Path: utzoo!utgpu!news-server.csri.toronto.edu!qucdn!leek
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 68030 in a LUCAS board, and 2.0 in FRANCES
Organization: Queen's University at Kingston
Date: Tuesday, 4 Sep 1990 20:56:00 EDT
From: <LEEK@QUCDN.QueensU.CA>
Message-ID: <90247.205600LEEK@QUCDN.BITNET>
References: <144.26d7d916@intersil.uucp> <14194@cbmvax.commodore.com>

In article <14194@cbmvax.commodore.com>, daveh@cbmvax.commodore.com (Dave
Haynie) says:
>
>>So it appears one of two things must be happening:  The FRANCES data buffers
>>are being enabled during reads of non-FRANCES data (yikes!), or the FRANCES
>>memory is not cacheable, but I have no idea why this would be.  Nothing is
>>reading or writing to FRANCES except the 030.
>
>The problem is very likely that your FRANCES memory isn't cachable.  In order
>to be considered data cachable by the '030, your memory board must always
>read its full port width, regardless of SIZ1-0 or A1-0.  Simply put, all four
>bytes of your 32 bit memory must be valid for reads, or it won't be cachable.
>Most 68020 memory designs use the same byte enable logic for reads as writes,
>and therein lies the problem.

Yeap.  Memory banks are enabled with A0, A1, Siz0, Siz1.  Seem to me the fix
is to have a new Frances PAL.  We can use the AMY (pin 11) for R/*W20 and
have !CS-AMY at pin 16 (Currently *CS) and !CS-NAMY at Pin 19 (currently unused
).  !CS-AMY is just !CS hardwired for amy space while !CS-NAMY is hardwired
for outside amy space.

!CS-AMY = !MA23 & MA22 & !A31 & !A30
!CS-NAMY = !MA23 & MA22 & !A31 & A30

One can always cut a trace and solder a jumper to use *CS-NAMY putting
Frances outside the lower 16M space.  Still need to work out the !UUD, !UMD,
!LMD, !LLD for selecting memory banks...

How's that for minimize changes in Frances circuit board ?  Hope you can get
the 030 to cache Frances...  Can't wait to get a 030 in my Lucas/Frances...

Fun thing to do is to separate the 881/882 clock from 020 clock - need
to do that before soldering in the socket.

>
>>Fred Hamilton                  Any views, comments, or ideas expressed here
>>Harris Semiconductor           are entirely my own.  Even good ones.
>

Hope you get this to work... Get ready for a 040.  @B^)


>--
>Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
>   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
>      Get that coffee outta my face, put a Margarita in its place!

Thanks !!  That's probably the problem.

K. C. Lee
Elec. Eng. Grad. Student