HI all,
Does anyone have a correct and complete list of available page 0 locations for EhBasic 2.22?
Page 0 available locations
Re: Page 0 available locations
Code: Select all
00045 ; zero page use ..
00046
00047 0000 LAB_WARM = $00 ; BASIC warm start entry point
00048 0001 Wrmjpl = LAB_WARM+1; BASIC warm start vector jump low byte
00049 0002 Wrmjph = LAB_WARM+2; BASIC warm start vector jump high byte
00050
00051 000A Usrjmp = $0A ; USR function JMP address
00052 000B Usrjpl = Usrjmp+1 ; USR function JMP vector low byte
00053 000C Usrjph = Usrjmp+2 ; USR function JMP vector high byte
00054 000D Nullct = $0D ; nulls output after each line
00055 000E TPos = $0E ; BASIC terminal position byte
00056 000F TWidth = $0F ; BASIC terminal width byte
00057 0010 Iclim = $10 ; input column limit
00058 0011 Itempl = $11 ; temporary integer low byte
00059 0012 Itemph = Itempl+1 ; temporary integer high byte
00060
00061 0011 nums_1 = Itempl ; number to bin/hex string convert MSB
00062 0012 nums_2 = nums_1+1 ; number to bin/hex string convert
00063 0013 nums_3 = nums_1+2 ; number to bin/hex string convert LSB
00064
00065 005B Srchc = $5B ; search character
00066 005B Temp3 = Srchc ; temp byte used in number routines
00067 005C Scnquo = $5C ; scan-between-quotes flag
00068 005C Asrch = Scnquo ; alt search character
00069
00070 005B XOAw_l = Srchc ; eXclusive OR, OR and AND word low byte
00071 005C XOAw_h = Scnquo ; eXclusive OR, OR and AND word high byte
00072
00073 005D Ibptr = $5D ; input buffer pointer
00074 005D Dimcnt = Ibptr ; # of dimensions
00075 005D Tindx = Ibptr ; token index
00076
00077 005E Defdim = $5E ; default DIM flag
00078 005F Dtypef = $5F ; data type flag, $FF=string, $00=numeric
00079 0060 Oquote = $60 ; open quote flag (b7) (Flag: DATA scan; LIST quote; memory)
00080 0060 Gclctd = $60 ; garbage collected flag
00081 0061 Sufnxf = $61 ; subscript/FNX flag, 1xxx xxx = FN(0xxx xxx)
00082 0062 Imode = $62 ; input mode flag, $00=INPUT, $80=READ
00083
00084 0063 Cflag = $63 ; comparison evaluation flag
00085
00086 0064 TabSiz = $64 ; TAB step size (was input flag)
00087
00088 0065 next_s = $65 ; next descriptor stack address
00089
00090 ; these two bytes form a word pointer to the item
00091 ; currently on top of the descriptor stack
00092 0066 last_sl = $66 ; last descriptor stack address low byte
00093 0067 last_sh = $67 ; last descriptor stack address high byte (always $00)
00094
00095 0068 des_sk = $68 ; descriptor stack start address (temp strings)
00096
00097 ; = $70 ; End of descriptor stack
00098
00099 0071 ut1_pl = $71 ; utility pointer 1 low byte
00100 0072 ut1_ph = ut1_pl+1 ; utility pointer 1 high byte
00101 0073 ut2_pl = $73 ; utility pointer 2 low byte
00102 0074 ut2_ph = ut2_pl+1 ; utility pointer 2 high byte
00103
00104 0071 Temp_2 = ut1_pl ; temp byte for block move
00105
00106 0075 FACt_1 = $75 ; FAC temp mantissa1
00107 0076 FACt_2 = FACt_1+1 ; FAC temp mantissa2
00108 0077 FACt_3 = FACt_2+1 ; FAC temp mantissa3
00109
00110 0076 dims_l = FACt_2 ; array dimension size low byte
00111 0077 dims_h = FACt_3 ; array dimension size high byte
00112
00113 0078 TempB = $78 ; temp page 0 byte
00114
00115 0079 Smeml = $79 ; start of mem low byte (Start-of-Basic)
00116 007A Smemh = Smeml+1 ; start of mem high byte (Start-of-Basic)
00117 007B Svarl = $7B ; start of vars low byte (Start-of-Variables)
00118 007C Svarh = Svarl+1 ; start of vars high byte (Start-of-Variables)
00119 007D Sarryl = $7D ; var mem end low byte (Start-of-Arrays)
00120 007E Sarryh = Sarryl+1 ; var mem end high byte (Start-of-Arrays)
00121 007F Earryl = $7F ; array mem end low byte (End-of-Arrays)
00122 0080 Earryh = Earryl+1 ; array mem end high byte (End-of-Arrays)
00123 0081 Sstorl = $81 ; string storage low byte (String storage (moving down))
00124 0082 Sstorh = Sstorl+1 ; string storage high byte (String storage (moving down))
