Path: utzoo!attcan!uunet!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!mips!pacbell.com!pacbell!att!mcdchg!laidbak!obdient!vpnet!cak
From: cak@vpnet.chi.il.us (Cindi Knox)
Newsgroups: comp.sys.ibm.pc
Subject: Old memory board in a new PC
Keywords: 20 mhz '386 (Zenith), old 1 meg mem. card (Zenith)
Message-ID: <267035db-1e68.1comp.sys.ibm.pc-1@vpnet.chi.il.us>
Date: 9 Jun 90 01:55:05 GMT
References: <43.266bc42c@drew.edu>
Lines: 18


Zenith reworked their extended bus specification between the 16MHz 386
and the later versions. The reason the third party board will work is
they are based on the PC-AT bus. While they will not run as fast as the
Zenith boards (running with multiple wait states and 32:16 bit conversion)
the after market boards fit the AT bus as specified by IBM and supported
by Zenith. The 32 bit boards, however, run at a different speed (note the
access time stamped on the RAMs and the delay taps on the delay lines)
and the faster Zenith computers simply ``won't wait'' for the slower RAM.
Since the old 32 bit boards were designed for 0 wait state operation, no
provision was included to drop the /READY signal to the microprocessor.
Also, I understand the pinouts have changed slightly in a nod to EISA on
the newer equipment. If you *DO* get this board to work, please let me
know. 1) I like surprises and 2) I collect wild Zenith configuration ideas.
(I was among the first to have a 10MHz ZW-241).

Cindi Knox	| You've got a lot of living to do without life.
		| 
cak@vpnet	| ``Little Miss S.'' by  Edie Brickell and New Bohemians.