Updated 20190215

What happened to PC99?

The last versions of PC99 were PC99 Stage 6 Full and PC99 Stage 6 Light. PC99 Stage 6 Full is now called PC99 DOS. PC99 Stage 6 Light is discontinued and is no longer a supported product.

PC99 DOS is included with CaDD PC99 Suite. It requires DOSBox to run on Windows 7 and higher. There are some changes to cfg.exe to integrate PC99 DOS into the Suite environment.

For full information see: “PC99 DOS”

What happens to my copy of The Cyc?

If you own The Cyc, you are a registered owner of either PC99 Stage 6 Full or PC99 Stage 6 Light.

CaDD PC99 Suite contains a full copy of The Cyc and is almost certainly later than the version you have. When you have installed CaDD PC99 Suite, The Cyc can be found in \cadd\cyc. You are requested to destroy your current copy of The Cyc. The license you have does not allow The Cyc to be resold. The Suite version has many new files, and updated files. Under no circumstances should you try to mix and match versions of The Cyc as this will break hyperlinks to any files that have been moved or renamed. Just rest assured that the Suite version of The Cyc is complete.

If you have no interest in CaDD PC99 Suite, but just want the latest copy of The Cyc, you can still order an update as before. The cost is $15.94 in the US, and $21.94 overseas. The price includes shipping and handling. Because The Cyc is now integrated in CaDD PC99 Suite, it will need to be “unbundled” for an upgrade, i.e., there will be no Suite files on the DVD. Please allow an extra three days for this process after CaDD receives your order.

What do I do with the optional TI 5.25″ disk if ordered?

Optionally included with CaDD PC99 Suite is a TI 5.25″ DSSD disk. This disk contains the CaDD PC99 Suite transfer utilities written in TMS9900 Assembly Language that allow you to¬† transfer binary images of TI disks between a TI-99/4A and a PC that are cabled together through the TI RS232 and PC COM or USB->COM ports. The cable is an off-the-shelf AT modem cable — not a null modem cable — for a PC COM port. [See the PC99 DOS documentation for pinouts.]

After installation of CaDD PC99 Suite, A binary image of the CaDD TI 5.25″ disk is stored in \cadd\dsk\pc99.dsk. It is a Windows file.

To transfer disks you run a 9900 Assembly Language program on the TI, which is loaded from the CaDD 5.25″ disk. You run the companion 9900 Assembly Language program on the PC, and it is loaded from pc99.dsk. The program executing on the PC is, of course, emulated by PC99W. It is not a PC executable.

If you do not purchase the TI disk, CaDD provides a method of creating it using the same terminal emulator on both the TI and PC. Ex: Terminal Emulator II, or Fast-Term.

If you no longer have a TI, then the CaDD-supplied 5.25″ TI disk serves no purpose. If you do not have a TI, or do not use this disk, PC99W will still operate correctly, and will not be affected in any way.

Final note: If you have a 5.25″ drive on your PC and try to
read the TI 5.25″ disk in it, Windows will return:

General failure reading drive BB
Abort, Retry, Fail?B

The reason for this is that the TI 5.25″ disk is not a Windows formatted diskette. It is a TI formatted disk that can only be read by a TI disk controller (TI, Myarc, Guion, CorComp, BwG).

As an alternative, the utilities supplied on the 5.25″ TI disk, can be used to create a series of disk dump files. These files can be copied to a PC-formatted 5.25″ disk in a TI system using PC-Transfer. This disk can then be read in a PC 5.25″ drive. This is much more difficult to do than the direct-connect method, and you must have PC-Transfer, a third-party program which is not included with PC99.

Why can’t TI disks be read directly on the PC?

Our understanding is that we will not be able to do this reliably.
The best we would be able to offer is a utility that
will read a TI disk in a PC 5.25″ drive and convert it to PC99 format.

The following points are offered to support this argument:

  1. If the operation is unreliable, it becomes extremely difficult
    for us to support. We simply do not have the resources to deal with
    every PC and every PC 5.25″ drive combination that might occur.
  2. TI disks are 5.25″. Most of today’s PCs no longer have a 5.25″ drive.
  3. We understand that “recent” PCs with 5.25″ drives, have had a signal
    line removed which makes it impossible for them to read TI disks. “Vintage”
    PCs may or may not work, since the PC controller has difficulty reading
    sectors numbered 0-8 (TI method) rather than 1-9 (IBM method).
  4. We found a company in California that was able to read samples of
    TI disks we sent them. They were willing to sell us their library for
    $2,500 with the caveat that it was not guaranteed to work with all
    5.25″ drives. The cost was prohibitive.