00125 0083 Sutill = $83 ; string utility ptr low byte
00126 0084 Sutilh = Sutill+1 ; string utility ptr high byte
00127 0085 Ememl = $85 ; end of mem low byte (Limit-of-memory)
00128 0086 Ememh = Ememl+1 ; end of mem high byte (Limit-of-memory)
00129 0087 Clinel = $87 ; current line low byte (Basic line number)
00130 0088 Clineh = Clinel+1 ; current line high byte (Basic line number)
00131 0089 Blinel = $89 ; break line low byte (Previous Basic line number)
00132 008A Blineh = Blinel+1 ; break line high byte (Previous Basic line number)
00133
00134 008B Cpntrl = $8B ; continue pointer low byte
00135 008C Cpntrh = Cpntrl+1 ; continue pointer high byte
00136
00137 008D Dlinel = $8D ; current DATA line low byte
00138 008E Dlineh = Dlinel+1 ; current DATA line high byte
00139
00140 008F Dptrl = $8F ; DATA pointer low byte
00141 0090 Dptrh = Dptrl+1 ; DATA pointer high byte
00142
00143 0091 Rdptrl = $91 ; read pointer low byte
00144 0092 Rdptrh = Rdptrl+1 ; read pointer high byte
00145
00146 0093 Varnm1 = $93 ; current var name 1st byte
00147 0094 Varnm2 = Varnm1+1 ; current var name 2nd byte
00148
00149 0095 Cvaral = $95 ; current var address low byte
00150 0096 Cvarah = Cvaral+1 ; current var address high byte
00151
00152 0097 Frnxtl = $97 ; var pointer for FOR/NEXT low byte
00153 0098 Frnxth = Frnxtl+1 ; var pointer for FOR/NEXT high byte
00154
00155 0097 Tidx1 = Frnxtl ; temp line index
00156
00157 0097 Lvarpl = Frnxtl ; let var pointer low byte
00158 0098 Lvarph = Frnxth ; let var pointer high byte
00159
00160 0099 prstk = $99 ; precedence stacked flag
00161
00162 009B comp_f = $9B ; compare function flag, bits 0,1 and 2 used
00163 ; bit 2 set if >
00164 ; bit 1 set if =
00165 ; bit 0 set if <
00166
00167 009C func_l = $9C ; function pointer low byte
00168 009D func_h = func_l+1 ; function pointer high byte
00169
00170 009C garb_l = func_l ; garbage collection working pointer low byte
00171 009D garb_h = func_h ; garbage collection working pointer high byte
00172
00173 009E des_2l = $9E ; string descriptor_2 pointer low byte
00174 009F des_2h = des_2l+1 ; string descriptor_2 pointer high byte
00175
00176 00A0 g_step = $A0 ; garbage collect step size
00177
00178 00A1 Fnxjmp = $A1 ; jump vector for functions
00179 00A2 Fnxjpl = Fnxjmp+1 ; functions jump vector low byte
00180 00A3 Fnxjph = Fnxjmp+2 ; functions jump vector high byte
00181
00182 00A2 g_indx = Fnxjpl ; garbage collect temp index
00183
00184 00A3 FAC2_r = $A3 ; FAC2 rounding byte
00185
00186 00A4 Adatal = $A4 ; array data pointer low byte
00187 00A5 Adatah = Adatal+1 ; array data pointer high byte
00188
00189 00A4 Nbendl = Adatal ; new block end pointer low byte
00190 00A5 Nbendh = Adatah ; new block end pointer high byte
00191
00192 00A6 Obendl = $A6 ; old block end pointer low byte
00193 00A7 Obendh = Obendl+1 ; old block end pointer high byte
00194
00195 00A8 numexp = $A8 ; string to float number exponent count
00196 00A9 expcnt = $A9 ; string to float exponent count
00197
00198 00A8 numbit = numexp ; bit count for array element calculations
00199
00200 00AA numdpf = $AA ; string to float decimal point flag
00201 00AB expneg = $AB ; string to float eval exponent -ve flag
00202
00203 00AA Astrtl = numdpf ; array start pointer low byte
00204 00AB Astrth = expneg ; array start pointer high byte
00205
00206 00AA Histrl = numdpf ; highest string low byte
00207 00AB Histrh = expneg ; highest string high byte
00208
00209 00AA Baslnl = numdpf ; BASIC search line pointer low byte
00210 00AB Baslnh = expneg ; BASIC search line pointer high byte
00211
00212 00AA Fvar_l = numdpf ; find/found variable pointer low byte
00213 00AB Fvar_h = expneg ; find/found variable pointer high byte
00214
00215 00AA Ostrtl = numdpf ; old block start pointer low byte
00216 00AB Ostrth = expneg ; old block start pointer high byte
00217
00218 00AA Vrschl = numdpf ; variable search pointer low byte
