None

No highlighting.

Display file

Highlights the area of memory where the display is kept. This does not include the Attributes region - just the raw bitmap of the display, which consists of 6,144 bytes. (See The .scr file format.)

Attributes

The attributes area contains the colours used to make up the display file. This can best be described as a transparent "overlay" which sits on top of the display, and is 768 bytes long.

Printer buffer

The printer buffer is used by the ZX printer accessory as a holding region for data that is being sent to the printer. It is also used by some programs as a temporary, but well protected area in which you can store small machine code routines. It is 256 bytes in size.

System variables

The System variables occupy 186 bytes, and contain flags and information used by the ROM to handle the BASIC and some other functions such as timekeeping and the display - the PRINT locations, and the coordinates last used by PLOT and DRAW, for example. These variables are discussed in more detail in Chapter 25 of the Spectrum Manual found elsewhere in this help file.

Channels

The channels area of memory contains a list of any channels opened by BASIC to either the screen, the keyboard, the printer, or other I/O devices. The channels region usually occupies only 34 bytes, but this can be extended by moving the PROG system variable to point higher up in memory, which will relocate your BASIC program.

BASIC program

This is the region of memory occupied by your program, after it has been tokenised and stored by the ROM. This area changes in size quite readily, as you edit your program.

Variables

The variables area begins at the address specified in the VARS system variable, and extends to incorporate all the variables used by your program.

Edit line

The Edit Line region of memory stores the user's keystrokes in an INPUT command. This region of memory is also used by the ROM when the user edits a line on the original hardware, but BasinC has removed this necessity by replacing the ROM editor with a newer editor.

Workspace

The workspace is a temporary holding area used for various operations like shuffling variables in expressions around, and other such things.

Calculator stack

The Calculator Stack is where the internal calculator stores it's decoded expressions and performs calculations as part of the ROM calculator.

Spare RAM

The Spare RAM is the (usually empty) space between the Machine stack and the calculator stack. As the Machine stack grows (due to heavy recursion or calculation) it will gradually fill this RAM from top to bottom. As it then recovers RAM and "shrinks", it will not clear the RAM as it goes. You can use the Clear button to do this - it's purely cosmetic.

Note: Use this button with care - if you have machine code or data stored below RAMTOP, you will lose it. Always issue a CLEAR to reserve space for your important memory areas.

Machine stack

This is the region of memory pointed to by the Z80 Register SP. Note that this is likely to grow downward from RAMTOP, and as such any sensitive data stored in memory should not be stored lower than this.

GO SUB stack

The GO SUB stack stores line and statement numbers used as return addresses for subroutines in BASIC. It can get very large very quickly especially when a subroutine calls itself recursively.

UDGs

The UDGs are a list of 21 "characters" which are available to the user, for the purpose of creating your own graphics or symbols to be used in BASIC programs. For more on their use, see Chapter 14 of the Sinclair BASIC Manual, and also under the documentation of the UDG/CHARSET Editor Window. This region is normally 168 bytes in size, but altering the UDG system variable can change that.