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From: john@hp-pcd.UUCP (john)
Newsgroups: net.micro.pc
Subject: Re: NEC V20 How to How to USE?
Message-ID: <13600019@hpcvla.UUCP>
Date: Wed, 1-Oct-86 17:25:00 EDT
Article-I.D.: hpcvla.13600019
Posted: Wed Oct  1 17:25:00 1986
Date-Received: Sat, 4-Oct-86 10:14:28 EDT
References: <-15000@iuvax.UUCP>
Organization: Hewlett-Packard - Corvallis, OR
Lines: 23
Nf-ID: #R:iuvax:1500065:hpcvla:13600019:000:1038
Nf-From: hpcvla!john    Oct  1 13:25:00 1986

<<<<<
< Please don't blame the V20. Your problem was the speedup to 8Mhz. There are
< other chips in your pc that are sensitive to the clock rate and those need
< to be replaced as well. You must also be careful of add-on boards. Some of
< those will have problems at 8Mhz (Try running at 6Mhz, you might have better
< luck.
<                    Jeff Denenberg
<                     ..!decvax!ittvax!jeffd
< /* ---------- */
The other chip that can cause problems with the FORMAT command is the DMA
controller but replacing it with a faster one doesn't help. The problem is 
that if you increase its clock to anything greater than 6 MHZ then the
DACK pulse produced during a verify operation is to short for the floppy
controller to recognize. Read or write operations have wait states inserted
so they will still work ok but a verify operation will return DMA overrun
errors. Clones designed for 8 MHZ opertion will normally run the DMA chip
at 1/2 the CPU frequency to allow these utilities to work.




John Eaton
!hplabs!hp-pcd!john