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49 lines
1.5 KiB
TeX
49 lines
1.5 KiB
TeX
MP/M 1.0 *** Patch *** 10/17/79
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Page Zero Initialization with Bank Switched Memory
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__________________________________________________
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The following patch is required only if you have written
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an XIOS which supports bank switched memory. The nature of
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the problem is that the jump instruction at location 0000,
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at your interrupt entry points, and at the selected debugger
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breakpoint restart location must be initialized in each of
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your memory banks.
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The patch is performed in the SYSINIT procedure of your
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XIOS as follows:
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o Determine the BDOS base address by running GENSYS and
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then the MPMLDR. The MPMLDR will display the memory map
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showing the BDOS base address.
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o Once the BDOS base address has been determined, place the
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following instructions into your SYSINIT procedure:
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SYSINIT:
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...
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...
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; Loop through all banks
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LOOP:
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; Switch in the next bank
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MVI A,0C3H
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STA 0000H
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LXI H,BDOS+0091H
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SHLD 0001H
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STA BRKPTRST*8
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LXI H,BDOS+0101H
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SHLD BRKPTRST*8+1
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; Store appropriate jumps to your XIOS
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; for the interrupt entry points
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...
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JMP LOOP
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o Note that this patch requires that you leave the BDOS
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at the established base.
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