mitchell@cadovax.UUCP (Mitchell Lerner) (02/11/88)
O.K.
Whats the real story with extended memory on an AT running Xenix.
I was under the impression that if you got a board with anything
less than 120ns chips on it, that it wouldn't run at 10mhz.
I am finding that at 10mhz, every board that I have investigated,
inforces at least 1 wait state. If there is a wait state introduced
at 10mhz, then what would it matter if you used 150ns chips or 120ns chips?
I know that 150s cannot keep up with the bus at 10mhz, but it also
looks like 120ns chips cannot either because most of the boards
seem to employ a wait state at that speed.
Now the board that uses 150ns chips that I am talking about (the BOCA-RAM 20
AT) is garenteed(sp?) to run at 6, 8, 10, 16 and 20mhz (I guess that they
have a wait state generator that keeps adding wait states as the clock
speed goes up).
Am I really off on this one or what?
--
Mitchell Lerner
UUCP: {ucbvax,ihnp4,decvax}!trwrb!cadovax!mitchell
"When I fight with my mind, my mind always wins" - Ben Hummeltankus@hsi.UUCP (Ed Tankus) (02/15/88)
In article <1923@cadovax.UUCP>, mitchell@cadovax.UUCP (Mitchell Lerner) writes: > > O.K. > > Whats the real story with extended memory on an AT running Xenix. > > I was under the impression that if you got a board with anything > less than 120ns chips on it, that it wouldn't run at 10mhz. > > I am finding that at 10mhz, every board that I have investigated, > inforces at least 1 wait state. If there is a wait state introduced > at 10mhz, then what would it matter if you used 150ns chips or 120ns chips? > I know that 150s cannot keep up with the bus at 10mhz, but it also > looks like 120ns chips cannot either because most of the boards > seem to employ a wait state at that speed. > > Now the board that uses 150ns chips that I am talking about (the BOCA-RAM 20 > AT) is garenteed(sp?) to run at 6, 8, 10, 16 and 20mhz (I guess that they > have a wait state generator that keeps adding wait states as the clock > speed goes up). > > Am I really off on this one or what? > -- > Mitchell Lerner > UUCP: {ucbvax,ihnp4,decvax}!trwrb!cadovax!mitchell > I most times the fault can be found in the board's circuitry. Most boards were designed to support the bus speeds of the older 6/8Mhz AT's. When the machines started becoming more exotic (10-12Mhz), the boards would either require a redesign to support the faster speeds or the addition of wait states. Which do you think was the cheaper solution? (Note: this is a general explanation and not intended to cover all the bases. ET) There are some manufacturers who acutally produce zero wait state memory boards. Cheetah Int'l (1-800-CHEETAH) comes to mind. I believe these other firms may also produce these boards. Newer Technology (DART) Monolithic ? - Elephant Board (distributed by Microway) In any event, you are going to PAY for these boards because of the engineering and technology they embody. Needless to say, with the DRAM chip shortage it's only going to cost more. Cheers! -- Ed. Net : {uunet,ihnp4,noao,yale}!hsi!tankus Snail: Health Systems Int'l, 100 Broadway, New Haven, CT 06511 Bell : (203) 562-2101