Atari 400 Technical Reference Manual page 234

M13 ZTEMP1* [OOF5,2] -- Temporary storage
M14 ZTEMP4* [OOF7,2] -- Temporary storage
M15 ZTEMP3* [OOF9,2] -- Temporary storage
M16 FLPTR [OOFC,2] -- Pointer to FP number
M17 FPTR2* [OOFE,2] -- FP package use
M18 LBPR1* [057E,1] -- LBUFF preamble
M19 LBPR2* [057F,1] -- LBUFF preamble
M20 LBUFF [0580,96] -- Text buffer
M21 PLYARG* [05EO,6] -- FP register (internal)
M22 FPSCR/FSCR* [05E6,6] -- FP register (internal)
M23 FPSCR1/SCR1* [05EC,6] -- FP register (internal)
M24 DEGFLG/RADFLG [OOFS.1] -- Degrees/radians flag
DEGFLG
=
0 indicates radians, 6 indicates degrees.
N. Power-Up and SYSTEM RESET
See Section 7 for details of the power-up and system reset
operations.
RAM Sizing
During power-up and system reset the first non-RAM address above 1000
hex is located and its address retained using a nondestructive
test. The first byte of every 4K memory "block" is tested to see if
it is alterable; if so, the original value is restored and the next
block is tested, and if not, that
addre~s
is considered to be the
end of RAM.
OPERATING SYSTEM C016555 -- Appendix L
249