SCSI INQUIRY Command Analysis - SINTRAN III Limitations

Summary

SINTRAN III has NO vendor-specific restrictions for SCSI devices. The operating system only validates the Device Type field from the INQUIRY response. Vendor ID and Product ID fields are completely ignored by the driver.

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INQUIRY Command Usage in SINTRAN

When INQUIRY is Executed

INQUIRY (Function 42 or 36 in the driver API) is automatically performed when:

1. First access to an uninitialized LUN - Flag bit 5SCIN (bit 5 = SCSI INitialized) is checked
2. After UNIT ATTENTION with Sense Key 6 - Forces re-initialization
3. Explicit INQUIRY request from user applications (Function 75)

Source: IP-P2-SCSI-DISK.NPL:1124 and IP-P2-SCSI-DISK.NPL:1222

IF A=42 OR =36 GO FAR INQUI    % AUTOMATIC INQUIRY (line 1124)

CACOB: A:=L=:"HOME"
       IF SUTYP NBIT 5SCIN GO FAR INQUI     % START INQUIRY (line 3354)

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INQUIRY Response Processing

Step 1: Send INQUIRY Command

Location: IP-P2-SCSI-DISK.NPL:1222-1227

INQUI: SUTYP/\SMASK\/77400=:SUTYP           % ZERO OLD STATUS
       T:=SMBP1; X:=SMBP2                   % PHYSICAL ADDRESS OF COMMAND BUFFER
       11000; *STATX 00; STZTX 10           % COMMAND (0x12 = INQUIRY)
       "SINBL" SHZ 11; *STATX 20            % ALLOCATION LENGTH
       *STZTX 30; STZTX 40; STZTX 50
       CALL EXINT; CALL SCEIO; CALL ERRFATAL; X:=:B

Step 2: Parse Device Type (Byte 0)

Location: IP-P2-SCSI-DISK.NPL:1230-1242

T:=SMBP1; X:=SMBP2+SINBS; *LDATX 00
A\/377/\SUTYP=:SUTYP                 % UPDATE DEVICE TYPE INFORMATION
IF A SHZ -10=0 OR =3 OR =4 THEN
   SUTYP BONE 5SCDA=:SUTYP           % DIRECT ACCESS DEVICE
   22400                             % READ CAPACITY
ELSE
IF A=1 THEN
   2400                              % READ BLOCK SIZE (Sequential)
ELSE
IF A=177 THEN
   T:=NOLUN; GO FAR ERREX            % NO SUCH LUN (0x7F)
ELSE
   SUSI3+1=:SUSI1; GO FAR INFIN      % SHIFT INSTRUCTIONS (other types)

Device Type Values Accepted:

Value (Octal)	Value (Hex)	Device Type	SINTRAN Action
0	0x00	Direct Access (Disk)	Marks as Direct Access, reads capacity
1	0x01	Sequential Access (Tape)	Reads block size
3	0x03	Printer	Marks as Direct Access
4	0x04	Write Once (Optical)	Marks as Direct Access, reads capacity
177	0x7F	No Device Present	Returns error "NO SUCH LUN"
Other	Other	Unknown	Continues with default settings

Step 3: NO VENDOR VALIDATION

Critical Finding: The SINTRAN SCSI driver DOES NOT READ or VALIDATE the following INQUIRY fields:

• Byte 8-15: Vendor Identification (8 ASCII bytes)
• Byte 16-31: Product Identification (16 ASCII bytes)
• Byte 32-35: Product Revision Level (4 ASCII bytes)

Evidence: Complete analysis of INQUI routine (lines 1222-1289) shows only byte 0 is read for device classification.

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Vendor Compatibility

Confirmed Working Devices

From scsi_inquiry_explained.md and historical documentation:

Vendor	Product	Device Type	Works?
NDMICROP	1375	Direct Access	Yes
TANDBERG	TDC 3600	Sequential (streamer)	Yes
OSI	LD 1200 SCSI	Write Once (optical)	Yes
NDCDC	EMD 97201 (736)	Direct Access	Yes
NDCDC	EMD 97201 (368)	Direct Access	Yes
NDSTK	2925	Sequential (magtape)	Yes
ARCHIVE	VIPER 150 21247	Sequential (streamer)	Yes

ANY Vendor Will Work

Conclusion: SINTRAN will accept ANY SCSI device from ANY vendor as long as:

1. Device responds to INQUIRY command (0x12)
2. Byte 0 (Peripheral Device Type) contains a valid value:
   • 0x00, 0x03, or 0x04 for disk-like devices
   • 0x01 for tape-like devices
3. Device implements standard SCSI-1 or SCSI-2 command set

Modern emulators can use ANY vendor string - SINTRAN ignores it completely.

