Tech Jargon

Here's a listing of Controller Abbreviations (Jargon) used in TheRef(tm)
Interface -- What does the Controller use to control the Hard Drive?
  • ST506/412 -- The original HD interface, in MFM or RLL flavors. Named after the first two drives that adapted it, the ST506, and the ST412. The controlling electronics were split between the drive and a seperate plug-in board.
  • ESDI -- Enhanced Small Device Interface. Tried to overcome many of the limitations of the "standard" ST506/412 interface by improving the transmission of the data to the drive, and increasing the amount of control over the drive.
  • SASI -- Shugart Associates Standard Interface. Forerunner to SCSI, and basically the same. It moved controler functions onto the Drive, and used an 8-bit parallel data stream.
  • SCSI -- Small Computer Systems Interface. SASI developed into SCSI while waiting for IEEE approval. It features improvements to SASI derived from the IPI interface. It has it's own language and command set, which has been added to with each subsequent proposal (SCSI-1, SCSI-2, & SCSI-3). SCSI-1 was subject to too many "optional" commands, which hurt interoperability. (Each Manufacturer was free to pick & choose which commands it wished to support, and to add non-standard additional commands... ie: the "OCS" or OMTI Command Set, as opposed to the "CCS" or Common Command Set.)
  • ATA & XTA -- AT Attachment & XT Attachment. Originally designed to provide a more cost effective interface than SCSI or ESDI by integrating all the drive control electronics on the drive and eliminating costly additional boards. It eliminated the costly translation & communication electronics of SCSI and provided a simple interface to the system.
  • IPI -- Integrated Peripheral Interface. A high speed interface normally used on Minicomputers and above.
  • SMD -- Storage Module Device Interface. Another Minicomputer and up interface. Enhanced versions are SMD-E and SMD-O/E.
  • PS/2 -- Personal System/2 drive interface. An ATA interface which combined the normal ATA with the Power cable.
  • SSA -- Serial Storage Architecture.
  • FC-AL -- Fiber Channel-Arbitrated Loop.
  • PCMCIA -- A ATA interface adapted for PCMCIA cardslots.

    • Bus Supt -- What Bus does the card plug into, or attach to?

  • ISA(8) -- The 8-Bit PC or XT Compatible System Bus.
  • ISA(16) -- The 16-Bit AT Compatible System Bus.
  • EISA -- The Extended ISA System Bus.
  • VESA -- The VESA Local Bus.
  • PCI -- The Peripheral Component Interconnect Bus.
  • MCA(8), (16), or (32) -- The IBM MicroChannel System Bus (8, 16, or 32-bit).
  • NuBUS -- The Apple NuBUS System Component Bus.
  • SCSI -- The item attaches to or extends the SCSI bus.
  • none or blank -- The item does not directly attach to any bus.

    • EHD Floppy -- Does the card support Extra High Density 2.88MB floppys? (Y/N)

    Max Heads -- The maximum number of heads the controller can support (ST506/412 Interface).

    Max Cyls -- The maximum number of cylinders the controller can support (ST506/412 Interface).

    Interleave -- What's the tightest sector interleave that the controller can support? (1:1 being the tightest)

    ECC Length -- How many bits are used for the Error Correction Circuitry?

    Plug & Play Support -- Does this Peripheral support the new "Plug & Play" standard? (Y/N)

    Transfer Mode -- What method does the Controller use to transfer data from the Peripheral?

  • PIO -- Programmed I/O or CPU Assisted I/O -- The CPU directly clocks the transfer of each byte from the controller to System Memory. This method uses the most CPU resources, and durring transfers, interrupt servicing may be affected. For "Single-Tasking OSs, like DOS, where the System does little else while a transfer is taking place, PIO is the most cost effective mode. Under Multitasking OSs, PIO becomes a somewhat less effective choice.
  • DMA -- Direct Memory Access -- DMA tries to remove some of the load on the CPU by using the System DMA Controllers to transfer data from the Controller to the System Memory. However, most the the AT-type DMA Controller chips are rather slow, and the resulting transfer rate is often only slightly higher than the PIO method. CPU loading is reduced over the PIO method, but the higher costs have lead most Manufacturers to all but abandon simple DMA controllers.
  • B/M -- Bus Mastering or 1st Party DMA -- Bus Mastering Host Adapters (most are SCSI) take DMA to a higher level, circumventing the slow System DMA Adapters by using their own built-in High-Speed DMA chips. B/M HAs transfer their data by arbitraiting for control of the System Bus, then directly transferring the data into pre-allocated System Memory space. They need very little attention from the System CPU, so loading is very light, and other processes can continue in the System while transfers are taking place. For Multitasking OSs, B/M is the way to go. Most B/M Host Adapters also support advanced features, such as "Disconnect/Reconnect", where the HA can release the System Bus while it searches, then reconnects and transfers the requested information. Bus Mastering Host Adapters have one main drawback... they are much more expensive than simple PIO type Controllers.

    • Onboard BIOS -- Does this Peripheral have a BIOS? (Y/N)

    CoResident -- Will this Peripheral CoExist with a similar type of Peripheral? (Y/N) (ie: 2 HD Controllers, or 2 Floppy Controllers in the same System.)

    Hard Drive IC -- What IC is used to control the Hard Drive?

    Floppy Drive IC -- What IC is used to control the Floppys?

    Cache -- How many Bytes of Cache are on the Peripheral, or how much can be added? If it says 1KB-10MB, then the Peripheral comes with a minimum of 1KB, and can be expanded to 10MB.

    Length -- I've currently limited length measurements to a few "general" descriptions... 1/2, 2/3, 3/4, and FULL length.

    Height -- I've currently limited height measurements for Controllers to three... XT, AT, and MC. XT-height Peripherals are no higher than the screw-tab bend on the back-slot cover. AT-height Peripherals can extend past that bend to a maximum of about 1", or 25.4mm (Actually, the spec calls for slightly less.) MC is just a place-marker for MicroChannel height Peripherals, since their spec calls for only one maximum height.