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Creating ASM65.COM ------------------ Thσ ASM6╡ assemble≥ ha≤ beeε buil⌠ a≤ aε overla∙ t∩ Digita∞ ì Research'≤ AS═ assemble≥ fo≥ 808░ serie≤ processors« T∩ protec⌠ ì you≥ CP/═ licencσ froφ Digita∞ Research¼ ASM6╡ i≤ supplieΣ onl∙ ì iε .HE╪ form¼ anΣ mus⌠ bσ mergeΣ witΦ aε existinτ cop∙ oµ ASM.CO═ ì usinτ DD╘ o≥ ß simila≥ 8080/Z8░ debugger« Usinτ DDT¼ thσ ì conversatioε t∩ creatσ ASM65.CO═ i≤ a≤ follows: A>ddt asm.com DDT VERS 2.2 NEXT PC 2100 0100 -iasm65.hex -r NEXT PC 2300 0100 -^C A>save 34 asm65.com èBackground ---------- ASM6╡ i≤ ß 650▓ cross-assemble≥ fo≥ CP/═ system≤ -- iε othe≥ ì word≤ i⌠ use≤ 650▓ assembl∙ languagσ t∩ creatσ program≤ fo≥ 6502-ì baseΣ systems¼ bu⌠ thσ assemble≥ itselµ run≤ oε CP/═ systems¼ ì allowinτ thσ usσ oµ better-qualit∙ editor≤ sucΦ a≤ WordSta≥ anΣ ì Spellbinde≥ t∩ creatσ prograφ source« I⌠ i≤ ß ful∞ conditiona∞ ì bu⌠ non-macr∩ assemble≥ supportinτ al∞ 650▓ opcode≤ anΣ ì addressinτ mode≤ (includinτ thσ extension≤ supporteΣ oε thσ GT┼ ì 65C0▓ processor⌐ witΦ ß gooΣ rangσ oµ pseudo-operations« I⌠ doe≤ ì NOT conver⌠ 8080/Z8░ assembl∙ languagσ program≤ t∩ 650▓ ì equivalents. Wσ assumσ tha⌠ yo⌡ arσ familia≥ witΦ assembl∙ languagσ ì programminτ -- iµ not¼ wσ woulΣ advisσ readinτ '650▓ Assembl∙ ì Languagσ Programmingº (Leventhal¼ Osborne/McGraw-Hill⌐ o≥ aε ì equivalen⌠ iε conjunctioε witΦ thesσ notes« Wσ als∩ assumσ tha⌠ ì yo⌡ havσ ß cop∙ oµ thσ Digita∞ ResearcΦ AS═ manua∞ t∩ hand¼ a≤ wσ ì wil∞ refe≥ t∩ i⌠ fo≥ description≤ oµ pseudo-ops¼ erro≥ message≤ ì anΣ thσ like. Iε general¼ thσ assembl∙ languagσ useΣ iε ASM6╡ follow≤ standarΣ ì MO╙ Technolog∙ syntax¼ bu⌠ therσ arσ somσ deviation≤ froφ thσ ì standarΣ (enforceΣ b∙ usinτ a≤ corσ aε assemble≥ designeΣ fo≥ thσ ì 8080/Z8░ processo≥ family⌐ whicΦ ma∙ affec⌠ portabilit∙ oµ ì program≤ t∩ standarΣ 650▓ assemblers« Thσ maiε difference≤ arσ iε ì thσ specificatioε oµ numeriπ value≤ (in suffixe≤ rathe≥ thaε ì prefixe≤ arσ useΣ t∩ distinguisΦ numbe≥ bases)╗ iε pseudo-o≡ ì names¼ whicΦ arσ standarΣ AS═ syntax; anΣ iε thσ descriptioε oµ ì indirec⌠ addressinτ modes« Bracket≤ arσ useΣ t∩ enclosσ ì arithmetiπ expression≤ iε AS═ syntax¼ witΦ thσ resul⌠ tha⌠ ì indirec⌠ addressinτ mode≤ canno⌠ bσ specifieΣ b∙ enclosinτ thσ ì operanΣ iε bracket≤ a≤ pe≥ MO╙ Technolog∙ synta° -- onσ non-ì standarΣ opcodσ (JMPI⌐ anΣ slightl∙ differen⌠ registe≥ mnemonic≤ ì (IX¼ I┘ anΣ I⌐ arσ useΣ instead. Preparing source files ---------------------- Prograφ creatioε witΦ ASM6╡ i≤ ß three-stagσ process: editinτ thσ ì sourcσ filσ witΦ ß suitablσ edito≥ o≥ word-processor╗ usinτ ASM6╡ ì t∩ creatσ ß he° file╗ anΣ creatinτ ß binar∙ filσ froφ thσ he° ì filσ witΦ LOA─ o≥ CODE¼ o≥ sendinτ i⌠ direc⌠ t∩ thσ externa∞ ì 6502-baseΣ system« Thi≤ par⌠ oµ thσ note≤ i≤ concerneΣ onl∙ witΦ ì the first stage, that of source-file creation. Program≤ caε bσ createΣ usinτ an∙ suitablσ CP/═ edito≥ o≥ word-ì processo≥ (wσ mainl∙ usσ WordStar¼ whicΦ allow≤ u≤ sourcσ file≤ ì oµ an∙ length)« Filename≤ MUST usσ thσ extensioε .A6╡ (e.g« ì PROGRAM.A65)¼ otherwisσ ASM6╡ wil∞ no⌠ finΣ thσ filσ -- thσ erro≥ ì message 'No source file present' will be printed in this case. As usual, assembly language statements take the form of: <label:> opcode <operand> <;comment> -- eacΦ linσ ends¼ oµ course¼ witΦ carriage-returε o≥ thσ CR/L╞ ì combination.è Linσ number≤ shoulΣ no⌠ bσ useΣ (thougΦ seσ thσ AS═ manua∞ fo≥ ì more detail if you REALLY want to use line numbers). Labels ------ Label≤ ma∙ bσ oµ an∙ length¼ althougΦ onl∙ 1╢ character≤ arσ ì significant« The∙ ma∙ bσ writteε a≤ eithe≥ uppe≥ o≥ lowe≥ casσ ì letter≤ (lower-casσ letter≤ arσ converteΣ t∩ cap≤ automaticall∙ ì durinτ assembly⌐ anΣ numeral≤ (althougΦ thσ firs⌠ characte≥ oµ ß ì labe∞ mus⌠ bσ ß letter« Thσ ':º i≤ optional« Wherσ ß labe∞ refer≤ ì t∩ aε assignmen⌠ (EQ╒ o≥ SET⌐ i⌠ mus⌠ bσ oε thσ samσ line╗ ì otherwise¼ wherσ i⌠ refer≤ t∩ codσ (opcode≤ o≥ code-creatinτ ì pseudo-op≤ sucΦ a≤ DB⌐ i⌠ doe≤ no⌠ neeΣ t∩ bσ oε thσ samσ line¼ ì s∩ tha⌠ multiplσ label≤ ma∙ refe≥ t∩ thσ samσ codσ location« Seσ ì the ASM manual for more detail. Multiple expressions -------------------- Opcode≤ anΣ operand≤ arσ describeΣ iε detai∞ below¼ anΣ wil∞ no⌠ ì bσ discusseΣ here« Note¼ however¼ tha⌠ severa∞ opcode/operanΣ ì expression≤ ma∙ bσ placeΣ oε thσ samσ line if separated by '!': PHA ! TXA ! PHA ! TYA ! PHA ;save registers -- onσ side-effec⌠ i≤ tha⌠ '!º ma∙ no⌠ bσ useΣ iε comments¼ ì otherwisσ ASM6╡ interpret≤ thσ followinτ tex⌠ a≤ sourcσ ì statements, with unpredictable results. Comments -------- ┴ commen⌠ i≤ precedeΣ b∙ ';'¼ anΣ run≤ t∩ thσ enΣ oµ thσ linσ ì (witΦ thσ exceptioε oµ '!º a≤ describeΣ above)« Therσ i≤ n∩ ì provisioε fo≥ multiple-linσ comment≤ -- eacΦ linσ oµ commen⌠ mus⌠ ì bσ precedeΣ b∙ ';º -- althougΦ comment≤ ma∙ star⌠ a⌠ an∙ positioε ì in the line. EacΦ par⌠ oµ thσ statemen⌠ mus⌠ bσ separateΣ b∙ a⌠ leas⌠ onσ ì spacσ o≥ tab« Apar⌠ froφ this¼ space≤ anΣ tab≤ arσ no⌠ ì significant¼ anΣ ma∙ bσ useΣ iε an∙ wa∙ t∩ increasσ thσ ì readability of the file. Opcodes ------- ASM6╡ support≤ al∞ standarΣ MO╙ Technolog∙ anΣ GT┼ (65C02⌐ opcodσ ì mnemonics¼ witΦ onσ exception║ JMP╔ i≤ useΣ iε placσ oµ JM╨ (..