Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!mailrus!ames!oliveb!amiga!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: 68020/68881 board
Message-ID: <4480@cbmvax.UUCP>
Date: 11 Aug 88 19:19:08 GMT
References: <11655@cisunx.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 44

in article <11655@cisunx.UUCP>, ejkst@cisunx.UUCP (Eric J. Kennedy) says:

> In article <4447@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:
>>> 1) How compatible is it with current software?

>>Very, like probably 99.9%.  What's likely to die?  Only thing that occurs to me
>>is the R-C type dongle, as used with X-CAD.  These things are very sensitive
>>to CPU speed, generally depending on CPU dependent timing loops.  Under V1.3,
>>the 68881 interface will be supported if they did it right.

> If my Superbase Professional dongle dies, (same company)  I'm going to 
> be SCREAMING mad!!  

Actually, isn't X-CAD from the folks who make Aquisition?  I know both are
British companies, but I didn't think they were the same.

The Dongle Snooper I use tells me that the SuperBase Professional dongle I
have here is of the resistor-on-a-pot-line variety (13k-16k).  Providing that's
correct, this dongle should be immune to CPU speed variations.  The X-CAD
dongle we tried here was identified as the R-C constant varitey.  That's
real bad news, and it didn't surprise me that the darn thing failed.  The
theory behind is that a capacitor is charged and discharged under program
control, with one input line to sense the capacitor's charge.  While that's
a purely digital sensing, what they do is start a timer and read that port
line until a "1" is sensed.  Same thing can be done with a discharge of the
cap.  The problem is that, unless the programmer was smart enough to use a
timer, the count produced is just going to be a CPU based count, and that's
100% dependent on CPU speed.  

And I should mention that Commodore-Amiga definitely doesn't support this
kind of dongle, since Commodore-Amiga doesn't support anything that's
dependent on a fixed CPU speed.

> Damn ##$$@^%$! dongles

I'll agree with that in any case.

> ------------
> Eric Kennedy
> ejkst@cisunx.UUCP
-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {ihnp4|uunet|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
		"I can't relax, 'cause I'm a Boinger!"