, values must be provided with the help of value attribute.
• All the radio buttons which are created would have same name. This is because the radio buttons are group elements.
• If one of the radio buttons has to be selected as soon as the web page is loaded, checked attribute should be used. The value also would be checked.

<html>
<head>
<title>Radio Button</title>
</head>
<body>
<h3>Age Category ?</h3>
<form action = " ">
<p>
<label><input type="radio" name="age" value="under20" checked = “checked”/>0-19 </label>
<label><input type="radio" name="age" value="20-35"/>20-35</label>
<label><input type="radio" name="age" value="36-50"/>36-50 </label>
<label><input type="radio" name="age" value=" over50"/>over50</label>
</p>
</form>
</body>
</html>

Check Box

• Check box is a type of input using which multiple options can be selected.
• Check box can also be created using the <input> tag with the type having the value “checkbox”.
• During the creation of check box, the value should be provided using the value attribute.
• All the checkbox which are created would have the same name because they are group elements.
• If one of the check box have to be selected as soon as the page is loaded, checked attribute should be used with the value checked.

<html>
<head>
<title>Check Box</title>
</head>
<body>
<h3>Grocery Checklist</h3>
<form action = " ">
<p>
<label><input type="checkbox" name="groceries" value="milk" checked=”checked”/>Milk</label>
<label><input type="checkbox" name=" groceries" value="bread"/> Bread </label>
<label><input type="checkbox" name=" groceries" value="eggs"/>Eggs</label>
</p>
</form>
</body>
</html>

The <select> Tag:

• Menu items is another type of input that can be created on the page.
• To create the menu item, <select> tag is used.
• To insert the item in the menu, <option> tag is used.

<html>
<head>
<title> Menu </title>
</head>
<body>
<p> ATME Branches - Information Science, Computer Science, Electronics, Electrical, Mechanical </p>
<form action = "">
<p> With size = 1 (the default)
<select name = "branches">
<option> Information Science </option>
<option> Computer Science </option>
<option> Electronics </option>
<option> Electrical </option>
<option> Mechanical </option>
</select>
</p>
</form>
</body>
</html>

If you give <select name = "branches" size = “3”>, then you will get a scroll bar instead of drop down menu. It is as shown in the output given below:
The <textarea> Tag:

• Text area is a type of input using which multiple statements can be entered.
• Text area is created using <textarea> tag.
• Text area should have the name.
• During the creation of text area, it should be mentioned how many sentences can be entered. This is done using rows attribute.
• Similarly, it should also be mentioned how many characters can be entered in a line. This is done using cols attribute.
• If the value given to rows is exceeded i.e. if users enter sentences more than specified, the scroll bar automatically appears.

<html>
<head>
<title> text area </title>
</head>
<body>
<form action=" ">
<h3> Enter your comments</h3>
<p>
<textarea name="feedback" rows="5" cols="100">
(Be Brief and concise)
</textarea>
</p>
</form>
</body>
</html>

The Action Buttons:
The Reset button clears all of the controls in the form to their initial states. The Submit button has two actions: First, the form data is encoded and sent to the server; second, the server is requested to execute the server-resident program specified in the action attribute of the <form> tag. The purpose of such a server-resident program is to process the form data and return some response to the user. Every form requires a Submit button. The Submit and Reset buttons are created with the <input> tag.

<html>
<head>
<title> action buttons </title>
</head>
<body>
<form action=" ">
<p>
<input type="SUBMIT" value="SUBMIT"/>
<input type="RESET" value="RESET"/>
</p>
</form>
</body>
</html>

Example of a Complete Form:

