P* * El Cheapo Assembler * * Utility routines -- init, memory management * DSK '@0:init' REL ASSEMBLE EXT EDITOR EXT RESTORE EXT TEXTEND EXT CODEEND EXT DORG EXT BLSTART EXT BLEND EXT BLDEST EXT BLMOVE EXT STROUT EXT XLEN = $FB ;Number of bytes to swap DO 0 JMP INIT JMP ASSEMBLE JMP EDITOR FIN INIT DFB $A9 ;LDA #SWAPBANK SWAPBANK ENT DFB $01 ;LDA #$01 STA SWAP1 STA SWAP2 LDA #$4C ;JMP -- use SYS 822 to re-enter STA $0336 LDA #REST STA $0338 LDA #$0D STA $0800 ;Text starts at $0800 LDA #00 STA $0801 INIT2 LDA #$36 ;No BASIC STA $01 STA CODEFLAG ;No code present JMP EDITOR * * Current scheme: * $0334-$0338 Vectors * $0800-$xxxx Source code * $8xxx-$9xxx JamaicaMon * $9xxx-$BFFF El Cheapo * $010800-$01xxxx Compiled code * Also storage for source code * MONITOR ENT JSR FIXMEM JMP ($0334) ;Off into the monitor BASIC ENT JSR FIXMEM JSR STROUT DFB 147 TXT 'sys 822 to re-enter',0d DFB 17,17 TXT 'new' DFB 145,145,00 LDA #$37 STA $01 LDA #$00 STA $0800 JMP $A474 REST ;Re-enter code JSR SWAP SEC HEX FB LDA #$36 STA $01 STA CODEFLAG JMP RESTORE FIXMEM LDA CODEFLAG BEQ :TEXT LDA TEXTEND ;Swap code and text CMP CODEEND LDA TEXTEND+1 ;Figure out highest address SBC CODEEND+1 ;that needs swapping BCS :TEXT LDA CODEEND+1 DFB $2C :TEXT LDA TEXTEND+1 SEC SBC #$07 ;Both start at $0800 STA XLEN+1 ;-7 to move to last page LDA #00 STA XLEN JSR SWAP HEX C230 ;REP #$30 -- all 16-bits LDA DORG ;Finally, move assembled code STA BLDEST ;to proper location LDA #$00 DFB 08 ;LDA #$0800 STA BLSTART LDA CODEEND STA BLEND SEC HEX FB ;XCE JMP BLMOVE ;...and hope it doesn't hit us! * Swap banks 0 and 1 SWAP CLC HEX FB ;XCE HEX C230 ;REP #$30 HEX E220 ;SEP #$20 LDX #00 DFB 00 ;LDX #$0000 SLOOP LDA $0800,X PHA HEX BF0008 ;LDA $010800,X SWAP1 HEX 01 STA $0800,X PLA HEX 9F0008 ;STA $010800,X SWAP2 HEX 01 INX CPX XLEN BNE SLOOP RTS CODEFLAG ENT DFB 00