; ============================================================================= ; Final handoff 13A9h → JP FF4Ch (type-21h SYSTEM load success) ; Source: VECTOR 4/8086 - V2_AC_Interleaved_XHE_XHO.bin ; CPU: Z80 | base: 0000h ; See also: docs/06-handoff-13A9-FF4C.md ; docs/07-dual-cpu-architecture.md (8086 prep, port 02, ROM scan) ; Callers: JP 13A9 @11BD (type21), vector 002A ; ; Dual-CPU notes: ; - This ROM has NO 8086 machine code (padding FF then 00 only after 16DB). ; - 67F0 gets EA + far ptr from SYSTEM file (8086 JMP FAR image). ; - Stub @0573 does OUT (02),01 — only port-02 write in entire ROM; ; 13A9 copies stub to 674C but does NOT call it; primary transfer is JP FF4C. ; ============================================================================= ; --- 13A9: build OS parameter block @67E0 --- 13A9 2160fe LD HL, FE60h 13AC 22e467 LD (67E4h), HL ; high ptr FE60 13AF 2100fe LD HL, FE00h 13B2 22e067 LD (67E0h), HL ; high ptr FE00 13B5 2afb0f LD HL, (0FFBh) ; ROM word (dump: FFFF) 13B8 22e867 LD (67E8h), HL 13BB 210002 LD HL, 0200h 13BE 22ea67 LD (67EAh), HL 13C1 3e48 LD A, 48h 13C3 32ec67 LD (67ECh), A 13C6 217305 LD HL, 0573h ; ROM stub source 13C9 114c67 LD DE, 674Ch ; RAM stub dest 13CC 011200 LD BC, 0012h ; 18 bytes 13CF edb0 LDIR ; copy Z80 handoff stub 13D1 210ce4 LD HL, E40Ch 13D4 22ee67 LD (67EEh), HL 13D7 3eea LD A, EAh ; 8086 JMP FAR opcode 13D9 32f067 LD (67F0h), A ; 67F0: EA; 67F1/F3 from file 13DC 3add5f LD A, (5FDDh) ; RAM size flag from cold boot 13DF 32f567 LD (67F5h), A 13E2 b7 OR A 13E3 210010 LD HL, 1000h ; small RAM base 13E6 2803 JR Z, 13EBh 13E8 210030 LD HL, 3000h ; large RAM base 13EB 22e267 LD (67E2h), HL 13EE 22e667 LD (67E6h), HL 13F1 2818 JR Z, 140Bh ; small: skip swap ; --- large RAM: swap 8 bytes 67F0 ↔ 77F0 under bank 3F --- 13F3 163f LD D, 3Fh 13F5 cd3604 CALL 0436h ; OUT (16), ~3F 13F8 0608 LD B, 08h 13FA 21f067 LD HL, 67F0h 13FD 11f077 LD DE, 77F0h 1400 1a LD A, (DE) 1401 4e LD C, (HL) 1402 77 LD (HL), A 1403 79 LD A, C 1404 12 LD (DE), A 1405 23 INC HL 1406 13 INC DE 1407 10f7 DJNZ 1400h 1409 3e01 LD A, 01h ; mark large-RAM path in A ; --- mapper rebuild then JP FF4C --- 140B 08 EX AF, AF' ; save A (0/1) for epilogue 140C 0e16 LD C, 16h ; mapper port 140E 1600 LD D, 00h ; bank index 1410 0600 LD B, 00h ; window base step 1412 7a LD A, D 1413 2f CPL 1414 ed79 OUT (C), A ; OUT (16), ~D 1416 78 LD A, B 1417 c608 ADD A, 08h 1419 47 LD B, A 141A ca4cff JP Z, FF4Ch ; ★ transfer: B wrapped F8→00 141D 14 INC D 141E fef0 CP F0h ; A still = B after ADD 1420 2004 JR NZ, 1426h 1422 16ce LD D, CEh ; video/attr bank slot 1424 18ec JR 1412h 1426 fef8 CP F8h 1428 20e8 JR NZ, 1412h ; B==F8: epilogue — one more map then next ADD wraps to JP FF4C 142A 08 EX AF, AF' 142B b7 OR A ; Z if small RAM path 142C 163f LD D, 3Fh 142E 28e2 JR Z, 1412h ; final OUT ~3F = C0h 1430 167f LD D, 7Fh ; large: final OUT ~7F = 80h 1432 18de JR 1412h ; After final OUT, B becomes 00 → JP FF4C. ; FF4C is NOT in this ROM (image ends 1FFF). Runs loaded SYSTEM under new map. ; ============================================================================= ; Stub source @0573 (copied to 674C) — not executed by 13A9 itself ; ============================================================================= 0573 3e01 LD A, 01h 0575 d302 OUT (02h), A ; dual-CPU / bus signal 0577 0600 LD B, 00h 0579 3e00 LD A, 00h 057B 2f CPL ; A=FFh 057C 0e16 LD C, 16h 057E ed79 OUT (C), A ; OUT (16), FFh 0580 db0c IN A, (0Ch) 0582 c30000 JP 0000h ; re-enter 0000 under new map ; ============================================================================= ; Related: 0436 bank select (used by swap and bulk load) ; ============================================================================= 0436 c5 PUSH BC 0437 0e16 LD C, 16h 0439 0670 LD B, 70h 043B f5 PUSH AF 043C 7a LD A, D 043D 2f CPL 043E ed79 OUT (C), A ; OUT (16), ~D 0440 f1 POP AF 0441 c1 POP BC 0442 c9 RET ; ============================================================================= ; Related: 0420 bulk-load page → bank + HL in 7000 window ; ============================================================================= 0420 7b LD A, E 0421 e607 AND 07h ; page low 3 bits → 256B offset index 0423 0603 LD B, 03h 0425 b7 OR A 0426 cb1a RR D 0428 cb1b RR E ; DE >>= 1, thrice → bank = page>>3 042A 10f9 DJNZ 0425h 042C 53 LD D, E ; bank in D for 0436 042D cd3604 CALL 0436h 0430 210070 LD HL, 7000h 0433 84 ADD A, H ; H = 70 + (page&7) 0434 67 LD H, A ; HL = 7X00h 0435 c9 RET ; ============================================================================= ; 67xx layout after 13A9 (summary) ; ============================================================================= ; 67E0 FE00 ; 67E2 1000 or 3000 (5FDD) ; 67E4 FE60 ; 67E6 same as 67E2 ; 67E8 (0FFB) dump FFFF ; 67EA 0200 ; 67EC 48 ; 67EE E40C ; 67F0 EA + [offset @67F1 from file] + [seg @67F3 from file] ; 8086 JMP FAR image ; 67F5 (5FDD) ; 67F6 00 ; 674C 18-byte stub from 0573