<html>
<head>
<title> CompleteForm</title>
</head> <body>
<h1>Registration Form</h1>
<form action=" ">
<p> <label>Enter your email id:
<input type = "text" name = "myname" size = "24" maxlength = "25" />
</label> </p>
<p> <label>Enter the password:
<input type = "password" name = "mypass" size = "20" maxlength = "20" />
</label> </p>
<p>Sex</p>
<p>
<label><input type="radio" name="act" value="one"/>Male</label>
<label><input type="radio" name="act" value="two"/>Female</label>
</p>
<p>Which of the following Accounts do you have?</p>
<p>
<label><input type="checkbox" name="act" value="one"/>Gmail</label>
<label><input type="checkbox" name="act" value="two"/>Facebook</label>
<label><input type="checkbox" name="act" value="three"/>Twitter</label>
<label><input type="checkbox" name="act" value="four"/>Google+</label>
</p>
<p> Any Suggestions?</p>
<p> <textarea name="feedback" rows="5" cols="100"> </textarea> </p>
<p>Click on Submit if you want to register</p>
<p> <input type="SUBMIT" value="SUBMIT"/>
<input type="RESET" value="RESET"/>
</p>
</form>
</body>
</html>

 A table is a matrix of cells. The cells in the top row often contain column labels, those in the leftmost column often contain row labels, and most of the rest of the cells contain the data of the table. The content of a cell can be almost any document element, including text, a heading, a horizontal rule, an image, and a nested table.
Basic Table Tags
➤A table is specified as the content of the block tag <table>.
➤There are two kinds of lines in tables: the line around the outside of the whole table is called the border; the lines that separate the cells from each other are called rules.
➤It can be obtained using border attribute. The possible values are “border” or any number.
➤The table heading can be created using <caption> tag.
➤The table row can be created using <tr> tag.
➤The column can be created either by using <th> tag (stands for table header which is suitable for headings) or <td> tag (stands for table data which is suitable for other data).

<html>
<head>
<title> Table with text and image </title>
</head>
<body>
<table border = "border">
<caption>VTU Memo </caption>
<tr>
<th> VTU </th>
<th> Image </th>
</tr>
<tr>
<td> Funny image </td>
<td> <img src = "img(13).jpg" alt = "cant display"/></td>
</tr>
<tr>
<td> True Story </td>
<td> <img src = "img(19).jpg" alt = "cant display"/></td>
</tr>
</table>
</body>
</html>

The rowspan and colspan Attributes: Multiple-level labels can be specified with the rowspan and colspan attributes.

<html>
<head>
<title>row-span and column-span</title>
</head>
<body>
<p> Illustration of Row span</p>
<table border="border">
<tr>
<th rowspan="2"> ATME</th>
<th>ISE</th>
</tr>
<tr>
<th>CSE</th>
</tr>
</table>
<p> Illustration of Column span</p>
<table border="border">
<tr>
<th colspan="2"> ATME </th>
</tr>
<tr>
<th>ISE</th>
<th>CSE</th>
</tr>
</table>
</body>
</html>

The align and valign Attributes:

➤The placement of the content within a table cell can be specified with the align and valign attributes in the <tr>, <th>, and <td> tags.
➤The align attribute has the possible values left, right, and center, with the obvious meanings for horizontal placement of the content within a cell.
➤The default alignment for th cells is center; for td cells, it is left. The valign attribute of the <th> and <td> tags has the possible values top and bottom.
➤The default vertical alignment for both headings and data is center.

<html>
<head>
<title> Align and valign </title>
</head>
<body>
<p>Table having entries with different alignments</p>
<table border="border">
<tr align = "center">
<th> </th>
<th> Column Label </th>
<th> Another One </th>
<th> Still Another </th>
</tr>
<tr>
<th> Align </th>
<td align = "left"> Left</td>
<td align = "center"> Center </td>
<td align = "right"> right </td>
</tr>
<tr>
<th> <br/>Valign<br/><br/><br/></th>
<td> Deafult </td>
<td valign = "top"> Top</td>
<td valign = "bottom"> Bottom</td>
</tr>
</table>
</body>
</html>

The cellpadding and cellspacing Attributes:
Cellspacing is the distance between cells. Cellpadding is the distance between the edges of the cell to its content.

