Path: utzoo!mnetor!uunet!husc6!bloom-beacon!spdcc!eli From: eli@spdcc.COM (Steve Elias) Newsgroups: comp.sys.ibm.pc Subject: progs faster at 4.77 than 10... (dma?) Message-ID: <1063@spdcc.COM> Date: 9 May 88 00:38:18 GMT References: <23988@ucbvax.BERKELEY.EDU> Reply-To: eli@spdcc.COM (Steve Elias) Organization: yes Lines: 13 the program described did lots of disk IO... disk IO on an xt always goes through the DMA controller. when your clone speed is increased from 4.77 to 10 MHz -- the clock for the DMA chip may not be increased by the 10/4.77 ratio. if the DMA clock has to be divided by some factor -- it may actually run slower at 10 mhz than 4.77. this obviously wouldn't be a great design -- it may not be your problem... a related note: the dma chip on a stock 6 Mhz AT runs slower than the chip on a 4.77 Mhz xt. the AT doesn't use DMA for disk IO, though...