I'd like to get VHDL libraries for 74xx generic logic chips. I know
breadboard design with these chips, and looking at the HDL description
would help me learn
FMF keeps on reporting "page not found" when I try to check out their
models.
Hi,
you want to start hardware design with VHDL now, after your experience
with 74xx chips.
Well, that's quite OK, since many of the people here have gone that
way. (mee too)
But let me give you one hint.
Forget most of the things you have done with the 74xx stuff.
Even HDL descriptions of these chips are not really good for learning.
The reason is, that
1) these chips sometimes have a weird structure compared to actual
synchronous design techniques.
2) the descriptions are mostly meant for system simulation purposes,
they are not always synthesizable.
Depending on what new technology you are targeting (CPLD, FPGA, (std.
cell)ASIC) you should work it out the way you did with the old chips
too:
Read the datasheet.
Try to understand the features and quirks of that technology.
Then you are able to design something good.
Just some examples:
From 74xx you are used to having the gate delays in mind. Nowadays the
wires introduce sometimes even higher delays than the gates.
74xx series used a lot of JK-FFs to save logic. That's just not needed
anymore since you are mostly limited to D-FFs (except in asics) and
the synthesis tool will choose the optimal logic-ff combination
anyway.
VHDL in the end is just some way to describe circuits in text form and
you better look at good and useful examples. e.g. here:
"RTL Hardware Design using VHDL" by Pong P. Chu
Have a nice synthesis
Eilert