<html>
<head>
<title> cell spacing and cell padding </title>
</head>
<body>
<h3>Table with space = 10, pad = 50</h3>
<table border = "7" cellspacing = "10" cellpadding = "50">
<tr>
<td> Kswamy</td>
<td>Chethan </td>
</tr>
</table>
<h3>Table with space = 50, pad = 10</h3>
<table border = "7" cellspacing = "50" cellpadding = "10">
<tr>
<td> Divya </td>
<td>Chethan </td>
</tr>
</table>
</body>
</html>

Table Sections:

➤ Tables naturally occur in two and sometimes three parts: header, body, and footer. (Not all tables have a natural footer.)
➤ These three parts can be respectively denoted in XHTML with the thead, tbody, and tfoot elements.
➤ The header includes the column labels, regardless of the number of levels in those labels.
➤ The body includes the data of the table, including the row labels.
➤ The footer, when it appears, sometimes has the column labels repeated after the body.
➤ In some tables, the footer contains totals for the columns of data above.
➤ A table can have multiple body sections, in which case the browser may delimit them with horizontal lines that are thicker than the rule lines within a body section.

 Unordered Lists: The <ul> tag, which is a block tag, creates an unordered list. Each item in a list is specified with an <li> tag (li is an acronym for list item). Any tags can appear in a list item, including nested lists. When displayed, each list item is implicitly preceded by a bullet.

<html>
<head>
<title> Unordered List </title>
</head>
<body>
<h1> Some Common Single-Engine Aircraft </h1>
<ul>
<li> Cessna skyhawk</li>
<li> Beechcraft Bonaza</li>
<li> piper Cherokee</li>
</ul>
</body>
</html>

Ordered Lists:
✦ Ordered lists are lists in which the order of items is important. This orderedness of a list is shown in the display of the list by the implicit attachment of a sequential value to the beginning of each item. The default sequential values are Arabic numerals, beginning with 1. An ordered list is created within the block tag <ol>.
✦ The items are specified and displayed just as are those in unordered lists, except that the items in an ordered list are preceded by sequential values instead of bullets.
<html>
<head>
<title> ordered List </title>
</head>
<body>
<h3> Cessna 210 Engine Starting Instructions </h3>
<ol>
<li> Set mixture to rich </li>
<li> Set propeller to high RPM </li>
<li> Set ignition switch to "BOTH" </li>
<li> Set auxiliary fuel pump switch to "LOW PRIME" </li>
<li> When fuel pressure reaches 2 to 2.5 PSI, push starter button </li>
</ol>
</body>
</html>

Nested Lists:
<html>
<head>
<title> nested lists </title>
</head>
<ol>
<li> Information Science </li>
<ol>
<li>OOMD</li>
<li>Java & J2ee</li>
<ul>
<li>classes and methods</li>
<li>exceptions</li>
<li>applets</li>
<li>servelets</li>
</ul>
<li>Computer Networks</li>
<ul>
<li>Part 1</li>
<li>Part 2</li>
</ul>
<li>DBMS</li>
<li>Operations Research</li>
</ol>
<li> Computer Science</li>
<ol>
<li>Compiler Design</li>
<li>FLAT</li>
<ul>
<li>NFA</li>
<li>DFA</li>
<li>CFG</li>
</ul>
<li>Computer Graphics</li>
<li>Artificial Intelligence</li>
</ol>
</ol>
</html>

Definition Lists: ✦As the name implies, definition lists are used to specify lists of terms and their definitions, as in glossaries. A definition list is given as the content of a <dl> tag, which is a block tag.
✦ Each term to be defined in the definition list is given as the content of a <dt> tag. The definitions themselves are specified as the content of $lt;dd> tags.
✦ The defined terms of a definition list are usually displayed in the left margin; the definitions are usually shown indented on the line or lines following the term.
<html>
<head>
<title> Definition List </title>
</head>
<body> <h3> Single-Engine Cessna Airplanes </h3>
<dl >
<dt> 152 </dt>
<dd> Two-place trainer </dd>
<dt> 172 </dt>
<dd> Smaller four-place airplane </dd>
<dt> 182 </dt>
<dd> Larger four-place airplane </dd>
<dt> 210 </dt>
<dd> Six-place airplane - high performance
</dd>
</dl>
</body>
</html>
luding nested lists. When displayed, each list item is implicitly preceded by a bullet. <html> <head> <title> Unordered List </title> </head> <body> <h1> Some Common Single-Engine Aircraft </h1> <ul> <li> Cessna skyhawk</li> <li> Beechcraft Bonaza</li> <li> piper Cherokee</li> </ul> </body> </html>