⌐ ì fo≥ jump-indirect« WitΦ tha⌠ exception¼ al∞ opcodσ mnemonic≤ arσ ì three-letter╗ thσ four-lette≥ mnemonic≤ ASLA¼ ROLA¼ LSRA¼ ROR┴ ì (anΣ INCA¼ DEC┴ -- 65C0▓ only⌐ ma∙ als∩ bσ useΣ t∩ describeΣ ì accumulator operations. Thσ opcodσ lis⌠ belo≈ show≤ al∞ oµ thσ opcode≤ availablσ witΦ ì ASM65¼ includinτ 65C0▓ extensions« Thσ addressinτ mode≤ availablσ ì fo≥ eacΦ instructioε arσ showε iε brackets¼ witΦ mode≤ availablσ ì onl∙ oε thσ 65C0▓ indicateΣ b∙ aε asterisk« Thσ mode≤ arσ ì repesented by: (none) implicit operation A accumulator only # immediate (8-bit value)è Z zero page (8-bit address) Abs absolute (16-bit address) Rel relative (8-bit signed branch) Z,X zero page + X register Z,Y zero-page + Y register Abs,X absolute + X register Abs,Y absolute + Y register IX indirect from (zpage + X register) IY indirect from zpage, + Y register I indirec⌠ froφ zpagσ (samσ a≤ I┘ witΦ Y=0⌐ (65C0▓ ì áááááááááááááááonly) Implicit operations ------------------- PHA, PLA push/pull accumulator PHP, PLP push/pull processor status flags PHX, PLX push/pull X register (65C02 only) PHY, PLY push/pull Y register (65C02 only) TSX move stack pointer to X register TXS set stack pointer from X register TAX, TAY load X, Y register from A TXA, TYA load A from X, Y register SEC, SED, SEI set carry, decimal, interrupt flags CLC, CLD clear carry, decimal flags CLI, CLV clear interrupt, overflow flags RTS, RTI return from subroutine, interrupt BRK break (software interrupt) NOP no-operation Call, Jump and Branch --------------------- JSR call subroutine (Abs) JMP jump to new location (Abs) JMPI jum≡ indirec⌠ viß specifieΣ locatioε (Abs╗ ì ááááááááááááááááááááAbs,X*) BPL, BMI branch if sign clear/set (Rel) BNE, BEQ branch if zero flag clear/set (Rel) BCC, BCS branch if carry clear/set (Rel) BVC, BVS branch if overflow flag clear/set (Rel) BRA unconditional branch (Rel*) Test/Set/Reset memory --------------------- BIT test memory bits (Z; Abs; Z,X*; Abs,X*; #*) TRB tes⌠ anΣ rese⌠ memor∙ agains⌠ accumulato≥ ì áááááááááááááááááááá(Z*╗ Abs*) TSB tes⌠ anΣ se⌠ memor∙ agains⌠ accumulato≥ (Z*╗ ì ááááááááááááááááááááAbs*) Rotate and Shift ---------------- ASL shift left (Z; Abs; Z,X; Abs,X; A) ASLA shift A left (same as ASL A) LSR shift right (Z; Abs; Z,X; Abs,X; A) LSRA shift A left (same as LSR A) ROL rotatσ lef⌠ -- 9-bi⌠ rotatσ througΦ carr∙ (Z╗ ì ááááááááááááááááááááAbs╗ Z,X╗ Abs,X╗ A) ROLA rotate A left (same as ROL A) ROR rotatσ righ⌠ -- 9-bi⌠ rotatσ througΦ carr∙ ìèáááááááááááááááááááá(Z╗ Abs╗ Z,X╗ Abs,X╗ A) RORA rotate A right (same as ROR A) Decrement and Increment ----------------------- DEC decrement (Z; Abs; Z,X; Abs,X; A*) DECA decrement A (same as DEC A*) INC increment (Z; Abs; Z,X; Abs,X; A*) INCA increment A (same as INC A*) DEX, INX decrement/increment