New Expansion Module Brings Standard Slots To Ancient Laptop

An expansion board with two 8-bit ISA slots plugged into a Sharp laptop

Upgrading and repairing vintage laptops is often a challenge — even if their basic hardware is compatible with ordinary PCs, they often use nonstandard components and connectors due to space constraints. The Sharp PC-4600 series from the late 1980s is a case in point: although it comes with standard serial and parallel ports, the only other external interface is a mysterious connector labelled EXPBUS on the back of the case. [Steven George] has been diving into the details of this port and managed to design a module to turn it into a pair of standard ISA ports.

Apparently, no peripherals were ever released for the EXPBUS port, so reverse-engineering an existing module was out of the question. [Steven] did stumble upon a service manual for the PC-4600 however, and as it turned out, the connector carried all the signals present in an 8-bit ISA bus. Turning it into something useful was simply a matter of designing an adapter board with the EXPBUS connector on one side and regular ISA slots on the other.

An expansion board plugged into a laptop, carrying two ISA cardsThe board also has an external power connector, to avoid overloading the laptop’s internal power supply, as well as a couple of buffer capacitors to smooth out the power rails. [Steven] tested the expansion board with a network adapter and a sound card, and it appears to be functioning well. It should be noted that only the +5 V power rail is available by default, so if any cards need +12 V or any negative rail, those should be provided externally.

Gerber files for this project are available on [Steven]’s website, so if you’ve got one of these machines lying around, now might be the time to upgrade it. This isn’t the first expansion for the PC-4600 series that [Steven] developed, either: he also designed an external floppy drive adapter that should ease data transfer with other PCs.

It’s great to see how the hacker community keeps classic portables like this one alive: one day it might also need a broken screen replaced or a dodgy power supply repaired.

10 thoughts on “New Expansion Module Brings Standard Slots To Ancient Laptop

    1. I would argue that since we still use the x86 architecture from 1978, 30 years ago is not that old.

      I would consider anything before the 1978 old history,
      and anything before the first minicomputer in 1965 for ancient history.

      or one could also argue that anything older than Unix epoch (January 1, 1970) is ancient history.

      Without specifying what standard, one would assume the current standard (PCI express)
      so, while I do not agree there is no substance, I think this news title could have been better:

      “New module brings ISA expansion to old Sharp PC-46xx series Laptops.”

      1. That wasn’t the point, I assume. The point was that computer technology is a fast-paced business/field. At least in comparison to others.

        Back in the 90s, technology was evolving so fast, that a PC was obsolete after a couple of months. Bus systems came and went, overdrive CPUs were being sold, etc.

        To give an idea, 12 MHz 80286 at the beginning of the 90s vs Pentium III at 733 MHz by the end of the 90s.
        In computing, this evolutionary gap was massive.

        So I think that “ancient” and “relic” and “antique” are valid terms in this context. Their actual usage depends on the Zeitgeist, also. Point of views can change, terminology can change, definitions can change. It’s all relative. Maybe your definition of then simply is from another time? πŸ€·β€β™‚οΈ

        1. you can still buy brand new industrial computers using 386/486 chips with ISA bus.

          obsolete, relic and museums piece is points of view, and antique is also usable for
          mass produced manufactured products. (otherwise it implies its over 100 years old)

          but the word ‘ancient’ is normally used in the sense of ‘prehistoric’ or ‘earliest’.
          ergo; ‘prehistoric: as in pre home computer, or ‘earliest’ as in minicomputer.

          you could actually call a modern EV for ancient technology,
          as it predates gasoline (1832 vs 1886) and is the earliest (not including steam).

          and it can also be used humorous as; ‘showing or feeling signs of age or wear’.

          so your right, I used the older (but still valid definition), as “new expansion module brings standard slots to laptop showing signs of age and wear”, is an even worse title.

      2. β€œNew module brings ISA expansion to old Sharp PC-46xx series Laptops.”

        Not quite. MS-DOS and Windows 3.1 era PCs are museums pieces, period.
        As hard this may to accept for some of us.

        A, say, 486DX2-66 PC with VLB graphics belongs next to a PDP-11, an IMSAI 8080, a Commodore C64, Atari ST or SGI Indy graphics workstation.

        Likewise, the Atari 2600, Colecovision, Vextrex, Nintendo NES, Turbo Grafx 16, Nintendo Gameboy, Super Nintendo, Sega Genesis, Atari Lynx, Philips 3DO, N64 or Sega Dreamcast etc are all museums pieces by now.

        And I think we must learn to cope with this fact. Time goes on. Things we used to merely consider being “a little bit old” are now history.

        There are teens out there who never had held a VHS cassette in their hands, who never had used a stationary, wired telephone with buttons and pulse/tone dial – yet alone a rotaty phone. Or who never had seen an incandescent lamp blowing, who never had seen a night sky with bright stars. Think about it. Please.

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