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Thread: Help to ID an unknown 16-bit ISA board (Curtis INC ROMRISK PCM2, 1993)?

  1. #1
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    Default Help to ID an unknown 16-bit ISA board (Curtis INC ROMRISK PCM2, 1993)?

    Hello.

    Included in a local auction with couple misc. ISA boards, I got this mystery board, see photos below (sorry for the potato-quality).

    Can anyone shed any light on what it might be? My google-fu failed me and I can't find any leads on this.

    The board says: "CURTIS INC. TM ROMDISK PCM2 PWB P/N C8000 Rev. C Copyright 1993". Sticker on the back reads "CS202068". The main IC is "Symphony SL82C365G", there are two 50-pin male headers and a high-density male header on the rear. And a beeper!

    The 50-pin headers make me think of SCSI, could this be some kind of SCSI controller and/or cache? Or by the name 'ROMDISK' - a software lock for a disk to make it read-only, perhaps?

    I haven't been able to test this in a computer yet!


  2. #2

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    Quote Originally Posted by MindWalker View Post
    Or by the name 'ROMDISK' - a software lock for a disk to make it read-only, perhaps?
    A hardware lock more likely. I don't know these such old, but similar cards do exist for IDE and SATA that act as a pass-thru and filter out any commands that would cause data on the drive to get changed. These were used for forensic purposes. This could be such a card for SCSI, but I'm not sure if this was a thing already in 1993..?

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    The SL82C365 appears to be a 386/486 cache controller

    The SL82C365 supports direct-mapped cache system with data size ranged from 16KB to 1MB and line size ranged from 1 to 4 doublewords.
    Without any external logic, SL82C365 supports 1 to 4 banks of cache SRAMs independent of the line size. An 8-bit tag comparator is
    integrated into the chip which not only saves on the system cost but also improves the overall performance. 25ns tag SRAM and 35ns data
    SRAM are adequate for zero wait state non-pipelined 33Mhz operation. Assuming 8Kx8, 16Kx4, 32Kx8 and 64Kx4 SRAMs are used for
    tag SRAM, the selectable organization is indicated in Table 1-1. [see datasheet] More options are available for data RAM configurations
    because of the flexibility in selecting the number of banks. Refer to section 1.13 [see datasheet] for detailed design examples.
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  4. #4

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    Unlikely to be a cache controller card, however. "ROMDISK" and no RAM on the card (nor any way to add RAM) kind of rules that out. For a forensic card, you would need such a cache-controller chip as well, as it needs to buffer and modify commands send to the drive.

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    Curtis (including this model, the PCM) made sold-state drive emulators and was well-known for that up until about 2000. Note the ad here.

    I suspect that what you've got is only half of a product--the memory probably plugs into those 50 pin connectors, but that's just a guess. Either that, or this device uses external memory (through the bracket connector) and the interface is SCSI.

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    Thanks for the ideas!

    If the 50-pin connectors were SCSI, I'd say the board looks rather sparse to be a full SCSI controller. Perhaps it's just a pass-thrue thing (requiring a separate SCSI controller and a SCSI drive) with either write-protection or just cache?

    The external connector looks like it has 100 pins.

    Regarding the PCM2 name, and the ad linked by Chuck, I started looking at ISA-PCMCIA adapters, and here is one from another manufacturer, and it seems to use 2x50-pin connection to a 3,5" bay PCMCIA box. That board looks much smaller, but the general idea seems to match.

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    found this snippet

    Curtis Milestones from SSD Market History

    In 1985 - Curtis introduced the ROMDISK, the first SSD for the original IBM PC.
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    Also found this

    curtis.jpg

    Seems as if the Romdisk allowed a PC to run diskless.
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