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Routines |
| Prev: E931 | Up: Map | Next: E99F |
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One-shot startup trampoline. BASIC line 1 enters here via USR(VARS-74). It is not game logic: it finishes the load, replaces the decoy line 1 at PROG with the real opening from Bootstrap_Workspace, points BASIC at line 270F via NEWPPC (that line
GO TOs 15, then reclaims this stub with RECLAIM-1 and falls into the interpreter. It never returns from USR.
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Point IX at the machine stack and read the USR return word.
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| Run_Bootstrap | E933 | LD IX,$0000 | Clear IX. | |
| E937 | ADD IX,SP | Point IX at the machine stack. | ||
| E939 | LD A,(IX+$14) | Fetch the low byte of the USR return address into A. | ||
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Shuffle the USR return address and stash the reclaim start.
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| E93C | DI | Disable interrupts. | ||
| E93D | SLA (IX+$15) | Shift the high byte of the USR return address right. | ||
| E941 | SLA A | Shift the low byte of the USR return address left. | ||
| E943 | LD (IX+$14),A | Write the shuffled low byte back to the stack frame. | ||
| E946 | XOR (IX+$15) | Mix in the high byte of the USR return address. | ||
| E949 | PUSH BC | Stash the reclaim start address on the stack. | ||
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Prepare flags and timing for the pilot-tone search.
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| E94A | LD IX,$0001 | Set IX to 0001. | ||
| E94E | AND A | Clear the carry flag. | ||
| E94F | SCF | Set the carry flag. | ||
| E950 | EX AF,AF' | Switch to the shadow flags. | ||
| E951 | LD C,$22 | Set the EAR/border state in C to 22. | ||
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Listen for six double edges that look like a pilot pulse.
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| Run_Bootstrap_Detect_Pilot | E953 | LD E,$06 | Set the pilot pair count in E to 06. | |
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Timing loop body.
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| Run_Bootstrap_Detect_Pilot_Loop | E955 | LD B,$9C | Set the timing constant in B to 9C. | |
| E957 | CALL $05E3 | Call LD-EDGE-2. | ||
| E95A | JR NC,Run_Bootstrap_Detect_Pilot | Jump back to Run_Bootstrap_Detect_Pilot if the carry flag is reset. | ||
| E95C | LD A,$C6 | Jump back to Run_Bootstrap_Detect_Pilot if B is at least C6. | ||
| E95E | CP B | |||
| E95F | JR NC,Run_Bootstrap_Detect_Pilot | |||
| E961 | DEC E | Decrease the pilot pair count by one. | ||
| E962 | JR NZ,Run_Bootstrap_Detect_Pilot_Loop | Jump to Run_Bootstrap_Detect_Pilot_Loop until the pilot pair count is zero. | ||
| E964 | INC E | Increase the pilot pair count by one. | ||
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Prepare the data-block load into Bootstrap_Workspace.
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| E965 | LD A,$FF | Set A to FF to indicate this is a data block, not a header. | ||
| E967 | SCF | Set the carry flag (load, do not verify). | ||
| E968 | EX AF,AF' | Switch to the shadow flags. | ||
| E969 | LD DE,$0047 | Set the block length in DE to 0047 bytes. | ||
| E96C | LD IX,$5B01 | Point the load destination in IX at Bootstrap_Workspace. | ||
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Load the data block via LD-SYNC.
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| E970 | CALL $058F | Call LD-SYNC. | ||
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Apply the workspace patch and hand control back to BASIC.
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| Run_Bootstrap_Apply | E973 | DI | Disable interrupts. | |
| E974 | LD DE,($5B3F) | Fetch the reclaim end address into DE from Bootstrap_Reclaim_End. | ||
| E978 | JR Run_Bootstrap_Apply_Body | Jump to Run_Bootstrap_Apply_Body. | ||
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Set NEWPPC from the loaded workspace.
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| Run_Bootstrap_Apply_Body | E97A | LD HL,($5C53) | Fetch PROG into HL. | |
| E97D | EX DE,HL | Exchange DE and HL. | ||
| E97E | LD BC,($5B41) | Write *Bootstrap_New_Line to *NEWPPC. | ||
| E982 | LD ($5C42),BC | |||
| E986 | LD (IY+$0A),$00 | Clear NSPPC. | ||
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Copy the workspace over PROG.
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| E98A | LD HL,$5B01 | Copy 3E bytes from Bootstrap_Workspace over *PROG. | ||
| E98D | LD BC,$003E | |||
| E990 | LDIR | |||
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Seed HL' and enable interrupts.
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| E992 | EXX | Switch to the shadow registers. | ||
| E993 | LD HL,$2758 | Set HL' to 2758. | ||
| E996 | EXX | Switch back to the normal registers. | ||
| E997 | EI | Enable interrupts. | ||
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Reclaim this stub via RECLAIM-1.
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| E998 | POP DE | Restore the reclaim start address into DE from the stack. | ||
| E999 | LD HL,($5C4B) | Fetch VARS into HL (reclaim end). | ||
| E99C | JP $19E5 | Jump to RECLAIM-1. | ||
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