AW: AW: [OpenBIOS] OT: Bios access speeds

[Matthias Wächter]

On Fri, 30 Apr 1999, Qiwei Xiao wrote:

> > > Sorry, the 74HC245 is no address decoder, it's an 8 bit parallel buffer
> > > driver (usually used for the data bus).
> > Hm, what else is used? I can only see this 74245 everywhere... :)
> Address decoders are 74LS138 (3 to 8) and 74LS139 (dual 2 to 4). I can 
> remember almost all the chips in 74 series. Newer motherboards usually 
> don't use them (build the functions in LSI/VLSI/FPGA). 

The Problem with the '138 is, that it just decodes 3 address lines where
one needs much more, but outputs 8 where one typically needs 1 or 2. So I
think, a GAL is better suited, additionally because it's reprogrammable.

> Qiwei

Sehr Wus,
- Matthias

-- 
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