For these reasons no development is being done in this area. The PC99
product includes utilities that let you move your disk library to the PC.
The easiest way to do this is to have a TI and PC connected together
through their serial ports. The same utilities can also be used to
create disk dumps which can be transferred to a stand-alone PC using
PC-Transfer. PC-Transfer is a third-party product and is not included
with PC99. This method requires having a 5.25″ drive on the PC —
preferably 360K and not 1.2 Mb.

For people who no longer have access to a TI system, CaDD provides a
disk conversion service.

CaDD has an open offer to any programmer: Write us a
utility that will read a TI 5.25″ disk in a PC 5.25″ drive and
we will include it with PC99. You can do this as shareware and
we will include the shareware notice with PC99 if you desire.
We can also include your utility in the PC99 Add-Ons sections
on this web site.

Note: There is at least one published routine written in
C that we have tried that does not work on our test systems. We
have also tested a package developed by Gary Bowser that yields
very poor results.

Update 20000727: Paolo Bagnaresi of Italy has released
TI99-PC. The author claims this program will read TI 5.25″ disks
in a PC drive. The file can be downloaded from ftp.whtech.com.
Use an ftp client and log in as “anonymous”. Use your email
address for a password. The file is in the /utils directory.
This update is for information only. CaDD Electronics does not
endorse or support this program. Any questions about it should
be emailed to paolo_bagnaresi@libero.it.
Update 20130830.Paolo Bagnaresi d. August 22, 2013. The
email address is no longer valid.

What is CaDD PC99 Suite written in?

  • PC99W.
    Pelles C for Windows.
  • PC99W Disk Utilities, and PC99W Config.
    Microsoft Visual Basic 6 under Visual Studio 6 Enterprise edition.
  • PC99 DOS, cfg.exe, and utilities.
    Watcom 11.0c, and wasm. The Read Sector and Write Sector utilities
    to transfer disks are TI programs and are written in TMS9900 Assembly

Who are the CaDD PC99 Suite developers?

There are two developers: Eric Firestone, and Mike Wright.

  • Eric wrote the PC99W program and its debugger. PC99W is partially
    based on an early Windows version written by Mark van Coppenolle, which
    itself was based on PC99 DOS, which was mostly written by Greg Hill.
    Eric added considerable functionality to PC99W raising it to a level
    where it could be delivered as a product.
  • Mike conceived the project, writes the PC99 DOS utilities, writes
    PC99WDU and PC99WCFG, writes the documentation, writes The Cyc,
    maintains the CaDD web site, and is responsible for order handling.

CaDD would also like to thank the many people that helped in development.
In alphabetical order: Michael Becker, Mickey Cendrowski,
Dan Eicher, Larry Hoffman, Marc Hull, Klaus Lukaschek,
Ernie Pergrem, Stephen Shaw, Lee Stewart,
and members of the PC99W Beta Test Group on Yahoo.

Does PC99 DOS run under Linux?

PC99 DOS has been run under Linux using dosemu. View the how to instructions in pdf format by Dan Eicher.


CaDD had a machine running Fedora 13 and has successfully run
PC99 under DOSBox. If you have a problem running under any version
of Linux, first test PC99 DOS under its supported configurations
on a DOS or Windows machine. If it works, then we are unable
to support the Linux configuration. You should file a Bugzilla
report with the maintainer of your Linux distro.

Most Linux distributions are open source, and may be freely
disseminated. PC99 DOS is a proprietary product and may not be given
away for free in any format. This includes bundling it with
a Linux image. This approach is similar to products like Return
to Castle Wolfenstein from Activision. RtCW is sold to run under
Windows. It can also be run under Linux, but you have to own
the original Activision RtCW CD to do so. You must copy proprietary
files from the Activision CD to make RtCW run under Linux. The
same concept applies to PC99 DOS. If you make a Linux distribution
that will run PC99 DOS, it is your right to distribute this freely,
minus the PC99 DOS files that CaDD delivers. If the target user
is a registered PC99 owner, then your distribution can be used by that
user, once the required proprietary files are copied from the CaDD PC99
Suite DVD delivery media. If you create such a distribution, you
should supply clear documentation and/or a Linux shell script or
program to retrieve the PC99 DOS files and place them in your tree.

If you have a website where such a distribution can be downloaded,
please let CaDD know, and we will add a link to it if you desire.
You should also offer an email address for support questions.

The following information was written by and provided to CaDD by
Stephen Shaw of England. It explains how to run PC99 using dosemu
under Linux. The information is provided in .txt, .pdf, and .odt

.txt version

.pdf version

.odt version