intel IO chips in a 68000 board ?
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Author:  Span [ Tue Jun 05, 2018 4:37 pm ]
Post subject:  intel IO chips in a 68000 board ?

Hi again,
Still fiddling with my 68000 Just in the process of putting together another prototype board and want a pio chip for parallel io ( Disk maybe ) and some counter timers
I dont have any 68230 chips but i do have a bunch of intel 8255's and a couple of 8254's I have had a quick look on the net and seen people using the 8255 chip
for all sorts of things, but have not seen the 8254 counter/timer chip used anywhere, I have a couple of them and they are thought to be good 3 counter timers with
clk/gate/output brought out. DC to 10mhz clk rate, My initial thoughts were just hang it on the bus and tie one of the output pins to an interrupt line.
Have i missed any fundamental reason not to use these chips with the 68000 ? The data sheet says compatible with all Intel and most other Microprocessors.
Also of course if i bugger them they seem to be easier to get than the Motorola chips.

Author:  Plasmo [ Wed Jun 06, 2018 5:14 pm ]
Post subject:  Re: intel IO chips in a 68000 board ?

I have not done 8254 interface with 68000, but looking at the datasheet, I don't see why there should be any issues. You have to generate DTACK for 68000 and watch out for the differences in nCS and nWR/nRD timing, but that's generic interfacing circuits between Motorola & Intel products.

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