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256K 800XL Lives (Part I) [message #279953] Mon, 16 December 1985 22:08 Go to next message
bob is currently offline  bob
Messages: 108
Registered: February 2013
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Senior Member
Article-I.D.: imsvax.479
Posted: Mon Dec 16 22:08:03 1985
Date-Received: Thu, 19-Dec-85 04:24:51 EST
Organization: IMS Inc, Rockville MD
Lines: 86


   I've been working on expanding my 800XL to 256K as per the BYTE article.
I initially encountered trouble with the implementation and presumed that
the problem was in software (ATARIRAM.ASM from BYTEnet).  Much to my dismay
and eventual glee, I discovered that the shielding of the XL had grounded
the circuit causing partial operation.	With this corrected the 256K XL
expansion became operable.  Therefore, the 9/85 BYTE article "The Quarter-
Meg Atari", with supporting software, by Claus Buchholz does indeed work
as published.

   I wish to take this oppurtunity to thank all those individuals,
contributing to this net, for providing the insight and encouragement
necessary to have allowed me to continue this endeavor.

   The BYTE implementation swaps 8 32K banks by manipulating PORTB bits
4, 5, and 6.  The software provided will format a single virtual disk device
D3: or D4: as a single or double density device depending on the options
selected while assembling.  The software will format the device to a full
720 sectors.  Copying whole disks to the Ramdisk device is incredibly fast
during the Ramdisk access phases.  (I've configured a special version that
uses two single density virtual devices.  Copying between them is breath-
taking.)

   Disadvantages:  First, the 8 32K segments are not 130XE compatible.
Second, any interrupt encountered by a user program while the primary
bank (0-$7FFF) is swapped out will cause a crash.

   Short of being a great Ram-Disk application, the BYTE implementation
leaves a lot to be desired.  However, it is by no means a "dog" as it has
been referred.	If all you want is RamDisk, some inexpensive electronics
project to play around with, and desire a do-able challenge; I fully
recommend the Project as described in BYTE.  (by the way, I wield a
soldering-iron as a lumberjack would a scalpel).

   There are alternatives, however.  Some information I received from a
friend,having access to CompuServe, I am passing along in another posting.

   The first, by John P. Radigan, describes RamDisk controllers (ERAMDSK1
and ERAMDSK2) for the 9/85 BYTE circuit.  These controllers work with DOS
2.0, DOS 2.5, DOS XL, and SmartDOS (I typically use SmartDOS).	The
controllers are "object" modules that can be obtained thru CompuServe.
(Didn't I see something about BINHEX on this net, recently?)

   The second is a 130XE compatible upgrade to the original circuit by
Claus Buchholz himself.  This article modifies the original circuit to
provide complete compatibility.  The controller associated with it is
QMEGXLD.SRC.  (I do not have a copy of this code.  If anyone could obtain
it, particular Michigan netters in 517, I would appreciate a posting
either to this net or net.sources.)

   Third, the Madison Area Atari Users Group (MAAUG) has a third version
called RAMBO-XL (256K) as well as Terminator-XL (512K).  These work and have
been demonstrated according to their Newsletter.  MAAUG offers pre-printed
circuited boards (un-drilled) for a token sum.	(I've ordered 5 boards for
my User's Group and am awaiting delivery).  Anyone interested should write
(preferrably thru a User's Group) to:
    MAAUG
    P.O. Box 56191
    Madison, WI  53705

Ask for a copy of the Oct. and Nov. Newsletters ($5.00 should get some
circuit boards, I cannot speak for their production costs.)

   Fourth, fellow netter C. David Young has been kind enough to pass along
the information on his 256KXL.	He offers a hardware kit (board assembled)
for $99.95.  I've seen this in a local store.  It looks good, easy to
install, but the one I saw did not include software.  This kit seems very
complete, however, you still have to be somewhat adventuresome to summon
up the courage to dismantle your XL.  No sweat!  The kit can be purchased
from:
      CDY Consulting
      421 Hanbee
      Richardson, TX  75080
      (214) 235-2146

   Other products include: OMNIVIEW, OMNIMON, RAMROD, etc.

   The Buchholz 2nd upgrade, the MAAUG upgrade, and the CDY upgrade all use
the same address scheme to switch 12 16k banks in $4000 - $7FFF using
bits 2,3,5,6 of PORTB.	None are truly 100% compatible with the 130XE,
yet they are not really incompatible either.  They merely extend bank
switching capability beyond that defined by Atari.  All implementations are
compatible with each other, with the exception of the original BYTE
implementation.

--  Bob Burch
Re: 256K 800XL Lives (Part I) [message #279962 is a reply to message #279953] Tue, 17 December 1985 15:00 Go to previous messageGo to next message
oyster is currently offline  oyster
Messages: 11
Registered: January 1986
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Junior Member
Article-I.D.: uwmacc.1812
Posted: Tue Dec 17 15:00:01 1985
Date-Received: Fri, 20-Dec-85 01:11:37 EST
References: <479@imsvax.UUCP>
Reply-To: oyster@uwmacc.UUCP (Vicious Oyster)
Organization: UWisconsin-Madison Academic Comp Center
Lines: 36

In article <479@imsvax.UUCP> bob@imsvax.UUCP (Bob Burch) writes:
[color=blue]> [/color]
[color=blue]>    Third, the Madison Area Atari Users Group (MAAUG) has a third version[/color]
[color=blue]> called RAMBO-XL (256K) as well as Terminator-XL (512K).  These work and have[/color]
[color=blue]> been demonstrated according to their Newsletter.[/color]
[color=blue]> [/color]
   ...and according to an eyewitness (moi).  By the latest count, there are
about a dozen club members with expanded machines, evenly distributed 
between 256K and 512K.  I have the necessary parts (<$30), and am eagerly
awaiting the next hardware SIG meeting so somebody can hold my hand
through the soldering stage (I just program the darn things).
  Incidentally, the last meeting was prefaced by a bouncing ball demo--
on an 800!  It *was* a bit slower, but those buying certain nameless machines
based on that ubiquitous demo might want to consider spending $1-2K less for
the 8-bitter (:-).

[color=blue]>    The Buchholz 2nd upgrade, the MAAUG upgrade, and the CDY upgrade all use[/color]
[color=blue]> the same address scheme to switch 12 16k banks in $4000 - $7FFF using[/color]
[color=blue]> bits 2,3,5,6 of PORTB.	None are truly 100% compatible with the 130XE,[/color]
[color=blue]> yet they are not really incompatible either.  They merely extend bank[/color]
[color=blue]> switching capability beyond that defined by Atari.  All implementations are[/color]
[color=blue]> compatible with each other, with the exception of the original BYTE[/color]
[color=blue]> implementation.[/color]

   I've been meaning to post something about the updated BYTE board for the
last week.  Since you got the scoop, I'll just add the following tidbit--
Mr. Buchholz saw a copy of the MAAUG newsletter recently, and wrote a letter
to our group.  He said that he had succumbed to pressure to improve his
circuit (and sent us his result).  He noted that the two were functionally
identical, but admitted to liking ours a bit better.  He further stated
that he dislikes the "Rambo" name (I concur, though I approve of the
"Terminator" designation), and expressed his disappointment in not being
credited in the original articles (I think BYTE was mentioned, but not
Mr. Buchholz personally).  Oh well.

 - Joel ({allegra,ihnp4,seismo}!uwvax!uwmacc!oyster)
Re: 256K 800XL Lives (Part I) [message #279975 is a reply to message #279953] Wed, 18 December 1985 07:55 Go to previous message
Anonymous
Karma:
[b]Originally posted by:[/b] [email=DYOUNG@USC-ISID.ARPA (C. David Young)]DYOUNG[/email]
Article-I.D.: ucbvax.8512181303.AA23338
Posted: Wed Dec 18 07:55:12 1985
Date-Received: Fri, 20-Dec-85 05:30:35 EST
References: <479@imsvax.UUCP>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 19

Thank you Bob Burch for the informative review of the 256K upgrades
available for the 800XL. Let me just add a couple of notes:

1) I did not develop the 256KXL but am acting as a distributor for
Newell Industries.

2) The 256KXL comes with MYDOS 4.0 which does support a ramdisk in
several different configurations. Also, OMNIVIEW256 has resident
ramdisk handlers which allow you to use the ramdisk in many environments.

What a relief that all the upgrades appear to address the extra memory
in the same way! Have we stumbled upon a standard? By the way, the 256KXL
does have a switch option to replace the original function of bit 5.
With this switch you can tell ANTIC to follow banked memory or stay
in main memory when banking occurs. We needed this mod to be compatible
with TYPESETTER by XLENT Software.

David Young
-------
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