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Groundwork for loading local disk images in PCjs

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This commit is contained in:
Jeff Parsons 2014-11-09 18:57:13 -08:00 • committed by jeffpar
commit 43860a588c
20 changed files with 1355 additions and 1157 deletions
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36
my_modules/shared/lib/diskapi.js
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@ -72,4 +72,38 @@ var DiskAPI = {
}
};
if (typeof module !== 'undefined') module.exports = DiskAPI;
/*
* Common (supported) diskette formats
*/
DiskAPI.DISKETTE_FORMATS = {
163840: [40,1,8], // media type 0xFE: 40 cylinders, 1 head (single-sided), 8 sectors/track, ( 320 total sectors x 512 bytes/sector == 163840)
184320: [40,1,9], // media type 0xFC: 40 cylinders, 1 head (single-sided), 9 sectors/track, ( 360 total sectors x 512 bytes/sector == 184320)
327680: [40,2,8], // media type 0xFF: 40 cylinders, 2 heads (double-sided), 8 sectors/track, ( 640 total sectors x 512 bytes/sector == 327680)
368640: [40,2,9], // media type 0xFD: 40 cylinders, 2 heads (double-sided), 9 sectors/track, ( 720 total sectors x 512 bytes/sector == 368640)
737280: [80,2,9], // media type 0xF9: 80 cylinders, 2 heads (double-sided), 9 sectors/track, (1440 total sectors x 512 bytes/sector == 737280)
1228800: [80,2,15], // media type 0xF9: 80 cylinders, 2 heads (double-sided), 15 sectors/track, (2400 total sectors x 512 bytes/sector == 1228800)
1474560: [80,2,18], // media type 0xF0: 80 cylinders, 2 heads (double-sided), 18 sectors/track, (2880 total sectors x 512 bytes/sector == 1474560)
2949120: [80,2,36] // media type 0xF0: 80 cylinders, 2 heads (double-sided), 36 sectors/track, (5760 total sectors x 512 bytes/sector == 2949120)
};
/*
* BIOS Parameter Block (BPB) offsets in DOS-compatible boot sectors
*/
DiskAPI.BPB = {
JMP_OPCODE: 0x00, // 1 byte for a JMP opcode, followed by a 1 or 2-byte offset
OEM_STRING: 0x03, // 8 bytes
SECTOR_BYTES: 0x0B, // 2 bytes: bytes per sector (eg, 0x200 or 512)
CLUSTER_SECS: 0x0D, // 1 byte: sectors per cluster (eg, 1)
RESERVED_SECS: 0x0E, // 2 bytes: reserved sectors; ie, # sectors preceding the first FAT--usually just the boot sector (eg, 1)
FAT_TOTAL: 0x10, // 1 byte: FAT copies (eg, 2)
ROOT_ENTRIES: 0x11, // 2 bytes: root directory entries (eg, 0x40 or 64) 0x40 * 0x20 = 0x800 (1 sector is 0x200 bytes, total of 4 sectors)
SECTOR_TOTAL: 0x13, // 2 bytes: number of sectors (eg, 0x140 or 320)
MEDIA_TYPE: 0x15, // 1 byte: media type (eg, 0xFF: 320Kb, 0xFE: 160Kb, 0xFD: 360Kb, 0xFC: 180Kb)
FAT_SECS: 0x16, // 2 bytes: sectors per FAT (eg, 1)
TRACK_SECS: 0x18, // 2 bytes: sectors per track (eg, 8)
HEAD_TOTAL: 0x1A, // 2 bytes: number of heads (eg, 1)
HIDDEN_SECS: 0x1C, // 4 bytes: number of hidden sectors (always 0 for non-partitioned media)
LARGE_SECS: 0x20 // 4 bytes: number of sectors if SECTOR_TOTAL is zero
};
if (typeof module !== 'undefined') module.exports = DiskAPI;