Re: When to use a 74LS245 to buffer the data bus?

[Eric Smith <eric-no-spam-for-me@brouhaha.com>]

Rubywand <rubywand@swbell.net> writes:
> Usually, you would not use a bus transceiver unless there were some
> reason to isolate the peripheral bus-- like the peripheral (local)
> data bus is used by a controller on the board to talk with other chips
> on the board.

I disagree.  The Apple bus only supports two LSTTL loads per card on
most signals, and only one on some.  If your card needs to tie the
data bus or address bus to more than two chips, you should have bus
buffers, regardless of whether there's any other activity on the local
side.

Given that suitable data bus buffers (e.g., 74HCT245) are quite inexpensive,
there's very little reason NOT to use them.  If your address bus lines
go to more than one part, I'd recommend buffering them as well.