pat@orac.pgh.pa.us (Pat Barron) (12/20/88)
Is it possible to put more than one combo card in a 7300? If so, can they both have memory on them (for instance, one 1.5M combo card, and one 0.5M card)? Can you use more than one combo card if only one has memory? I should probably know all this stuff from the docs for the combo card. Unfortunately, I got my card without any documentation of any kind... Thanks, --Pat. -- Pat Barron Internet: pat@orac.pgh.pa.us - or - orac!pat@gateway.sei.cmu.edu UUCP: ...!uunet!apexepa!sei!orac!pat - or - ...!pitt!darth!orac!pat
jcm@mtunb.ATT.COM (was-John McMillan) (12/22/88)
> Is it possible to put more than one combo card in a 7300? Yes. It's frequently done. > If so, can they both have memory on them Yes. But not for any good reason :-) [A 1.0M and .5M card might work.] > (for instance, one 1.5M combo card, and one 0.5M card)? No. [See below.] > Can you use more than one combo card if only one has memory? Yes. It's frequently done. > I should probably know all this stuff from the docs... (I would hope they're of some use...) > Unfortunately, I got my card without any documentation... And, you tuned into the news columns a week too late. To reprise: There are 2 (logical) banks of RAM on the card: - a .5 MB bank - a 1 MB bank (containing 2 physical banks of RAM) ...A 1.5 MB card uses BOTH logical banks. Each bank is at a FIXED address (and is assigned fixed physical banks on the card). ...Ergo, you CANNOT use 1.5 MB on one card and .5 MB on another -- the .5MB component of each would occupy the same address space. ...Ergo, when one migrates from .5 to 1 MB, you must de-populate the one physical bank, only to re-insert the chips in an adjacent bank. There is a 2 MB RAM card available: it is the only trivial solution I've seen to getting 2 MB expansion-bus memory. (The past two weeks of news items have discussed clever, masochistic modifications to get 2 MB ;^} ) Do you need 2 MB on the expansion bus? I've used 7300/3B1's intensely for 3.8 years, compiling, StarLAN'ing, and providing troff/PostScript(R) services. I wouldn't expect noticeable improvements migrating from 3.5 to 4 MB (total), and wouldn't expect much in migrating from 2.5 MB to 3 MB. Yes Virginia, there are exceptions. Disks are typically the principle factor in sustaining high throughput. RAM serves to either diminish paging activity or increase disk-cache "hits". For the 3B1, a cache limit of around 120 is absolute because of the design-constrained 1.5 MB limit on kernel virtual address space -- more specifically, the .5 MB limit on core-kernel + tunable arrays. Below 2 MB RAM (total) things deteriorate, and below 1.5 MB one can plummet into page thrashing with large codes. (Try large compilations with .5 RAM for fun :v) If you're having problems with throughput, maybe a disk upgrade will be in your generic seasonal stocking. Seasoned greetings, and all that. - - - - - - John McMillan -- att!mtunb!jcm ... speaking only for himself, if that.
mvadh@cbnews.ATT.COM (andrew.d.hay) (12/22/88)
In article <166@orac.pgh.pa.us> pat@orac.pgh.pa.us (Pat Barron) writes:
-->
-->Is it possible to put more than one combo card in a 7300? If so,
-->can they both have memory on them (for instance, one 1.5M combo
-->card, and one 0.5M card)? Can you use more than one combo card if
-->only one has memory?
-->
someone posted recently that if one card is in slot 3,
2 cards may each have 1Mb.
i don't know if it's true, but i do know that the ports are mapped
uniquely -- i've actually had 6 in one machine.mvadh@cbnews.ATT.COM (andrew.d.hay) (12/22/88)
In article <166@orac.pgh.pa.us> pat@orac.pgh.pa.us (Pat Barron) writes:
-->
-->Is it possible to put more than one combo card in a 7300? If so,
-->can they both have memory on them (for instance, one 1.5M combo
-->card, and one 0.5M card)? Can you use more than one combo card if
-->only one has memory?
-->
someone posted recently that if one card is in slot 3,
2 cards may each have 1Mb.
i don't know if it's true, but i do know that the ports are mapped
uniquely -- i've actually had 6 in one machine!
--
Andrew Hay +------------------------------------------------------+
Holistic Specialist | I will design a computer for you, so powerful that |
AT&T-BL Ward Hill MA | organic life will form part of its operational matrix|
mvuxq.att.com!adh +------------------------------------------------------+