Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!cs.utexas.edu!sm.unisys.com!hplabs!hp-pcd!hplsla!hpvcla!johne
From: johne@hpvcla.HP.COM (John Eaton)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Info. needed about DMA controllers
Message-ID: <4740025@hpvcla.HP.COM>
Date: 14 Oct 88 15:59:49 GMT
References: <1398@percival.UUCP>
Organization: Hewlett Packard, Vancouver, WA
Lines: 16

<<<<
< I have been unable to locate an 8237A-2 (8MHz). Most data books
< (AMD, INTEL, NEC, etc.) indicate that the 8237A-5 is the fastest
< version made. 
----------
Harris makes a CMOS 82C37A that runs up to 8 Mhz. It was listed in their
1986 data book. I would check the clock pin of the chip before investing
any money since it may not be operated at 8 mhz in your machine. They 
might run the DMA at 4.77Mhz normal and 4Mhz turbo in order to keep the
chip within specs. If you run a 8237 above 6Mhz then the pulse width of
the DACK* signal in verify mode is to short for a standard 765 Floppy
controller. 


John Eaton
!hpvcla!johne