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40 lines
1.6 KiB
40 lines
1.6 KiB
RESBDOS3.SPR and BNKBDOS3.SPR have been replaced
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with versions from the Jon Saxton disassembly with
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fixes distribution. The file called zpm3fix.txt
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have been included and details the fixes.
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ZPMLDR has also been updated with the version from
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the Jon Saxton disassembly. However, it has additionally
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been updated to correct an issue that was preventing
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RomWBW from booting under ZPMLDR.
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ZPMLDR has a slightly modified version of the rdSeq
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procedure (compared to CPMLDR). It appears that this
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causes deblocking to be bypassed on the initial disk
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read of CPM3.SYS. As a result, the entire disk sector
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(512 bytes) is read starting at 0x0080. This winds up
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overlaying 0x180 bytes of the start of ZPMLDR.COM causing
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it to fail catastrophically.
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According to the documentation at the top of zpm3ldr.z80,
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zpmldr is normally loaded from system tracks to address
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0x0400. In that scenario, the read of the entire sector
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would not overlay the start of the application. So, I
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suspect this is why this (bug?) is not relevant to many
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implementations.
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The ZPM3LDR.REL file used here has been modified to
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sync the rdSeq procedure back to the DIR CPMLDR version.
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This seems to allow ZPMLDR to work with RomWBW now.
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--WBW 4:22 PM 12/8/2021
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Jose Luis reported that attempting to change to a different
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DU by using a named directory was not working correctly.
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It was working with the original ZPM3 distribution, but not
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with the Jon Saxton patches. Refer to the RomWBW Issue
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https://github.com/wwarthen/RomWBW/issues/324. I was able
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to track down the issue and have applied an additional
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patch to correct the Jon Saxton variant.
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--WBW 8:46 PM 3/12/2023
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