Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!jgreco
From: jgreco@csd4.milw.wisc.edu (Joe Greco)
Newsgroups: comp.sys.cbm
Subject: Re: REU Hacking.
Message-ID: <2758@csd4.milw.wisc.edu>
Date: 4 Jun 89 03:53:10 GMT
References: <2482.2487586D@isishq.FIDONET.ORG>
Sender: news@csd4.milw.wisc.edu
Reply-To: jgreco@csd4.milw.wisc.edu (Joe Greco)
Organization: Interstellar Telephone, Telegraph, and Telepath, Inc.
Lines: 47

In comp.sys.cbm article <2482.2487586D@isishq.FIDONET.ORG>, David.Johnson@f171.n221.z1.FIDONET.ORG (David Johnson) wrote:
] > Gee, my supply runs three 64's with no problems.... not
] > to mention a
] > host of other hardware.  (Turn *THAT* into a pile of ash
] >  :-)
] >
] 
]If and when it does fail (and you are courting disaster) learn from 
]someone with experience you may lose some ram chips and possibly a 
]rom/pal chip!  (I've lost 2 ram chips and my Fload cart due to a flaky 
]power supply)

If and when it does fail, it will cost me as much to replace as the
64's....  it is kind of like putting a locomotive engine in a
Volkswagen  :-)

I'm not talking about a flimsy regulated power supply, after all.  It
works, and it was more economical than buying two new bricks when two
old ones went out within a day of each other.  That's a typical
regulated supply....

] > lines revealed that the only "special" lines the REU appears
] > to use
] > are BA (Bus Available), DMA (Direct Memory Access), and
] > the I/O line
]...
]> I decided to play with DMA,...
] > Shack is closed at 2am), and everything seemed to work
] > fine.
] >
] > But it doesn't.  If you try anything "complex," it mangles
] 
]From the information provided in the 128 prog ref manual re: DMA access 
]you have to be very carefull of the state of the phase clock and access 
]the dma when the vic chip is not accessing the dma chip.  There was 
]other items re: that the dma will occur after 2 clock cycles after 
]access. "All DMA sources must yield to the vic diring phase 0 or ba 
]low.  Maybe your problem is with phase 0 as you apparently have dealt 
]with ba

That could possibly be it (there is NO info out in the 64 guide, of
course).  So, do any geniuses have a solution?
--
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