From https://emma02.hobby-site.com/elf2_math.html May 20 2025
Also has hardware I/O features and other software/hardware information.
This document is slightly edited for clarity by Herb Johnson

BASIC System Parameters

The last RAM page (top of RAM) is used for BASIC System parameters.

The second last page (and lower if needed) is used for variable and string storage. There is no fixed place for anything. RAM is filled from top down, variables name and first digit have bit 7 set.

[The BASIC program is stored from the bottom of RAM and up, from just above the ROMS at 2006H.
So the program rises from bottom RAM and program variables "sink" from the top of RAM.] 

For details about the last page, see table below. Note that these are my guesses and are potentially incorrect. xx indicates the high byte of the last RAM page, yy the high byte of the second last RAM page.

xx01 - xx02 	End location BASIC variables (0xyyFF).
xx03 - xx04 	End location BASIC variables (0xyyFF).
xx05 - xx06 	Start location BASIC program (0x2006).
xx07 - xx08 	Start location terminal input buffer (0xxx70)
xx09 	0x49 (300 baud), measured input baud rate code.
xx0A 	0x4B (300 baud), measured output baud rate code.
xx0B - xx0C 	End location BASIC variables (0xyyFF).
xx0D - xx0E 	End location BASIC program.
xx20 	0x49 (300 baud), user defined (via SET K) input baud rate code.
xx21 	0x4B (300 baud), user defined (via SET P) output baud rate code.
xx22 - xx23 	Copy of start location terminal input buffer (0xxx70).
xx26 - xx27 	Start location BASIC variables.
xx28 - xx29 	Copy of start location terminal input buffer (0xxx70).
xx36 	Cursor line position counter (1 is left most position).
xx37 	0x18 or 0x37 (selecting line width 32 or 64, set on startup).
xx42 - xx4F 	Calculation result digits.
xx42 	RPN format for sign, bit 3 = 1 indicates negative mantissa, bit 1 = 1 indicates negative exponent.
xx43 	RPN digital point number.
xx44 - xx4F 	Rest of the result, in text format, repeating signs like minus (-), digital point (.) and exponent (E).
xx62 - xx66 	‘00000’ - probably used for the BREAK line number.
xx67 - xx6A 	‘0000’ - used for the CONDITION error code number.
xx70 - xxB7 	Terminal input buffer.
xxB8 - xxBA 	‘;’ a semicolon followed by a return and new line code.
xxBB - xxBD 	‘:’ a colon followed by a return and new line code.
xxBE - xxC2 	‘WHAT’ followed by a return code (used as error message in BASIC input).
xxC3 - xxC4 	0x8A followed by a new line code.
xxC5 - xxD1 	‘CONDITION #’ followed by 0xA0 and a return code (used as error message, 0xA0 will be replaced by an error number).
xxD2 - xxD8 	‘BREAK n’ followed by 0xA0/0xEE (used when break where n is the line number).
xxD9 - xxFF 	Reserved for stack.