docs: updates types.md page

Author: boriel

docs/types.md

@@ -1,6 +1,6 @@
 # Types
 
-## Introductions
+## Introduction
 
 Although ZX BASIC was originally designed with ZX Spectrum in mind, it is a three-stage _retargeable_ compiler. This means it should not be difficult to hack ZX BASIC SDK to compile for other target machines (E.g. Commodore 64) or current machines (PC) or even virtual machines like Java or .NET. Porting ZX BASIC to other Z80 architectures like Amstrad or MSX should be almost straightforward (only the library.asm should need some work to use different ROM routines).
 
@@ -25,14 +25,14 @@ They can be _unsigned_ (their value is always 0 or positive) or _signed_ (can ta
 ZX Basic integer types sizes are 8, 16 and 32 bits. Unsigned types have the prefix _U_.
 
 
-| Type name | Size (bytes) | Signed? | Range | Description |
-|:-----------|:-----:|:--------:|:------:|:-------------|
-| Byte | 1 | yes | -128..127  | 8 bits signed integer  |
-| UByte| 1 | no | 0..255  | 8 bits unsigned integer  |
-| Integer | 2 | yes | -32768..32767 | 16 bits signed integer |
-| UInteger | 2 | no | 0..65535 | 16 bits unsigned integer |
-| Long | 4 | yes |  <small>−2,147,483,648 .. +2,147,483,647</small> | 32 bit signed integer |
-| ULong | 4 | yes | <small>0 .. 4,294,967,295</small>| 32 bit unsigned integer |
+| Type name | Size (bytes) | Signed? |                      Range                      | Description              |
+|:----------|:------------:|:-------:|:-----------------------------------------------:|:-------------------------|
+| Byte      |      1       |   yes   |                    -128..127                    | 8 bits signed integer    |
+| UByte     |      1       |   no    |                     0..255                      | 8 bits unsigned integer  |
+| Integer   |      2       |   yes   |                  -32768..32767                  | 16 bits signed integer   |
+| UInteger  |      2       |   no    |                    0..65535                     | 16 bits unsigned integer |
+| Long      |      4       |   yes   | <small>−2,147,483,648 .. +2,147,483,647</small> | 32 bit signed integer    |
+| ULong     |      4       |   yes   |        <small>0 .. 4,294,967,295</small>        | 32 bit unsigned integer  |
 
 
 ### Decimals
@@ -41,7 +41,7 @@ Their sizes are 32 bit for `Fixed` type and 40 bits for `Float` one.
 
 #### Fixed
 32 bit Fixed Point decimal. First 16 bits are the integer part, whilst remaining 16 contains the decimal one.
-Ranges from -32767.9999847 to 32767.9999847 with a precision of 1 / 2^16 (0.000015 approx.).
+Ranges from `-32767.9999847` to `32767.9999847` with a precision of 1 / 2<sup>16</sup> (0.000015 approx.).
 Fixed points decimal are less precise than Floating ones, but much faster and requires
 less space (1 byte less). Also, their range is much limited.
 They're usually used on screen drawing when Floating point is too slow and decimal
@@ -50,7 +50,8 @@ calculations are required.
 #### Float
 Floating point type is **identical** to the Sinclair BASIC one.
 It requires 5 bytes (1 byte for exponent, 4 bytes for mantissa).
-Read the ZX Spectrum manual or [here](http://www.worldofspectrum.org/ZXBasicManual/zxmanchap24.html).
+Read the [Chapter 24 of the ZX Spectrum manual](http://www.worldofspectrum.org/ZXBasicManual/zxmanchap24.html)
+for further information.
 
 >To store the number in the computer, we use five bytes, as follows:
 >
@@ -75,7 +76,7 @@ At this moment, ZX BASIC is not an <abbr title="Object Oriented Programming">OOP
 Vars are _scalar_ variables. Scalar variables are those which store a single value.
 Almost all variables are scalars:
 
-```
+```basic
 REM A simple scalar variable
 DIM a = 3
 ```
@@ -85,7 +86,7 @@ DIM a = 3
 Unlike scalars, array variables can hold more than a single value at once.
 You access a single value within the array container using an integer _index_:
 
-```
+```basic
 REM An array variable
 DIM a(1 TO 10) AS UBYTE
 LET a(3) = 5: REM pick a(3) cell and store the number 5 in it
@@ -97,7 +98,7 @@ Unlike the above, [labels](labels.md) are not variables.
 They refer to memory positions. Line numbers are also treated as labels and they are completely optional:
 
 
-```
+```basic
 10 REM here '10' is a Label
  5 REM here '5' is another label, so the number order does not matter
    REM Line numbers are optional. So this line is ok either.