On Sun, Jul 19, 2015 at 4:01 PM, N0body H0me <n0body.h...@inbox.com> wrote: > A quick search on the "Site Which Must Not Be Named" shows > some NOS 8289's for about $7 each, including postage. I dunno, > just sayin-- why re-invent the wheel?
1. The 8289, being bipolar, draws an absurd amount of current on +5V. Well over 100mA IIRC. If I were going that route, I'd want to use the 82C89, which is even harder to find and more expensive. 2. The 8289 is specifically designed for the 8086 maximum-mode bus interface, which is essentially unlike any other microprocessor's bus interface, so it will take nearly as much extra logic to convert the signals to what's needed for the 8289 as it would to just implement a suitable bus arbiter. 3. $7 is a lot to pay for something that I can implement in the FPGA for no incremental cost. 4. If I want to build more cards in five years, how much with a NOS 8289 cost then? 5. If I'm going to sell the card, which there's some chance of happening (admittedly small), I don't want to depend on availability and price of NOS parts. If there was any particular magic involved in implementing a Multibus arbiter, I'd shy away from doing it. However, it appears to actually be rather simple. The reason for my request for examples was so that I could study a few known working designs and make sure that there isn't some trick to it that I've overlooked.
