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Last edit: 05-03-17 Graham Wideman


Software and Hardware Projects and Products
ISA Interface Cards and Lab Instrumentation Buses
Article created: 98-06-01
Name/Date Description, Pics
PC ISA I/O cards, instrumentation/ control buses, 1982-90 Many of the projects I have been involved with required interfaces to PCs. When commercial cards couldn't be found to fill the need, we developed our own.  Along with numerous one-of-a-kind units, we developed a couple of generations of general-purpose interface cards with external control buses to talk to remote data-collection modules.

World's Greatest*
ISA Parallel
Interface card

* your opinon may vary

 io96_bd.gif (33055 bytes)Ever used a PC parallel interface card? If there's anything that should be simplicity itself, but isn't, that is it. Almost all commercial units are just ISA-interfaced 8255s, suffering from idiosyncratic modes, inconsistent capabilities on each I/O and wimpy drive that varies from one pin to another. Eventually I got so impatient that I designed...

IO96: A decent parallel interface card.   96-lines of HCT high drive output or high-impedance input  -- sufficient for driving opto-couplers, for example.  Six identical sections, each based on a pair of 74HCT652's.  Under software control, each byte can be in or out, latched or unlatched. And no funky 8255 PIO programming, or "some bits can do this and some can't" confusion.

I/O driver


io96_io.gif (25662 bytes)Guess what, we often used IO96 in...  lab instrumentation!  This pic shows one each of opto-isolated 16-line input and output terminal cards. (Indicator LEDs are on the reverse side.)

One entertaining non-lab project that got an IO96 was a PC-controlled on-set display used for several years on the San Diego Easter Seals Telethon TV show.  The display was a large "Circle of Lights" bar graph that gave a real-time indicator of the level of phone-in response. (If I ever go into mail-order again....)

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