dhoelzer@csserv2.ic.sunysb.edu (David S Hoelzer) (02/28/91)
I'm looking for someone with information about the original 6 MHz AT Memory. Now on the XT's, there was a way to upgrade the board to 640.. I'm looking for someone with info on the same thing for the 512k AT motherboard. This is the full-sized baby... I'd appreciate any responses.. ------------------------------------------------------------------------------- dhoelzer@csserv1.ic.sunysb.edu | If we shadows have offended, Think but this paladin!dhoelzer@uunet.uu.net | and all is mended, That you have but slum- dhoelzer@mole.ai.mit.edu | bered here Whilst these shadows did appear. -------------------------------------------------------------------------------
henry@garp.mit.edu (Henry Mensch) (03/05/91)
dhoelzer@csserv2.ic.sunysb.edu (David S Hoelzer) writes: |> I'm looking for someone with information about the original 6 MHz AT |> Memory. Now on the XT's, there was a way to upgrade the board to 640.. I'm |> looking for someone with info on the same thing for the 512k AT motherboard. |> This is the full-sized baby... me too! i need a 128k memory expansion for a PC/AT, and these seem to be (rightfully) a scarce item these days ... while my original AT has 1Mb in it, only 512k is visible to DOS (the other 512k is extended <??> memory, used as a ram diskette :>). any clues would be welcome. -- # Henry Mensch / <henry@garp.mit.edu> / E40-379 MIT, Cambridge, MA # <hmensch@uk.ac.nsfnet-relay> / <henry@tts.lth.se> / <mensch@munnari.oz.au> # via X.400: S=mensch; OU=informatik; P=tu-muenchen; A=dbp; C=de
thoger@solan.unit.no (Terje Th|gersen) (03/06/91)
In article <5422@media-lab.MEDIA.MIT.EDU> henry@garp.mit.edu (Henry Mensch) writes: dhoelzer@csserv2.ic.sunysb.edu (David S Hoelzer) writes: |> I'm looking for someone with information about the original 6 MHz AT |> Memory. Now on the XT's, there was a way to upgrade the board to 640.. I'm |> looking for someone with info on the same thing for the 512k AT motherboard. |> This is the full-sized baby... me too! i need a 128k memory expansion for a PC/AT, and these seem to be (rightfully) a scarce item these days ... while my original AT has 1Mb in it, only 512k is visible to DOS (the other 512k is extended <??> memory, used as a ram diskette :>). any clues would be welcome. BocaRAM sells a card called the TophAT, which is a drop-in 128K memory expansion for 512K AT's. I don't remember the price exactly, but it wasn't too bad.. If memory serves me right, the original AT used some 128 kilobit piggy-backed memorychips that might be hard to come by today. (I think it was something like two 64 kilobit chips soldered together. Anybody out there have some sure knowledge on this ??) On the other hand, an EMS 4.0 card can usually be set up to backfill memory up tp 640K, giving you the effect you want and EMS memory as a bonus. These cards run about USD 100-120 unpopulated. Beware, though if you intend to keep these cards when upgrading to a 386, that some of them fail at higher processor- or bus-speeds. Two cards known to flunk this test are the BocaRAM AT (not the Plus), and an AST Premium Advantage. Also, some of the older boards do not do EMS 4.0 in hardware, but only emulate it with software. These boards cannot be used for multitasking under DesqView/Windows-286. (The BocaRAM AT fails this test, too.) -Terje -- ____________________________________________________________________________ thoger@solan.unit.no | Institute of Physical Chemistry THOGER AT NORUNIT.BITNET | Div. of Computer Assisted Instrumental Analysis | Norwegian Institute of Technology
angelini@apollo.HP.COM (Bob Angelini) (03/07/91)
|> I'm looking for someone with information about the original 6 MHz AT |> Memory. Now on the XT's, there was a way to upgrade the board to 640.. I'm |> looking for someone with info on the same thing for the 512k AT motherboard. |> This is the full-sized baby... The original AT's use piggy-backed 128Kbit drams modules (for 256K bit/module). These chips are not pin compatable with standard 256K bit drams. The easyist way to upgrade either a 256K or 512K AT is with any noumer of 3rd party memmory boards. I use an AST Advantage board, and others here use the AST Rampage board. Bob Angelini angelini@apollo.hp.com
phil@cs.mcgill.ca (Philip LOCONG) (03/08/91)
Many people mention the piggy back chips and say it's better to use an expansion card. I don't think there is a choice, the 6Mhz ATs have room for 512k on the MB (well, mine does) and you have to fill it up, otherwise, you can't backfill. Then you can use an expansion card to get 640k. Let's start a long technical thread !
amichiel@rodan.acs.syr.edu (Allen J Michielsen) (03/10/91)
In article <5038bdcd.20b6d> angelini@apollo.HP.COM (Bob Angelini) writes: >|> I'm looking for someone with information about the original 6 MHz AT >|> Memory. Now on the XT's, there was a way to upgrade the board to 640.. Sorry, this is true only of the 256-640 system board. This would have been the last production run, and only accounted for a very small (1%) of the ibm xt population. I have only seen one of these out the several hundred ibm's I've cracked open. >|> looking for someone with info on the same thing for the 512k AT motherb >|> This is the full-sized baby... >The original AT's use piggy-backed 128Kbit drams modules >(for 256K bit/module). These chips are not pin compatable with standard 256K >bit drams. The easyist way to upgrade either a 256K or 512K AT is with any >... 3rd party memmory boards. 1. Did IBM ever make a 'baby AT', I've only seen 'the full-sized baby'. 2. Did IBM ever make a 256K AT motherboard, I've only seen 512K motherboards of which 256K probably could have been a standard config. 3. The motherboard has 4 banks of sockets, so if they were piggy-backed 128K chips for 256K bit/module, this would be 1 MB on the motherboard (yes the 286 is 16 bit, but there are 2 extra parity chips then, or the measurement is still 8 bit words, or the documentation itself calls it 512, logically then, theses are piggy backed 64K drams forming 128K drams. It is possible to reverse 'engineer' these 128K drams from 64K drams by jumping pins, but the resulting kludge is too big to fit under many cards. 4. IBM made a 512K to 640K memory expansion card I have seen several adds for available today, used. It used the same chips, and the chips are also available used today. The cost of either of these makes it more cost effective to use a 3rd party board. 5. MANY 3rd party boards do NOT allow addressing back into the 512k to 640K region. The feature is called back filling or split (range) addressing generally. I'd say that MOST 'NAME BRAND' (intel/inboard/inboard plus, or ast for example) will provide this feature. However, thie will result in a amount of extended/expanded memory that is a 'odd' amount. Given the cost of addin boards, and the resulting performance gains from 512 to 640K, I believe that you may be better off letting the addin board provide more extended/expanded memory and NOT ffilling the 512 to 640 region. That is of course, if you don;t have a application that requires more base memory... al -- Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University InterNet: amichiel@rodan.acs.syr.edu amichiel@sunrise.acs.syr.edu Bitnet: AMICHIEL@SUNRISE