So you’re limited in what you can emulate. Depending on what you’re doing, you may wind up holding IOCHRDY low on the ISA bus low for a long time, effectively halting ISA bus. PIO does help an awful lot with handling events on the ISA bus but as soon as the M0 ARM cores on the RP2040 get involved things can slow down a lot. There are a few tradeoffs with “simply” using an RP2040. It was mentioned in a Hackaday post a while ago about a project inspired by it that emulates an NE2000 card in a PCMCIA card with a Pico: It was originally created to emulate a Gravis Ultrasound but I also have Adlib and MPU-401 support in the works. Posted in Retrocomputing Tagged emulation, fpga, isa bus, sound card Post navigation Of course, you could take the concept to its logical extreme and simply implement an entire PC in an FPGA. This approach could also come in handy to replace other unobtanium hardware, like rare CD-ROM interfaces. The sound cards currently supported include AdLib, 8-bit SoundBlaster, Gravis Ultrasound and Roland MT-32, but any card that’s documented well enough could be emulated. By emulating a hard drive and sound card on the Pi he is able to run a variety of classic DOS games with full sound effects and music. In the videos embedded below you can see demonstrating the system on a 386 motherboard that only has a VGA card to hook up a monitor. The Pi’s multi-core architecture allows it to run several of these tasks at once while still keeping up the reasonably high data rate required by the ISA bus. ’s current repository contains code for several sound cards as well as a hard drive and a serial mouse. The FPGA connects to the ISA bus and implements its bus architecture, while the Pi communicates with the FPGA through its GPIO ports and emulates any card you want in software. It contains a design for a simple ISA plug-in card that hooks up to a Cyclone IV FPGA and a Raspberry Pi. So what can you do if your favorite ISA card is not easily available? One option is to head over to ’s GitHub page and check out his FrankenPiFPGA project. Although ISA has been obsolete for most purposes since the late 1990s, some ISA cards such as high-quality sound cards have become so popular among retrocomputing enthusiasts that they now fetch hundreds of dollars on eBay. Any manufacturer could design plug-in cards or even entire computers that were hardware and software compatible with the IBM PC. It may not feature a physical computer, but it can be a time saver, and a bit of a game changer in some scenarios.One of the reasons the IBM PC platform became the dominant standard for desktop PCs back in the mid-1980s was its open hardware design, based around what would later be called the ISA bus. Raspberry Pi fans love to play and tinker. Virtualization is just another way of looking at things.It's also good practice to test a new operating system in a virtualized environment. Making screenshots on the Raspberry Pi is simple enough but exporting them can be tricky-virtualization circumvents that. This might be useful to children using Scratch or other development tools. A virtual Raspberry Pi offers the chance to gauge how the various apps will run.Further, virtualization gives anyone wanting to dip a toe in the pie (!) a quick chance to do so. All the messing around that is involved with writing a disk image to SD is avoided. Using a virtualized Raspberry Pi environment lets you try out the operating system with little effort.
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