Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uflorida!haven!mimsy!mojo!disney!josip From: josip@ra.src.umd.edu (Josip Loncaric) Newsgroups: sci.electronics Subject: Re: Advice needed on wire-wrapping CPU based circuits Keywords: wire-wrap advice needed Message-ID: <1990Sep3.162445.21387@ra.src.umd.edu> Date: 3 Sep 90 16:24:45 GMT References: <409@horizon.COM> <3344@stl.stc.co.uk> Sender: news@ra.src.umd.edu (The News System) Organization: Systems Research Center, University of Maryland, College Park Lines: 25 In article <3344@stl.stc.co.uk> grc@larch.UUCP (Gary Cook) writes: >In article <409@horizon.COM> kevin@horizon.COM (Kevin Criqui) writes: >> >>I'm in the process of prototyping a small computer with a MC68000, some >>EPROM, a duart and (hopefully), 8 megs of DRAM. I've wire-wrapped the >>circuit on a piece of perf board. In trying to get the DRAM controller ... One thing I've been told in the past is that you should be careful and avoid wrapping the insulated portion of the wire around the pin. This precaution is important, because otherwise you are essentially creating small inductors at each end of your wire. Another "rule-of-thumb" for high-frequency circuits is that point-to-point wireing works better (less crosstalk etc.) than neat wireing jobs. Labs I've worked in have had no wirewrapping related problems with fairly simple circuits operating at up to 20MHz, and presumably the "rules" mentioned above deserve some credit. -- Josip Loncaric / SRC / U. of Maryland / -------------------------------------------------------------- ! Today's Special: Opinions....$0.02 each ! --------------------------------------------------------------