Andy "Rasteri" Tait Brings ISA Back with a Bang — By Abusing the TPM Slot on Modern Motherboards
Designed to connect to a modern motherboard where the Trusted Platform Module will go, the dISAppointment resurrects your old ISA cards.
Vintage computing enthusiast Andy "Rasteri" Tait has been working on an add-on to bridge the worlds of modern and classic computer hardware — by abusing the Trusted Platform Module (TPM) on most motherboards.
"This is a project I'm working on, it's an LPC [Low Pin Count] to ISA [Industry Standard Architecture] adapter," Tait explains of his creation, dubbed the dISAppointment — but proving anything but. "Basically, it allows you to connect old ISA cards like [a] Sound Blaster 16 up to modern motherboards."
Originally invented by IBM as the PC bus for its eponymous IBM PC, the Industry Standard Architecture (ISA) was taken by companies building IBM compatibles and turned into exactly that. For years it was the standard for add-in boards, until the 32-bit Peripheral Component Interconnect (PCI) bus took over. Today, it's a rare sign in consumer hardware —though, interestingly, still available in some industrial devices.
Brought to our attention by Adafruit, the dISAppointment brings ISA back to modern hardware — but eschews complexities like a PCI Express (PCIe) to ISA bridge chip in favor of making use of a little-known feature of the Trust Platform Module (TPM) socket. Found on most motherboards, the TPM socket is designed to house a security chip — but, hidden away in its feature list, is access to the otherwise-locked-away ISA bus still present in the motherboard southbridge chip.
In a demo of the board connected to an system with an Intel Core i5 quad-core processor, released in 2011, Tait shows a Creative Sound Blaster 16 ISA sound card running perfectly in DOS over the unveiled ISA bus. "If I just do the old standard Doom test," he says, "we have audio. That's full audio, music and sound effects."
While the documentation for the board has yet to be written, Tait has already published the hardware design files and software source code for the project to his GitHub repository under the reciprocal Creative Commons Attribution-ShareAlike 4.0 license.