Portable SCSI Products Performance Comparisons

The PortaSCSI/SCSICable Plus compares favorably to Adaptec/Trantor's MiniSCSI/EPP and Shuttle's Connection, Parallel to SCSI Adapter. Including the PortaSCSI, these selected products represent the highest performing portable interface adapters available, with the PortaSCSI, as shown below being the highest of all.

Hard Disk Access:

Benchmark tests were done utilizing a 486DX2 40mhz CPU, equipped with an Intel 82360SL I/O chip with EPP mode enabled. Daisy-chained to the SCSI interfaces were a IBM-DPEA31080 (1080MB) SCSI-II hard drive and a Toshiba XM-4100A portable CD-ROM drive. The Toshiba CD-ROM provided the termination power. The benchmarks were established using PC Magazine's Benchmark Series 6.0 - File Access, Large Records tests. Units of performance are bytes / second.

Manufacturer             PSS, Inc.        Adaptec         Shuttle
Product                  PortaSCSI        MiniSCSI/EPP    Connection
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16 Records of 16k bytes  ave. 419k        ave. 365k       ave. 380k
---------------------------------------------------------------------------
    File Creation               280k             256k            273k
    Sequential Write            430k             340k            356k  
    Sequential Read             562k             527k            541k 
    Random Read                 403k             338k            352k
---------------------------------------------------------------------------
8 Records of 32k bytes   ave. 484k        ave. 433k       ave. 448k
---------------------------------------------------------------------------
    File Creation               306k             280k            292k
    Sequential Write            531k             421k            432k
    Sequential Read             579k             533k            549k 
    Random Read                 523k             498k            518k

Conclusion: PSS's PortaSCSI / SCSICable Plus outperforms competitors by 10% or more, consistently.

CD-ROM Access: Benchmarks done with the CDSPEED Benchmark 1.0 from Microsoft, for data streaming transfer rate.

Manufacturer             PSS, Inc.        Adaptec         Shuttle
Product                  PortaSCSI        MiniSCSI/EPP    Connection
Total Data Read          2240kb           2240kb          2240kb 
Overall transfer rate    299.4kb/second   262kb/second    266kb/second
Total CPU utilization    33.1%            47.5%           48.5%

Portable SCSI Products Physical Comparison:

Manufacturer             PSS, Inc.         Adaptec            Shuttle
Product                  PortaSCSI         MiniSCSI/EPP       Connection
------------------------------------------------------------------------------
Integrated Cable Design  YES               YES                YES
ASIC Chipset             custom CMOS       Actel A1010A PLCC  custom
SCSI Chipset             NCR53c80          NCR53c400          Not Available
Termination Power        YES               NO                 YES
SCSI Connector           MD 50 or          Centronics 50      MD 50 or
SCSI Connector           Centronics 50     -                  Centronics 50
Auxilary +5V jack        YES               NO                 YES
Lowest Operating         3.6V              4.75V              5.00V
 Voltage(TERMPOWER)
Current Consumption      lowest            approx. 60ma       <65ma(Highest)
Daisy Chain Clearance    Enough            NO                 Enough
Single Deck Design for   YES               NO                 In middle of 
 printer pass through                                         assembly 
 port 
Manufacturing and Cable  Cable with IDC    Hand Soldering 25  Soldering to  
 Soldering Techniques     connector plug    lines into board   DB25
List Price               $ 199.00          $ 249.00           $ 199.00
CorelSCSI II Drivers     YES               NO                 NO

Conclusions:

PortaSCSI/SCSICable Plus provides the best performance with a sleeker, simpler design. The PortaSCSI offers both older centronics 50 position (SCSI-I) as well as microdensity 50 position (SCSI-II) solutions. The sleek design allows for a single deck with enough clearance to allow for "daisy-chains" of peripherals. The PortaSCSI was designed as the hardware test component for the SCSITool Box software (over 8,000 installations) used for SCSI bus testing and can co-exist with other SCSI adapters on the same bus (multiple hosting). Adaptec and Shuttle can not provide support for a host with a existing SCSI bus (i.e. Texas Instruments Notebooks, as well as a large percentage of desktop DOS/Windows hosts).

Verse Adaptec; The PortaSCSI-II also provides for auxiliary +5V (great for certain devices, like 8mm tape drives), this is not available from Adaptec. The PortaSCSI provides complete SCSI bus functionality whereas Adaptec's does not (including multiple initiators on same bus). The PortaSCSI's parallel to SCSI arbitration is much more elegant allowing better CPU utilization. At CD-ROM data rates (300KB to 600KB/s) PortaSCSI is MPC-II compliant whereas Adaptec's CPU utilization is not within that specification. With the capabilities of Corel SCSI Version-2, the PortaSCSI provides a complete, attractive solution, and at equal or lower prices than any competitive product.

Verse Shuttle; The PortaSCSI-II is faster while being more efficient. At similar data rates PSS's PortaSCSI is much more elegant in CPU utilization, being MPC-II compliant (whereas at similar CD-ROM data rates of 300-600KB/s Shuttle's Connection interface is not). PSS design requires and consumes much less current than the Shuttle Connection.