Tape

BlueSCSI can emulate a SCSI sequential access device (tape drive), allowing vintage computers to read and write tape images stored on the SD card.

Setup

Single Tape Image

Place a tape image file on the SD card root with the naming convention:

TP<id>_<blocksize>.<ext>

Examples:
- TP0_512.img - Tape on SCSI ID 0, 512-byte blocks
- TP3.tap - Tape on SCSI ID 3, default block size

Multi-File Tape (Directory-Based)

A directory can represent a tape with multiple file marks. Each file inside the directory is one tape section separated by file marks:

tp0 - my tape/
tape.000
tape.001
tape.002

• The directory name uses the same TP<id> prefix
• Files within the directory are enumerated in lexical order
• Each file boundary acts as a tape file mark
• Reading past a file boundary reports a filemark condition to the host, then automatically loads the next file

Configuration via bluescsi.ini

[SCSI0]
Type = tape
BlockSize = 512

The default SCSI inquiry response identifies as BLUESCSI TAPE. An Apple-specific variant (APPLE_TAPE) is used when Apple quirks are enabled.

Supported SCSI Commands

Standard SCSI commands (INQUIRY, MODE SENSE, MODE SELECT, REQUEST SENSE, TEST UNIT READY) are also supported through the common SCSI2SD layer.

Operations Detail

READ

Supports both fixed-length (multiple blocks per transfer) and variable-length (single block) reads. When reading across a file boundary in a multi-file tape, a filemark condition is reported to the host with a CHECK CONDITION status. The sense data info field reports how many blocks were NOT transferred, per SCSI-2 spec. The next read automatically begins from the following file.

WRITE

Writes data at the current tape position. Both fixed and variable-length writes are supported. Advances the tape position after writing. Write-protected tapes return WRITE PROTECTED sense.

SPACE

• Code 0 - Space by blocks: Move forward or backward a specified number of blocks
• Code 1 - Space by filemarks: Returns end-of-data condition
• Code 3 - Space to end-of-data: Returns BLANK CHECK sense

LOCATE / SEEK

Positions the tape to a specific block address. Simulates a 10ms seek delay. Validates the target position against tape capacity.

READ POSITION

Returns a 20-byte response including:
- Beginning-of-partition (BOP) flag when at position 0
- End-of-partition (EOP) flag when past the last block
- Current block position (32-bit, big-endian)

Mode Page 0x10 (Sequential Device Configuration)

Reports density code 0x13 (DAT Data Storage) with a 100ms write delay and auto-generation of end-of-data markers.

Limitations

• WRITE FILEMARKS is a stub - it reports success but does not create actual file mark boundaries in the image
• SPACE by filemarks does not iterate through marks; returns end-of-data
• VERIFY with byte compare is not supported (returns ILLEGAL REQUEST)
• No data compression support
• No partition support (single partition only)
• OMTI compatibility mode forces fixed-block reads/writes regardless of host request

Compatibility

The OMTI tape drive quirk mode is automatically applied for hosts that require it. In this mode, all read and write operations use fixed-block transfers regardless of what the host requests.