Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!decwrl!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!frohne
From: frohne@pur-ee.UUCP (Henry R Frohne)
Newsgroups: comp.sys.amiga
Subject: Re: Have you had a lot of bad floppies lately with your A500?  The answer!
Message-ID: <8090@pur-ee.UUCP>
Date: 10 May 88 16:13:21 GMT
References: <8805100305.AA09860@cory.Berkeley.EDU>
Organization: Purdue University Engineering Computer Network
Lines: 34
Summary: Home made drive details...

In article <8805100305.AA09860@cory.Berkeley.EDU>, dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
> :	A500 with .5M extra memory (A501 look alike), one extra 3.5"
> :	floppy (not the A1010) which is an IBM floppy made to run on
> :	the Amiga using a couple of 74LS chips as has been discussed
> :	on the net, and a standard A500 power supply.
> :
> 	Sounds like either you forgot some bypass capacitors on the LS TTL
> or you were overloading the poor A500 power supply with the combination
> LS TTL and foreign disk.  

I have include bypass capacitors on all the 74LS chips (a 74LS38 and 74LS74) 
The floppy is a Toshiba FDD4206A0K.  It may draw more current than the A1010.

>Have you checked the amount of power the 

The voltage drop across the drive was a couple of tenths of a volt when in
use on the 5 volt line and something similar on the 12 volt line.

> floppy + support LS TTL is pulling?  An IBM 150 watt power supply could
> certainly (appear to) fix both problems.  Where are you pulling the 5V for
> the LS TTL from?  

I am taking the power from the DB-23 connector on the amiga.

>How many chips and of what type are they?  Are they *all* 
> LS?  

(Answered above.)

By the way Matt, thanks for all the nice software you have shared with
the Amiga community!


						Rob Frohne
						pur-ee!frohne