Connecting Teensy 4.1 to PC 8 bit ISA bus

[zb10948]

Hello,

I want to use Teensy 4.1 as a "main driver" for 8 bit ISA expansion card project.
I was wondering has anyone been doing anything similar and can I get recommendations for appropriate buffer ICs for digital I/O interface?

Thanks in advance

 

[jmarsh]

Need a bit more info for a full answer - will it be using the data bus bidirectionally or only one direction? Can the address decoding be handled (either in full or at least partly) with logic or do all the address pins need to be connected to the Teensy?

 

[zb10948]

Hi jmarsh thanks for the reply.
The data bus will be used in both directions. If it's possible to get all the address lines to Teensy that would be a better option than latching onto a particular address because the card could have several functions. I need some pins left for the VGA out feature, right now I'm using analogue out with 10 pins used but in the end I want it to be digital out and that may use even more.

Below I've attached the image from Scott Baker's Raspberry Pi to ISA design. He latches a dualport memory buffer on the bus side, and puts a FET bus switch on the GPIO side, so 3 ICs.

Am I right to assume Teensy can do without memory buffer? Unlike RPi running Phyton this is realtime on internal memory.

Thanks,
Z