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Implementation Recommendations for Emulators

C# Emulator Implementation

When implementing a SCSI disk/tape emulator for SINTRAN, the INQUIRY response should follow this format:

byte[] InquiryResponse = new byte[36];

// Byte 0: Peripheral Device Type
InquiryResponse[0] = 0x00;  // 0x00 = Direct Access Device
                             // 0x01 = Sequential Access Device (Tape)
                             // 0x04 = Write Once Device (Optical)

// Byte 1: Removable Media Bit (RMB)
InquiryResponse[1] = 0x00;  // 0x00 = Non-removable, 0x80 = Removable

// Byte 2: ANSI Version
InquiryResponse[2] = 0x01;  // SCSI-1 compliance

// Byte 3: Response Data Format
InquiryResponse[3] = 0x01;  // Standard INQUIRY response format

// Byte 4: Additional Length
InquiryResponse[4] = 31;    // Additional bytes (36 total - 5 header)

// Bytes 5-7: Reserved
InquiryResponse[5] = 0x00;
InquiryResponse[6] = 0x00;
InquiryResponse[7] = 0x00;

// Bytes 8-15: Vendor Identification (8 ASCII bytes, space-padded)
// SINTRAN IGNORES THIS - use any value
string vendor = "NDMICROP";  // Or "EMULATOR", "GENERIC", anything!
Array.Copy(Encoding.ASCII.GetBytes(vendor.PadRight(8)), 0, InquiryResponse, 8, 8);

// Bytes 16-31: Product Identification (16 ASCII bytes, space-padded)
// SINTRAN IGNORES THIS - use any value
string product = "Virtual Disk    ";
Array.Copy(Encoding.ASCII.GetBytes(product.PadRight(16)), 0, InquiryResponse, 16, 16);

// Bytes 32-35: Product Revision Level (4 ASCII bytes)
// SINTRAN IGNORES THIS - use any value
string revision = "1.00";
Array.Copy(Encoding.ASCII.GetBytes(revision), 0, InquiryResponse, 32, 4);

Recommended Values for Authenticity

For historical accuracy (optional - SINTRAN doesn't care):

For Hard Disks: - Vendor: "NDMICROP" (Norsk Data Micropolis) - Product: "1375 " (1.3GB SCSI disk) - Revision: "1.00"

For Tape Streamers: - Vendor: "TANDBERG" (Norwegian tape manufacturer) - Product: "TDC 3600 " (QIC tape streamer) - Revision: "1.00"

For Optical Disks: - Vendor: "OSI " (Optical Storage International) - Product: "LD 1200 SCSI " (Write-once optical) - Revision: "1.00"

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Critical Discovery: No Vendor Whitelisting

Unlike some operating systems (e.g., certain proprietary Unix systems that check for specific vendor strings), SINTRAN has no vendor whitelist or blacklist.

This means: - ✅ Modern SATA-to-SCSI bridges work - ✅ Generic SCSI emulators work - ✅ Virtual SCSI devices work - ✅ Any SCSI device that implements the basic command set works

The only requirement is correct SCSI command implementation, not vendor identity.

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INQUIRY-Related Error Codes

Error Code (Octal)	Error Name	Trigger Condition
NOLUN	No Such LUN	Device Type = 0x7F (No device present)
TYPER	Type Error	Device Type doesn't match expected type (checked later during operations)
ILSEN	Illegal Sense	Sense data format incorrect after INQUIRY failure
RQSER	Request Sense Error	Cannot retrieve sense after INQUIRY failure

Source: IP-P2-SCSI-DISK.NPL:1240-1242, 1207

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Testing Checklist for Emulators

When implementing SCSI device emulation for SINTRAN:

Minimum Requirements

• [ ] Respond to INQUIRY command (0x12) with 36-byte response
• [ ] Set byte 0 to correct device type (0x00 for disk, 0x01 for tape)
• [ ] Return CHECK CONDITION status if LUN doesn't exist (sets Device Type = 0x7F in sense)
• [ ] Implement READ CAPACITY for disk devices
• [ ] Implement READ/WRITE commands appropriate for device type

Optional (SINTRAN Doesn't Check)

• [ ] Set Vendor ID (bytes 8-15)
• [ ] Set Product ID (bytes 16-31)
• [ ] Set Revision (bytes 32-35)

Advanced Testing

• [ ] Test with INQUIRY returning device type 0x00 → Should work as disk
• [ ] Test with INQUIRY returning device type 0x01 → Should work as tape
• [ ] Test with INQUIRY returning device type 0x7F → Should return "NO SUCH LUN" error
• [ ] Test with INQUIRY returning device type 0x04 → Should work as optical disk
• [ ] Test changing Vendor ID to "GENERIC" → Should still work (SINTRAN ignores it)

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Related Source Code Files

File	Purpose
IP-P2-SCSI-DISK.NPL	Main SCSI disk driver with INQUIRY handling
IP-P2-SCSI-DRIV.NPL	Low-level SCSI protocol driver
scsi_inquiry_explained.md	INQUIRY command format reference
SCSI-controller.md	Hardware interface documentation

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Conclusion

SINTRAN III is vendor-agnostic for SCSI devices. The operating system performs zero validation of vendor strings, making it highly compatible with modern SCSI emulators, virtual devices, and generic SCSI hardware.

The only hard requirement is implementing the correct SCSI command set for the declared device type.

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Document Path: Source Code\Sintran L\NPL\SCSI-INQUIRY-Analysis.md

Analysis Date: 2025-10-13 Analyzer: Based on SINTRAN III NPL source code analysis