DOS ain't dead

> The R. Loew memorial home page has a REPACKER program that can decode this
> file: https://rloewelectronics.com/distribute/REPACKER .

Thanks for the link! Here is a version which works in Linux:


#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

#define st 34
#define sz 92

void cnvt (int n, unsigned char *b1, unsigned char *b2)
{
  unsigned int i, j, l, b;
  unsigned long x1, x2;
  unsigned char k[4];
  j = n * 52;
  for (i = 0; i < j; i++)
    b1[i] = 0;
  n <<= 4;
  for (b = i = j = 0; i < n; i++, b += 26)
    {
      x1 = b2[j + 3] - st;
      x2 = b2[j + 2] - st;
      x1 = (x1 * sz) + x2;
      x2 = b2[j + 1] - st;
      x1 = (x1 * sz) + x2;
      x2 = b2[j] - st;
      x1 = (x1 * sz) + x2;
      j += 4;
      l = b & 7;
      x1 = (x1 << 6) >> l;
      k[3] = b1[b >> 3];
      k[2] = b1[(b >> 3) + 1];
      k[1] = b1[(b >> 3) + 2];
      k[0] = b1[(b >> 3) + 3];
      *(long *) (&k) |= x1;
      b1[b >> 3] = k[3];
      b1[(b >> 3) + 1] = k[2];
      b1[(b >> 3) + 2] = k[1];
      b1[(b >> 3) + 3] = k[0];
      if ((i & 15) == 15)
        j += 2;
    }
}


int main (int c, char **v)
{
  unsigned long x, y, z;
  int f1, f2, i, j, k, l;
  unsigned char b1[13 * 512], b2[(16 * 512) + 256];
  if (c < 3)
    {
      printf ("REPACKER Source Dest\n");
      return (20);
    }
  f1 = open (v[1], 0);
  if (f1 < 0)
    {
      printf ("Cannot Open Source\n");
      return (20);
    }
  f2 = creat (v[2], 0);
  if (f2 < 0)
    {
      printf ("Cannot Create Dest\n");
      return (20);
    }
lp:
  i = read (f1, b2, (16 * 512) + 256);
  if (i == 0)
    return (0);
  j = i / 66;
  l = 0;
  if (b2[(j * 66) - 2] - 13)
    {
      l = b2[(j * 66) - 2] - st;
      l -= 52;
    }
  cnvt (j, b1, b2);
  k = (j * 52) + l;
  if (write (f2, b1, k) - k)
    goto werr;
  if (l == 0)
    goto lp;
  return (0);
werr:
  printf ("Write Error\n");
  return (20);
}


The (ZIP 2.0 deflate compressed) ZIP contains this:


2019-01-01 04:13:58 ....A         2064         1476  AHCICD.SYS
2019-01-05 01:04:28 ....A         5678         2683  LICENSE.TXT
2019-01-05 01:05:56 ....A          459          178  HISTORY.TXT
2019-01-05 01:07:40 ....A         7187         2925  README.TXT


All files apart from LICENSE.TXT are identical to what can be found directly in the download mentioned earlier, without having to REPACK the "AHCICD.TXT" into the original "AHCICD.ZIP". The LICENSE.TXT contains the following:


AHCI CD/DVD DOS Driver

Copyright (C) 2018-2019
by Rudolph R. Loew
All Rights Reserved.


LICENSE AGREEMENT:

LICENSE: Rudolph Loew grants you a nonexclusive license to use the
accompanying copyrighted software program(s) (the "SOFTWARE"), which
includes any associated software components, and any online or electronic
documentation, on a single Computer, subject to the terms and restrictions
set forth in this License Agreement.

For purposes of this Agreement, a single Computer means that you are only
able to use the Software on a single Computer at a time. You may Install the
AHCI Driver on a single Computer. If you want to transfer the Software to
another Computer, you must remove the AHCI Driver from the first Computer.

You are not permitted to sell or otherwise distribute any AHCI Driver Files,

You are not permitted to lease, rent, or sublicense the SOFTWARE, use the
SOFTWARE on more Computers than allowed by your license, or in any other
unauthorized manner. Further, no license is granted to you in the human
readable code of the SOFTWARE (source code). Except as provided below, this
License Agreement does not grant you any rights to patents, copyrights,
trade secrets, trademarks, or any other rights in respect to the SOFTWARE.

By installing, running, or otherwise using the SOFTWARE, you agree to be
bound by the terms of this License Agreement.

RESTRICTIONS: Modification, reverse engineering, reverse compiling, or
disassembly of the SOFTWARE is expressly prohibited, except and only to the
extent that such activity is expressly permitted by applicable law.
Disclosure of any details of the Software is expressly prohibited.

WARNING:

THE POTENTIAL EXISTS FOR DATA LOSS OR PERMANENT LOSS TO OCCUR DUE TO ERRORS
IN THE DRIVER OR IF THE DRIVER FILES ARE BYPASSED OR OVERWRITTEN. DO NOT USE
IN CRITICAL SYSTEMS OR WHERE HUMAN SAFETY IS INVOLVED.

