Path: utzoo!attcan!uunet!husc6!purdue!decwrl!nac.dec.com!plouff
From: plouff@nac.dec.com (Wes Plouff)
Newsgroups: comp.sys.amiga
Subject: Comments and Questions on Lucas
Message-ID: <8811110336.AA17455@decwrl.dec.com>
Date: 11 Nov 88 06:26:00 GMT
Organization: Digital Equipment Corporation
Lines: 50

[The first posting of this message got caught in mail-virus madness, so 
here it is again.]

First, hats off to Brad Fowles!  It's not ugly at all.  Cheap, yes, 
ugly, no.  The DSACK tuning seems a minor weakness in an excellent 
effort.  Herewith a few short comments...

- Brad recommends storing the unused 68000 chip in styrofoam.  That's a 
real static electricity no-no.  Use conductive foam, black and crumbly 
or pink and bubbly.  Even though 68000s cost only $12 or so, this is a 
dumb way to lose one.

- In urging Commodore to produce a "68030 for Amiga 2000," Chris Gray
(myrias!cg) says:
 
>We hear stories on the net that Commodore has a 33 MHz 68030 card for the
>Amiga 2000 running.  

>Is something along this lines the reason why they haven't released the
>   68020 card yet? After all, it's 14 MHz doesn't seem like a lot, especially
>   now that there is a public domain one (LUCAS) that's faster than that for
>   considerably less money.

Higher clock speed is not the only way to get performance.  Faster memory 
and 32-bit memory each add significant performance to a 68020 system.  
When the memory "granddaughter" card is available, then make a 
comparison.  Until then, I'd bet on the Commodore card. Hal
Hardenbaugh's columns in _Programmer's Journal_ and elsewhere have
explained this memory bandwidth problem. 

- Dave Haynie (who certainly ought to know about 68020s) calls Lucas a 
"hack."  Well, compared to some A1000 products out there, Lucas is 
pretty good.  As a hardware engineer, I cringe at the design where DSACK 
timing depends on choosing U9, rather than on worst case timing.  But 
that seems a minor sin compared to the flaky bus timing of many SOTS boxes.

Now the questions...

- How should the jumpers (next to U4 on the schematic) be connected?

- With superfast RAM installed through the DIN connector, how will short 
memory cycles (about 2 clocks on the Amiga bus) affect the regular Amiga 
timing circuits, especially the Chip RAM multiplexing?

-- 
Wes Plouff, Digital Equipment Corp, Littleton, Mass.
plouff%nac.dec@decwrl.dec.com

"All the popular bugs in the RAM-Handler were fixed in Version 1.3."
			  Amiga Enhancer Software Manual, page 1-17