djw@hpldsla.HP.COM (03/21/90)
A friend of mine just added a 2 meg bank of 1megx1bit 80ns DRAM to his 80286, NEAT chip set clone. The computer already had a 1/2 meg bank of 256kx1bit 120ns DRAM. He configured the memory controller (is that right??) for 120ns memory. So, all should work fine, and he should get 2.5 megs with a speed of 120ns - right? Wrong, it just hangs, and won't boot. What's the problem here? Is it something to do with the refresh times? That is, maybe the 80ns drams need to be refreshed faster than 120ns setting will do? He's just going to continue with 2 megs for now, but this is puzzling, and it would be nice to use the other 1/2 meg (the extra speed is not as important). thanks for your advice, David Williams ___________________________________________________________________ Hewlett-Packard Scientific Instruments Division (SID) /\___________ 1601 California Ave, Palo Alto, CA, USA. /\______________/\________ phone: 415 857 6100. FAX: 415 852 8011 //\\____________|__________ HP-UX Mail: djw@hpldsla.hp.com / \____/\____/\___________ HPdesk: (djw)hpldsla/HP1900/00 /\____________/ \__________
dhinds@portia.Stanford.EDU (David Hinds) (03/22/90)
In article <2340003@hpldsla.HP.COM>, djw@hpldsla.HP.COM writes: > A friend of mine just added a 2 meg bank of 1megx1bit 80ns DRAM > to his 80286, NEAT chip set clone. The computer already had a > 1/2 meg bank of 256kx1bit 120ns DRAM. > > He configured the memory controller (is that right??) for 120ns > memory. > > So, all should work fine, and he should get 2.5 megs with a > speed of 120ns - right? > The problem may be that the chip set cannot handle mixing two bank sizes. My chip set is different, but I know that it will only allow either all 256K-wide or all 1M-wide memory modules. In general, I think DRAM's with different speeds are like CPU's with different speeds - a faster DRAM simply passed a more stringent quality control test. I think this applies to 80ns vs 120ns chips, **where the chip design is the same**. However, 256K chips may have different refresh requirements from 1M chips, even at the SAME speed. I don't know whether this is true or not. -David Hinds dhinds@popserver.stanford.edu
phil@pepsi.amd.com (Phil Ngai) (03/24/90)
In article <2340003@hpldsla.HP.COM> djw@hpldsla.HP.COM writes: |A friend of mine just added a 2 meg bank of 1megx1bit 80ns DRAM |to his 80286, NEAT chip set clone. The computer already had a |1/2 meg bank of 256kx1bit 120ns DRAM. From what I can tell, the so-called NEAT chip set can not handle this. You need 36 chips of one kind before you can put in a different kind. This is due to their bank interleave "feature". -- Phil Ngai, phil@amd.com {uunet,decwrl,ucbvax}!amdcad!phil Boycott the census! With the history of abuse census data has, can you afford to trust the government?