NO WARRANTY: THE SOFTWARE AND DOCUMENTATION ARE PROVIDED ON AN "AS IS"
BASIS AND ALL RISK IS WITH YOU. RUDOLPH LOEW MAKES NO WARRANTIES,
EXPRESS, IMPLIED OR STATUTORY, AS TO ANY MATTER WHATSOEVER. IN
PARTICULAR, ANY AND ALL WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTIES RIGHTS ARE
EXPRESSLY EXCLUDED. FURTHER, RUDOLPH LOEW MAKES NO REPRESENTATIONS OR
WARRANTIES THAT THE SOFTWARE AND DOCUMENTATION PROVIDED ARE FREE OF
ERRORS OR VIRUSES OR THAT THE SOFTWARE AND DOCUMENTATION ARE SUITABLE FOR
YOUR INTENDED USE.

LIMITATION OF LIABILITY: IN NO EVENT SHALL RUDOLPH LOEW OR HIS SUPPLIERS
BE LIABLE TO YOU OR ANY OTHER PARTY FOR ANY INCIDENTAL, SPECIAL OR
CONSEQUENTIAL DAMAGES, LOSS OF DATA OR DATA BEING RENDERED INACCURATE,
LOSS OF PROFITS OR REVENUE, OR INTERRUPTION OF BUSINESS IN ANY WAY
ARISING OUT OF OR RELATED TO THE USE OR INABILITY TO USE THE SOFTWARE
AND/OR DOCUMENTATION, REGARDLESS OF THE FORM OF ACTION, WHETHER IN
CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT PRODUCT LIABILITY OR
OTHERWISE, EVEN IF ANY REPRESENTATIVE OF RUDOLPH LOEW OR HIS SUPPLIERS
HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. THIS DISCLAIMER OF
LIABILITY FOR DAMAGES WILL NOT BE AFFECTED BY ANY FAILURE OF THE SOLE AND
EXCLUSIVE REMEDIES HEREUNDER.

EXPORT RULES: You agree that the SOFTWARE will not be shipped, transferred
or exported into any country or used in any manner prohibited by the United
States Export Administration Act or any other export laws, restrictions or
regulations (collectively the "Export Laws"). In addition, if the SOFTWARE
is identified as export controlled items under the Export Laws, you
represent and warrant that you are not a citizen, or otherwise located
within, an embargoed nation (including without limitation Iran, Iraq, Syria,
Sudan, Libya, Cuba, North Korea, and Serbia) and that you are not otherwise
prohibited under the Export Laws from receiving the SOFTWARE. All rights to
Use the SOFTWARE are granted on condition that such rights are forfeited if
you fail to comply with the terms of this Agreement.

GOVERNING LAW: This Agreement will be governed by and construed in accordance
with the laws in force of the State of New York. The respective courts of
Nassau County, New York shall have jurisdiction over all disputes relating
to this Agreement.

GENERAL PROVISIONS. If any part of this Agreement is found void and
unenforceable, it will not affect the validity of the balance of the
Agreement, which shall remain valid and enforceable according to its terms.
This Agreement shall not prejudice the statutory rights of any party dealing
as a consumer. This Agreement may only be modified by a writing signed by
Rudolph Loew. Updates may be licensed to you by Rudolph Loew with additional
or different terms. This is the entire agreement between Rudolph Loew and
you relating to the SOFTWARE and it supersedes any prior representations,
discussions, undertakings, communications or advertising relating to the
SOFTWARE.

MODIFICATIONS: Prices and Terms may change at any time. Download the current
Version of the test Program from http://rloew1.no-ip.com.

Compliance with Licenses. If you are a business or organization, you agree
that upon request from Rudolph Loew or his authorised representative, you
will within thirty (30) days fully document and certify that use of any and
all SOFTWARE at the time of the request is in conformity with your valid
licenses from Rudolph Loew.

Should you have any questions concerning this License Agreement, or if
you desire to contact Rudolph Loew for any reason, please contact
Rudolph Loew by electronic mail at: rloew thatcharacter hotmail.com.


(I have inserted "thatcharacter" instead of the at sign into the last line of the license text to keep the BTTR forum from making the email clickable and spammable)

However, remember that the rloewelectronics.com website says:


WELCOME
To the memorial homepage of
R. Loew Electronics Consulting
Rudolph Loew (Rudy) passed away on September 11th, 2019.
This site is maintained by his family to archive his work and make it available to anyone who is interested in pursuing further endeavors. You can view the original un-modified site here. Please do not try to make any purchases, all of Rudy's projects will be made available (including source code) as time permits.


The driver can also be downloaded on:

https://rloewelectronics.com/distribute/AHCICD/1.1/

It should be feasible to get some confirmation that the license no longer applies and include that in a package which can be distributed for example as part of a FreeDOS distro. Would be nice to have an open source AHCI driver with a free open source license. Maybe MIT or BSD? The disclaimer on the website sounds a bit like "public domain" but it would be nice to still remember the original author.

---
FreeDOS / DOSEMU2 / ...

> The R. Loew memorial home page has a REPACKER program that can decode this
> file: https://rloewelectronics.com/distribute/REPACKER .

I actually went through these in the hopes of finding something like that, but because this particular one has no description in the table of contents, I missed it somehow.

So this method encodes groups of 26 bits into 4 ASCII characters, where each place in the resulting ASCII string can be one out of an alphabet of 92 characters – this is what the encoder does; the decoder, which REPACKER.C constitutes, does the opposite, obviously. An alphabet size of 91 would actually be enough to cover the entire value range of 26 bits. Although nothing would be gained from using 91; the highest value used is 125 now, so there would even be room for one or two more, but 127 might be problematic, so in reality just one.

So you might call it "Base92". It is obviously slightly more efficient than the somewhat widely used "Base85" (23% size increase vs. 25%).