X DEY, INY decrement/increment Y Accumulator operations ---------------------- ORA inclusivσ O╥ witΦ accumulato≥ (#╗ Z╗ Abs╗ ì ááááááááááááááááááááZ,X╗ Abs,X╗ Abs,Y╗ IX╗ IY╗ I*) AND binar∙ AN─ witΦ accumulato≥ (#╗ Z╗ Abs╗ Z,X╗ ì ááááááááááááááááááááAbs,X╗ Abs,Y╗ IX╗ IY╗ I*) EOR exclusivσ O╥ witΦ accumulato≥ (#╗ Z╗ Abs╗ ì ááááááááááááááááááááZ,X╗ Abs,X╗ Abs,Y╗ IX╗ IY╗ I*) ADC adΣ witΦ carr∙ t∩ accumulato≥ (#╗ Z╗ Abs╗ ì ááááááááááááááááááááZ,X╗ Abs,X╗ Abs,Y╗ IX╗ IY╗ I*) SBC subtrac⌠ witΦ borro≈ froφ accumulato≥ (#╗ Z╗ ì ááááááááááááááááááááAbs╗ Z,X╗ Abs,X╗ Abs,Y╗ IX╗ IY╗ I*) Load and Store -------------- LDA loaΣ ┴ registe≥ (#╗ Z╗ Abs╗ Z,X╗ Abs,X╗ ì ááááááááááááááááááááAbs,Y╗ IX╗ IY╗ I*) STA storσ ┴ registe≥ (Z╗ Abs╗ Z,X╗ Abs,X╗ Abs,Y╗ ì ááááááááááááááááááááIX╗ IY╗ I*) LDX load X register (#; Z; Abs; Z,Y; Abs,Y) STX store X register (Z; Abs; Z,Y) LDY load Y register (#; Z; Abs; Z,X; Abs,X) STY store Y register (Z; Abs; Z,X) Compare registers ----------------- CMP comparσ accumulato≥ (#╗ Z╗ Abs╗ Z,X╗ Abs,X╗ ì ááááááááááááááááááááAbs,Y╗ IX╗ IY╗ I*) CPX compare X (#; Z; Abs) CPY compare Y (#; Z; Abs) Addressing modes ---------------- (none) implicit operation A accumulator only áááááááááááááááUseΣ wherσ accumulato≥ i≤ thσ operand¼ e.g« AS╠ A« ì áááááááááááááááAl∞ ┴ addressinτ option≤ havσ ß 4-lette≥ matchinτ ì áááááááááááááááopcode -- i.e. ASLA and ASL A are identical. # immediate (8-bit value) áááááááááááááááNex⌠ bytσ i≤ thσ operand« Example≤ arσ LD┴ #20¼ ì áááááááááááááááLD╪ #20h¼ CP╪ #'i'« Aε erro≥ i≤ generateΣ iµ thσ ì áááááááááááááááoperand evaluates to greater than 0FFh. Z zero page (8-bit address) áááááááááááááááNex⌠ bytσ i≤ thσ low-orde≥ addres≤ oµ thσ operand« ì áááááááááááááááSelecteΣ automaticall∙ iµ thσ operanΣ evaluate≤ t∩ ì áááááááááááááááles≤ thaε 100h« Example≤ arσ LD┴ 20¼ ST╪ 20h¼ anΣ ì áááááááááááááááORA <address> where <address> is less than 100h. áááááááááááááááAl∞ zero-pagσ addresse≤ mus⌠ bσ knowε oε thσ firs⌠ ìèááááááááááááááápass¼ withou⌠ forwarΣ references¼ otherwisσ phasσ ì áááááááááááááááerror≤ (seσ AS═ manual⌐ ma∙ occu≥ durinτ thσ ì ááááááááááááááásecond pass of the assembler. Abs absolute (16-bit address) áááááááááááááááNex⌠ bytσ i≤ thσ low-orde≥ addres≤ oµ thσ operand╗ ì áááááááááááááááfollowinτ bytσ i≤ thσ high-orde≥ address« SelecteΣ ì áááááááááááááááautomaticall∙ iµ thσ operanΣ evaluate≤ t∩ greate≥ ì áááááááááááááááthaε 0FFh¼ o≥ iµ zero-pagσ modσ i≤ no⌠ available« ì áááááááááááááááExample≤ arσ LD┴ 2000¼ ST╪ 200h¼ anΣ OR┴ <address> ì áááááááááááááááwhere <address> is greater than 0FFh. Rel relative (8-bit signed branch) áááááááááááááááNex⌠ bytσ i≤ thσ offse⌠ t∩ ß labe∞ relativσ t∩ thσ ì ááááááááááááááástar⌠ oµ thσ NEXT instructioε (i.e« tw∩ byte≤ ì áááááááááááááááafte≥ thσ locatioε oµ thσ brancΦ test)¼ givinτ aε ì áááááááááááááááeffectivσ rangσ oµ -12╢ t∩ +12╣ froφ thσ locatioε ì áááááááááááááááoµ thσ brancΦ instruction« Iµ thσ operanΣ ì áááááááááááááááevaluate≤ outsidσ thi≤ range¼ aε erro≥ wil∞ bσ ì ááááááááááááááágenerated« Example≤ arσ BR┴ label¼ BN┼ $-│ ('$º i≤ ì áááááááááááááááthe reserved name of the position counter). Z,X zero page + X register áááááááááááááááA≤ fo≥ ┌ above¼ excep⌠ thσ content≤ oµ thσ ╪ ì áááááááááááááááregiste≥ arσ addeΣ t∩ givσ aε offse⌠ withiε thσ ì ááááááááááááááázero-page« Addresse≤ 'wra≡ roundº WITHIN zero-ì ááááááááááááááápage. Example: AND address,X Z,Y zero-page + Y register áááááááááááááááA≤ fo≥ Z,╪ above¼ excep⌠ tha⌠ thσ ┘ registe≥ i≤ ì áááááááááááááááused. Example: STX 20h,Y Abs,X absolute + X register áááááááááááááááA≤ fo≥ Ab≤ above¼ excep⌠ tha⌠ thσ content≤ oµ thσ ì ááááááááááááááá╪ registe≥ arσ addeΣ t∩ givσ aε offse⌠ froφ thσ ì áááááááááááááááfollowinτ two-bytσ address« Addresse≤ d∩ no⌠ 'wra≡ ì ááááááááááááááároundº withiε thσ curren⌠ pagσ -- wherσ thσ suφ oµ ì áááááááááááááááthσ low-orde≥ addres≤ anΣ thσ ╪ registe≥ content≤ ì áááááááááááááááexceed≤ 0FFh¼ thσ high-orde≥ addres≤ i≤ ì áááááááááááááááincremented. Example: SBC 2000h,X Abs,Y absolute + Y register áááááááááááááááA≤ fo≥ Abs,╪ above¼ excep⌠ tha⌠ thσ ┘ registe≥ i≤ ì áááááááááááááááused« Example║ AD├ address,┘ (wherσ addres≤ i≤ ì ááááááááááááááágreater than 0FFh). IX indirect from (zpage + X register) áááááááááááááááThσ followinτ bytσ i≤ thσ lo≈ orde≥ addres≤ withiε ì ááááááááááááááázero-pagσ t∩ whicΦ thσ ╪ registe≥ i≤ addeΣ ì ááááááááááááááá('wrappinτ roundº iµ necessary)« Thσ effectivσ ì áááááááááááááááoperanΣ i≤ thσ addres≤ pointeΣ t∩ by thσ content≤ ì áááááááááááááááoµ thσ effectivσ addres≤ generated« Iµ thσ basσ ì áááááááááááááááaddres≤ doe≤ no⌠ evaluatσ t∩ aε 8-bi⌠ addres≤ ì ááááááááááááááá(i.e« thσ high-orde≥ bytσ i≤ greate≥ thaε zero⌐ ì áááááááááááááááan error is generated. Example: LDA base,IX IY indirect from zpage, + Y register áááááááááááááááSimila≥ t∩ IX¼ excep⌠ tha⌠ thσ content≤ oµ thσ ┘ ì áááááááááááááááregiste≥ arσ addeΣ AFTER thσ indirectioε -- thσ ì ááááááááááááááácontent≤ oµ thσ ┘ registe≥ arσ addeΣ t∩ thσ ì ááááááááááááááácontent≤ oµ thσ tw∩ byte≤ a⌠ 'addressº (withiε ì ááááááááááááááázero-page⌐ t∩ creatσ thσ effectivσ address« Iµ thσ ì ááááááááááááááábasσ addres≤ doe≤ no⌠ evaluatσ t∩ aε 8-bi⌠ addres≤ ìèáááááááááááááááan error is generated. Example: CMP 20h,IY I indirec⌠ froφ zpagσ áááááááááááááááThσ effectivσ addres≤ i≤ thσ content≤ oµ thσ tw∩ ì ááááááááááááááábyte≤ startinτ a⌠ thσ followinτ addres≤ iε zero-ì ááááááááááááááápage« Thi≤ i≤ identica∞ t∩ I┘ iε case≤ wherσ thσ ┘ ì áááááááááááááááregister is zero. Example: AND flag,I Tw∩ othe≥ addressinτ mode≤ arσ available¼ bu⌠ onl∙ witΦ thσ JM╨ ì instruction║ absolutσ indirect¼ anΣ absolutσ indexeΣ indirect« ì Thesσ arσ availablσ a≤ JMP╔ Ab≤ anΣ JMP╔ Abs,╪ respectively╗ thσ ì JMP instruction has only the Abs addressing mode. Numeric values -------------- (Note║ Thi≤ i≤ NOT thσ samσ a≤ MO╙ Technolog∙ syntax)« Fou≥ ì numbe≥ base≤ arσ recognised║ binary¼ octal¼ decima∞ anΣ ì hexadecimal« Thesσ arσ representeΣ b∙ thσ followinτ suffixes: B binary -- 011011b O or Q octal -- 377q D decimal (defaults to decimal) -- 100, 100d H hexadecimal -- 20h, 0FFh Al∞ numeriπ value≤ MUST star⌠ witΦ ß numbe≥ -- he° value≤ abovσ ì 9Fh must be prefixed by 0. Numeriπ value≤ arσ treateΣ a≤ 16-bi⌠ unsigneΣ numbers╗ thσ ì addressinτ modσ useΣ check≤ tha⌠ thσ numbe≥ i≤ withiε it≤ ì required range. Arithmetic expressions ---------------------- Operand≤ ma∙ includσ arithmetiπ expression≤ oµ considerablσ ì complexity« Thσ followinτ i≤ ß lis⌠ oµ thσ function≤ anΣ ì operator≤ tha⌠ ma∙ bσ useΣ withiε arithmetiπ expressions« * times + plus - minus / divide MOD remainder from divide & binary AND (note -- not 'AND', which is a 6502 opcode) OR binary inclusive-OR XOR binary exclusive-OR NOT binary negate SHL binary shift-left SHR binary shift-right Al∞ arithmetiπ operation≤ ac⌠ oε thσ curren⌠ valuσ a≤ ß 16-bi⌠ ì unsigneΣ number« Bracket≤ -- ¿ ⌐ -- enclosσ thesσ expression≤ anΣ ì ma∙ bσ nesteΣ u≡ t∩ si° deep╗ bracket≤ caε als∩ bσ useΣ t∩ forcσ ì thσ orde≥ oµ evaluatioε oµ aε expression« Seσ thσ AS═ manua∞ fo≥ ì morσ details. Literal expressions ------------------- Tex⌠ (o≥ individua∞ letters⌐ ma∙ bσ includeΣ iε operand≤ b∙ ì enclosinτ it in single quotes, e.g.:è CMP #'T' db 'text' Wherσ single-quote≤ character≤ arσ t∩ bσ included¼ the∙ mus⌠ bσ ì repeated: db 'it''s a little confusing' CMP #'''' ;is A single-quote? For more details, see the ASM manual. Pseudo-operations ----------------- Pseudo-op≤ fal∞ int∩ fivσ groups║ defininτ o≥ reservinτ space¼ ì defininτ constant≤ o≥ variables¼ defininτ thσ locatioε counter¼ ì delimitinτ area≤ fo≥ conditiona∞ assembly¼ anΣ (a≤ ye⌠ ì unimplemented⌐ expansioε instructions« Onl∙ ß brieµ summar∙ i≤ ì given here: for more detail refer to the ASM manual. Defining space -------------- DB definσ bytσ (equivalen⌠ oµ .BYT┼ iε MO╙ Technolog∙ syntax)« ì áááááReservσ bytσ orienteΣ spacσ anΣ it≤ contents¼ sucΦ a≤ ì áááááconstants, variables or embedded text. áááááExamples: ááááá db 0,0,0,0,22,105,0 ááááá db 'text',0 áááááIµ an∙ valuσ evaluate≤ t∩ greate≥ thaε 0FFh¼ aε erro≥ wil∞ ì ááááábe generated. DWááádefinσ worΣ (equivalen⌠ oµ .WOR─ iε MO╙ Technolog∙ syntax)« ì áááááReservσ word-orienteΣ spacσ anΣ it≤ contents¼ witΦ thσ ì ááááácontent≤ storeΣ iε lo-hΘ order╗ typicall∙ useΣ t∩ definσ ì áááááaddress tables. áááááExample: ááááá dw word1,word2,0,0FFFFh DSááádefinσ reserveΣ areß witΦ undefineΣ contents╗ typicall∙ useΣ ì áááááto define scratchpad areas. áááááExample: ááááá ds 255 Defining constants or variables ------------------------------- EQU assigε ß constan⌠ valuσ t∩ 'labelº (equivalen⌠ oµ '=º iε MO╙ ì áááááTechnolog∙ syntax)« Thσ labe∞ mus⌠ bσ iε thσ samσ line« ì áááááValue≤ arσ considereΣ t∩ bσ 16-bi⌠ unsigneΣ numbers¼ anΣ ma∙ ì ááááábσ addresses¼ characte≥ constants¼ o≥ 16- o≥ 8-bi⌠ value≤ oµ ì áááááan∙ kind« Iµ ß constan⌠ i≤ defineΣ morσ thaε oncσ usinτ EQU¼ ì áááááaε erro≥ wil∞ bσ generated. Example: ááááá eof EQU 1ah SETááassigε ß variablσ valuσ t∩ 'label'« Thσ samσ a≤ EQU¼ excep⌠ ì ááááátha⌠ n∩ erro≥ wil∞ bσ generateΣ iµ i⌠ i≤ redefined« ì áááááTypicall∙ useΣ t∩ specif∙ variable≤ t∩ contro∞ o≥ fo≥ usσ iε ì áááááconditional assembly. áááááExample: ááááá flag SET 1 èDefining the location counter ----------------------------- ORGááDefine≤ thσ curren⌠ locatioε counte≥ froφ whicΦ addresse≤ ì áááááwil∞ bσ calculateΣ (samσ a≤ '*=º iε MO╙ Technolog∙ syntax)« ì áááááMa∙ bσ defineΣ o≥ redefineΣ a⌠ an∙ timσ -- shoulΣ onl∙ bσ ì ááááádefineΣ t∩ ß highe≥ address¼ a≤ redefinition≤ t∩ lowe≥ ì áááááaddresse≤ thaε thσ curren⌠ addres≤ ma∙ causσ problem≤ a⌠ ì áááááfina∞ assembly. áááááExample: ááááá org 0f000h ENDááDefine≤ thσ enΣ oµ thσ prograφ a≤ fa≥ a≤ assembl∙ i≤ ì áááááconcerned. Optional. Conditional assembly -------------------- IFáááStar⌠ oµ sectioε whicΦ wil∞ bσ assembleΣ onl∙ iµ thσ ì áááááfollowinτ conditioε i≤ truσ (non-zero)« Onl∙ onσ leve∞ oµ ì áááááconditional assembly is available. áááááExample: ááááá testversion equ 1 ááááá IF testversion ááááá jsr printstatus ááááá ENDIF ááááá IF not testversion ááááá jsr clrstatus ááááá ENDIF ááááá jmp mainloop ENDIF áááááEnd≤ ß sectioε oµ conditiona∞ assembly« ┴ missinτ o≥ ì áááááunmatched ENDIF will cause an error to be generated. Unimplemented instructions -------------------------- Thσ followinτ instruction≤ arσ treateΣ a≤ reserveΣ words¼ bu⌠ ì arσ no⌠ ye⌠ implementeΣ -- thei≥ usσ wil∞ causσ aε erro≥ t∩ bσ ì generated: MACRO ENDM TITLE Error messages -------------- Assembl∙ erro≥ message≤ arσ rudimentary¼ consistinτ oµ ß singlσ ì lette≥ iε thσ firs⌠ columε oµ thσ listinτ (.PRN⌐ filσ anΣ thσ ì displa∙ oε thσ consolσ oµ thσ relevan⌠ line« Wherσ severa∞ error≤ ì occu≥ withiε thσ samσ line¼ onl∙ thσ lette≥ oµ thσ firs⌠ erro≥ ì wil∞ bσ shown« Iε general¼ thσ causσ oµ aε erro≥ wil∞ bσ a≤ ì describeΣ iε thσ lis⌠ iε thσ AS═ manual╗ aε exceptioε i≤ tha⌠ al∞ ì illega∞ addressinτ mode≤ arσ treateΣ a≤ 'Rº (register⌐ errors¼ ì fo≥ whicΦ threσ NOP≤ ('EAEAEA'⌐ wil∞ bσ generateΣ a≤ code« A≤ witΦ ASM¼ assembl∙ continue≤ afte≥ al∞ errors¼ sometime≤ ì causinτ othe≥ error≤ late≥ durinτ assembl∙ a≤ ß 'knock-onº ì effect. èUsing ASM65 ----------- Wσ assumσ tha⌠ yo⌡ havσ createΣ you≥ prograφ oε ß sourcσ filσ ì calleΣ 'filename.A65'« (Notσ tha⌠ thσ filσ mus⌠ usσ thσ extensioε ì '.A65')« ASM6╡ caε creatσ u≡ t∩ tw∩ additiona∞ file≤ froφ thσ ì sourcσ file║ ß '.HEXº file¼ containinτ machinσ codσ iε Inte∞ he° ì format¼ and/o≥ ß '.PRNº listinτ file╗ i⌠ caε als∩ lis⌠ t∩ thσ ì console« Iε al∞ case≤ sourcσ line≤ witΦ error≤ wil∞ bσ listeΣ t∩ ì thσ screeε and¼ iµ thσ printe≥ i≤ enabled¼ t∩ thσ printe≥ a≤ ì well. Typical examples of assemblies are: B>a:asm65 filename whicΦ assume≤ ß sourcσ filσ filename.A6╡ oε thσ B║ drive¼ anΣ ì creates files filename.HEX and filename.PRN on the same drive. B>a:asm65 filename.bbz which does the same, except that no .PRN file will be created. B>a:asm65 filename.bzx whicΦ read≤ thσ sourcσ filσ oε B:¼ doe≤ no⌠ creatσ ß .HE╪ file¼ ì anΣ send≤ thσ listinτ onl∙ t∩ thσ screeε withou⌠ creatinτ ß .PR╬ ì file. Notσ tha⌠ ß .PR╬ filσ ma∙ wel∞ bσ twicσ thσ sizσ oµ you≥ origina∞ ì sourcσ file║ makσ surσ tha⌠ yo⌡ havσ enougΦ disδ spacσ beforσ ì allowing the assembler to create it! Fo≥ ful∞ detail≤ oε thσ actua∞ assembl∙ proces≤ anΣ it≤ erro≥ ì messages, refer to the ASM manual. Creating executable code ------------------------ ASM6╡ doe≤ no⌠ b∙ itselµ creatσ executablσ codσ -- i⌠ create≤ ß ì '.HEXº filσ containinτ it≤ machinσ codσ a≤ loaΣ address¼ he° ì value≤ anΣ checksuφ iε thσ Inte∞ he° format« Thi≤ mus⌠ bσ ì converted to executable code by a separate loader. Digita∞ Research'≤ LOA─ prograφ doe≤ thi≤ fo≥ 8080/Z8░ programs¼ ì anΣ wil∞ als∩ bσ suitablσ fo≥ non-ROMablσ 650▓ code« Thσ catcΦ ì witΦ LOA─ i≤ tha⌠ i⌠ alway≤ create≤ ß filσ assuminτ ß loaΣ ì addres≤ oµ 100h¼ wherea≤ ROMablσ 650▓ codσ wil∞ tenΣ t∩ residσ ì mucΦ highe≥ iε memory╗ LOA─ thereforσ tend≤ t∩ creatσ aε oversizσ ì filσ consistinτ mainl∙ oµ garbage¼ witΦ thσ actua∞ codσ u≡ a⌠ thσ top« ì Thσ solutioε iε thesσ case≤ i≤ t∩ pas≤ thσ he° filσ t∩ aε externa∞ 650▓ ì systeφ fo≥ processinτ it¼ o≥ usσ thσ modifieΣ loader¼ CODE.CO═ (oε ì thi≤ disk)¼ whicΦ automaticall∙ generate≤ aε offse⌠ t∩ storσ ROMablσ ì codσ iε thσ minimuφ sizσ file« PROMLOA─ o≥ somσ othe≥ file-reade≥ caε ì theε transfe≥ thσ codσ t∩ aε externa∞ systeφ o≥ PRO═ programmer.