Memory Maps

VDP Memory Map

In 80x30 F18A mode, Force Command utilizes extended color attributes, and some fast scroll code for the F18A.

Address	Size in bytes	Description
0x0000	0x0960	Image table
0x0960	0x00A0	/free space-------/
0x0A00	0x0100	Sprite table
0x0800	0x0800	Sprite patterns
0x1000	0x0800	Pattern table
0x1800	0x0960	Color attributes
0x2160	varies	/free stack ------/
0x3FF8	0x0008	Nanopeb stats
0x4000	0x0034	Fast scroll routine

Note: sprite pattern overlaps with sprite table, and image table. You can use the tail end of the sprite pattern without conflict. Table entries 20 - 39 and 60 - 255 may be used.

Depending on your disk devices, there may be VDP stack allocations from 0x4000 downward.

In 40 Column mode:

Address	Size in bytes	Description
0x0000	0x03C0	Image table
0x03C0	0x0440	/free space-------/
0x0800	0x0800	Pattern table
0x1000	varies	/free stack ------/
0x3FF8	0x0008	Nanopeb stats
0x4000	0x0034	Fast scroll routine

9938/58 80x26.5 mode:

Address	Size in bytes	Description
0x0000	0x0870	Image table
0x0870	0x0790	/free space-------/
0x1000	0x0800	Pattern table
0x1800	varies	/free stack ------/
0x3FF8	0x0008	Nanopeb stats
0x4000	0x0034	Fast scroll routine

IO Buffers

• lvl2 IO buffer and IO buffer merge -> IO buffer
• IO Buffer holds 17 sectors or 0x1100 bytes.
• locations are common for 40 and 80 column modes.

Address	Size in bytes	Description
0x2160	0x010A	PAB
0x2300	0x0100	IO name buffer
0x2400	0x1100	IO Buffer
0x3500	0x0100	redo buffer
0x3600	varies	/free stack ------/

Note: VDP RAM redo buffer is only used if no SAMS is present

CPU RAM Memory Map

Force Command resides in Cartridge ROM space and the RAM usage varies if SAMS is present.

32K Systems:

Address	Size in bytes	Description
0x2000	0x0400	System global variables
0x2400+	varies	Environment Variables
-0x3FFF	varies	System stack
0xA000	90(temporary)	command line edit buffer
0xA000	varies	executable space

If SAMS is available, then a 4K page is used at 0xA000 for command history. This is paged out when executables are loaded. Also when SAMS is available, executables are loaded into SAMS pages sequentially. Additional SAMS pages may be allocated by the executable.

SAMS page map:

Page	Address	Purpose
0	0x2000	Force Command runtime data
1	0x3000	Force Command stack
2,3	0xB000-0xCFFF	command history
4	0xA000	command line edit buffer
4-9	0xA000-0xFFFF	ED file buffer
4+	0xA000	executable space

The command line editor, and ED command free their pages when not active. The command line editor is not active between pressing ENTER and prompting again for another command.

Note, when the LOAD, FG99, or XB commands are used to run a legacy EA5 program, the standard SAMS mapping is set.

EA5 SAMS map:

Page	Address
2	0x2000
3	0x3000
10	0xA000
11	0xB000
12	0xC000
13	0xD000
14	0xE000
15	0xF000