IC/component to replace 8255 in PCI bus


Thread Starter

sutono effendi

I want to make use of a PC to control small project. In old days we can design with 8255 to make PC control other things. However, all PCs nowadays do not come with ISA bus anymore. Anybody knows what IC/component can replace this 8255 in PCI bus?

Robert Scott

First of all, you can still buy industrial PCs with the ISA bus. See Kontron, for example. And if you must use the PCI bus, then you can buy various digital I/O cards from places like Measurement Computing or Metrabyte. Just don't expect to program the PCI boards at the register level. PCI is so complicated that the only option is to use the board manufacturer's driver library.

Robert Scott
Real-Time Specialties

Curt Wuollet

I have searched high and low for a "good" replacement for the 8255. This is an ancient chip and still used because nothing else really gives you this capability with one chip and at reasonable cost. It's not perfect, but it's well
understood and there are many examples of drivers. Several companies have ASICs or PALs but I haven't seen any for sale by themselves. The ISA bus is still fast enough for digital control in the PLC manner but the duopoly has decided it must go along with serial ports, to fuel new waves of planned obsolesense.

But I don't agree that vendors libraries are the only way for the PCI bus. PCI works well on Linux and did long before vendors provided any Linux libraries. What's missing is the information to write for PCI and the OSS community provides that also. So, even if you have to write for the monopoly, you still can
learn from the efforts of the community. Or better yet, check out the Linux Lab Project and others and simply use the source on Linux.

If you're looking for a PCI card, then Sealevel Systems (http://www.sealevel.com) offers several TTL products with 8255 mode 0 (zero) support. You'll need to use DOS or Linux if you want to communicate with the hardware directly. Otherwise, in Windows, you can communicate with the device using their driver. See if one of these fits your needs:

8008 - 24 channel TTL

8005 - 48 channel TTL

8009 - 96 channel TTL

These cards use an ASIC that emulates some of the 8255 features.