Tony Duell wrote:
> For experimental and educational projects I much prefer TTL (including,
> of course the CMOS versions of the TTL chips, like 74HCxxx parts). It's
> easier to prototype with, easier to test (you can clip the 'scope or
> logic analyser wherever you like), and easier to see what's really going
> on. It's quicker to make small changes to the circuit as well (on an FPGA
> design I did about 5 years ago, a full compile of the main chip took
> overnigh (OK, PCs have got faster since then, but FPGAs have also got
> larger!)). That meant every small change took a day to test. A soldering
> iron and/or wire-wrap tool is a lot faster for changing a few connections
> :-) You also aren't tied to a proprietry program running on some
> computer/OS that I don't have...
Until I got over 95% of logic filled in my Altera FPGA, most compiles
were under 15 minutes.( BTW -- Since I have 100% of the FPGA used it is
time to stop upgrading the design :)). I live in the middle of (looks
around) snow thus getting stuff mail order is the only way to get parts
often from the USA but some even from Australia.
> Please don't attempt to convince me that FPGAs make more sense for
> production. I don't need convincing of that...
TTL is still better for production. (grin).
> I wouldn't call those SSI parts.
Ok SSI and MSI parts. Compared to millions of transistors in a cpu, all
TTL parts are small. BTW altera has a fairly nice macro library for
their FPGA's.
> Why? The '181 has many more operations, some of them useful....
I want A+~B,~A+B,A+B,A^B,A|B,A*B alu functions. The 181 can't give me
that.
> Sure... I guess 74x170s are really hard to find now :-(.. All these
> wonderful chips I grew up using are discontinued :-(
More like a 74xx00. The Tiny chips are sure popular today, who would of
thought single gate chips would sell.
--
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html
Received on Tue Apr 09 2002 - 22:38:05 BST