00219 00AB Vrschh = expneg ; variable search pointer high byte
00220
00221 00AC FAC1_e = $AC ; FAC1 exponent
00222 00AD FAC1_1 = FAC1_e+1 ; FAC1 mantissa1
00223 00AE FAC1_2 = FAC1_e+2 ; FAC1 mantissa2
00224 00AF FAC1_3 = FAC1_e+3 ; FAC1 mantissa3
00225 00B0 FAC1_s = FAC1_e+4 ; FAC1 sign (b7)
00226
00227 00AC str_ln = FAC1_e ; string length
00228 00AD str_pl = FAC1_1 ; string pointer low byte
00229 00AE str_ph = FAC1_2 ; string pointer high byte
00230
00231 00AE des_pl = FAC1_2 ; string descriptor pointer low byte
00232 00AF des_ph = FAC1_3 ; string descriptor pointer high byte
00233
00234 00AF mids_l = FAC1_3 ; MID$ string temp length byte
00235
00236 00B1 negnum = $B1 ; string to float eval -ve flag
00237 00B1 numcon = $B1 ; series evaluation constant count
00238
00239 00B2 FAC1_o = $B2 ; FAC1 overflow byte
00240
00241 00B3 FAC2_e = $B3 ; FAC2 exponent
00242 00B4 FAC2_1 = FAC2_e+1 ; FAC2 mantissa1
00243 00B5 FAC2_2 = FAC2_e+2 ; FAC2 mantissa2
00244 00B6 FAC2_3 = FAC2_e+3 ; FAC2 mantissa3
00245 00B7 FAC2_s = FAC2_e+4 ; FAC2 sign (b7)
00246
00247 00B8 FAC_sc = $B8 ; FAC sign comparison, Acc#1 vs #2
00248 00B9 FAC1_r = $B9 ; FAC1 rounding byte
00249
00250 00B8 ssptr_l = FAC_sc ; string start pointer low byte
00251 00B9 ssptr_h = FAC1_r ; string start pointer high byte
00252
00253 00B8 sdescr = FAC_sc ; string descriptor pointer
00254
00255 00BA csidx = $BA ; line crunch save index
00256 00BA Asptl = csidx ; array size/pointer low byte
00257 00BB Aspth = $BB ; array size/pointer high byte
00258
00259 00BA Btmpl = Asptl ; BASIC pointer temp low byte
00260 00BB Btmph = Aspth ; BASIC pointer temp low byte
00261
00262 00BA Cptrl = Asptl ; BASIC pointer temp low byte
00263 00BB Cptrh = Aspth ; BASIC pointer temp low byte
00264
00265 00BA Sendl = Asptl ; BASIC pointer temp low byte
00266 00BB Sendh = Aspth ; BASIC pointer temp low byte
00267
00268 00BC LAB_IGBY = $BC ; get next BASIC byte subroutine
00269
00270 00C2 LAB_GBYT = $C2 ; get current BASIC byte subroutine
00271 00C3 Bpntrl = $C3 ; BASIC execute (get byte) pointer low byte
00272 00C4 Bpntrh = Bpntrl+1 ; BASIC execute (get byte) pointer high byte
00273
00274 ; = $D7 ; end of get BASIC char subroutine
00275
00276 00D8 Rbyte4 = $D8 ; extra PRNG byte
00277 00D9 Rbyte1 = Rbyte4+1 ; most significant PRNG byte
00278 00DA Rbyte2 = Rbyte4+2 ; middle PRNG byte
00279 00DB Rbyte3 = Rbyte4+3 ; least significant PRNG byte
00280
00281 00DC NmiBase = $DC ; NMI handler enabled/setup/triggered flags
00282 ; bit function
00283 ; === ========
00284 ; 7 interrupt setup
00285 ; 6 interrupt enabled
00286 ; 5 interrupt happened
00287 ; = $DD ; NMI handler addr low byte
00288 ; = $DE ; NMI handler addr high byte
00289 00DF IrqBase = $DF ; IRQ handler enabled/setup/triggered flags
00290 ; = $E0 ; IRQ handler addr low byte
00291 ; = $E1 ; IRQ handler addr high byte
00292
00293 00E2 irq_a_reg = $E2 ; save A during IRQ
00294 ; = $E3 ; unused
00295 ; = $E4 ; unused
00296 ; = $E5 ; unused
00297 ; = $E6 ; unused
00298 ; = $E7 ; unused
00299 ; = $E8 ; unused
00300 ; = $E9 ; unused
00301 ; = $EA ; unused
00302 ; = $EB ; unused
00303 ; = $EC ; unused
00304 ; = $ED ; unused
00305 ; = $EE ; unused
00306
00307 00EF Decss = $EF ; number to decimal string start
00308 00F0 Decssp1 = Decss+1 ; number to decimal string start
00309
00310 ; = $FF ; decimal string end
6502 sources on GitHub: https://github.com/Klaus2m5
Re: Page 0 available locations
Thanks Klaus.
Isn't some code loaded in to page 0 somewhere?
If not, then that's more free than I expected - good stuff!
Isn't some code loaded in to page 0 somewhere?
If not, then that's more free than I expected - good stuff!
Bill
Re: Page 0 available locations
Yes, code is loaded at $BC-$D7, the get BASIC char subroutine. I think the big gap $14-$5A was originally reserved for the input buffer. But that was moved away from page zero in EhBASIC.
6502 sources on GitHub: https://github.com/Klaus2m5