- Inside Macintosh, Volume IV (1986), chapter 31 (esp. p.292); https://vintageapple.org/inside_o/pdf/Inside_Macintosh_Volume_IV_1986.pdf
This is a very rare format, developed for use on SCSI hard drives attached to the Macintosh Plus.
It was used before APM, and only gets a passing notice in later documentation. For example,
Inside Macintosh: Devices notes on page 3-25, in the definition of the pmSig field:
The partition signature. This field should contain the value of the pMapSIG constant ($504D). An earlier but still supported version uses the value $5453.
I refer to this as the "TS" partition format because of the signature word.
Block zero holds a Driver Descriptor Record that is nearly identical to the
APM definition, lacking only the ddPad definition (which defines drivers
beyond the first).
Block 1 holds the Device Partition Map:
$00 / 2: pdSig - signature (big-endian $5453, 'TS')
$02 / 4: pdStart - block number of first block of partition
$06 / 4: pdSize - number of blocks in partition
$0a / 4: pdFSID - file system ID ($54465331 'TFS1' for Macintosh Plus)
The pdStart/pdSize/pdFSID fields are repeated for successive partitions. There is no count,
so the list is supposed to end when all three values are set to zero.
Looking at a very old CD-ROM image:
00000200: 5453 0000 0022 0004 a5ba 5446 5331 0000 TS..."....TFS1..
00000210: 0000 4456 6572 0003 0002 6420 696e 746f ..DVer....d into
00000220: 2069 7473 656c 6620 6f72 2069 7473 206f itself or its o
00000230: 776e 2066 6f6c 6465 722e 3654 6861 7420 wn folder.6That
The first partition is start=$00000022 size=$0004a5ba fsid=TFS1. The second partition would have a start block of zero, which apparently ends the list. The rest of the data in the block is garbage.