After building a dual Pentium Pro computer (here), I started looking for a solution to host the full-length 16-bit ISA board I want to use with an MS-DOS powered computer. Since none of the remaining options available to me are cheap or rapid, I tried another path: pick an alternative computer. That’s when I thought about the Toshiba T5200 luggable computer. In my recollection, this computer cuts muster, and I was getting very excited about the idea of playing with yet another plasma screened Toshiba marvel. If you follow this blog, you know that I am fond of these computers and that I have the chance to own a few remarkable models (here, and here). As we will see later I was a bit optimistic about this one.
So, it is 1989, and Toshiba just revamped the top of the line of its portable computers with the T5200. Built around the i386 @20MHz with 32KB of static cache driven by an i82385, the T5200 was a rocket! Add an i387, and you have a supercomputer at your fingertips. Toshiba completed the system with 2MB of RAM (expandable to 8 MB), a 40 or 100 MB hard drive, and a 3.5″ floppy drive. As-is, the T5200/100 was clocked by the French SVM magazine as 366% faster than the IBM PC.
Other characteristics of the beast are 640 x 480 VGA graphics, 13″ Gas Plasma display, and support for an external color VGA monitor. The T5200 was, as you can imagine, very expensive for the time (over $2000 depending on the configuration) and was not a real laptop (39.5 x 37 x 9.9 cm for 8.9 Kg). Compared to the T5100 – the previous top of the line –, it is bigger but has a full keyboard with a numeric pad, and a useless lock. Interesting detail: an external floppy drive or printer can be attached to the DB25 port at the back of the computer. Prior to the boot, the user selects wich one it is via a small switch on the side of the machine (A:, B:, or LPT).
This computer has a fantastic build quality and a design for serviceability. Think about it; you can unplug the plasma display from the chassis while the computer is running, so you can shelve the computer under a monitor! The T5200 is the easiest Toshiba laptop I had to service, hands down. Coming back to my original problem, the T5200 has two ISA slots for a full-length (8 or 16-bit) and an 8-bit expansion board. With such a pedigree, I was very hopeful when I unearthed my T5200/100.
Now for the reality check. After 30 years, I faced several problems. Of course, as expected, the CMOS battery is dead. Less expected, the failure of the 100 MB HDD, as well as the death of the floppy drive. Quite disappointing, especially if you know that there is no boot-time accessible BIOS on these computers (same as on early Compaq computers). So, you must boot first and then run a setup program. Do you see a problem here? But wait, there’s worst to come. Indeed, Toshiba has locked the BIOS in such a way that you cannot change/upgrade much of the system without hacking the BIOS. True, you can find some of these hacked ROMs on the web, but now you must backup your own ROMs and burn new ones, hoping they will work for your system.
What applies to the BIOS also applies to the parts used by Toshiba. Do you want to add more memory? Then you must use the proprietary memory modules. What about replacing that dead floppy drive? Same bad news: it uses a Toshiba proprietary connection. Sure, you can work around these lockdowns, but it requires quite some re-wiring and BIOS changes. So, forget dropping in a GoTek floppy emulator or adding 8 MB RAM. Can it be worst? Always! The velvety smooth paint used by Toshiba – similar to the one used with some IBM ThinkPad – deteriorated over the decades and turned into a smush and sticky, very sticky surface. Argh!
After balancing the pros and cons of pursuing the T5200 route for my project, I decided to give it a try. First, I replaced the lithium 3.6V battery with a Mitsubishi part (there are many options on the market). Piece of cake. I also tossed in an i387, just because I could. Now that the BIOS will retain its information, I needed to access that bloody setup program (TEST3.EXE), so I can tweak the BIOS. I used an XT-IDE-CF OPTIMA 8-bit ISA board. That’s OK, as I only need the 16-bit full-length slot for my project.
With this board, I could boot into a 2GB MS-DOS primary partition on a CF card (thank you, PC BOOT ROMs). After running the setup program, I disabled the HDD and removed it physically. But when I did so, the system froze after the memory check, and I could not boot again from the XT-IDE-CF. Since the system booted with the dead HDD, I plugged in the HDD interface an inexpensive IDE to SD adapter (SD SDHC MMC), the same model I used for the dual Pentium Pro system. It worked. Note that there is no need to install an SD card and that the cable alone doesn’t do the trick. In the future, I may try building a custom cable for a standard FDD or floppy emulator, but it is not my priority.
The sticky case is a problem for me; it makes the use of the T5200 unbearable. None of the solutions I found on the web convinced me. Either they were questionable, or just a temporary fix. If it turns out that my mysterious piece of hardware – the one that needs the 16-bit ISA slot – works in the T5200 (really, only the PSU can fail me at this point by browning-out), then I will completely disassemble the T5200 and scrap off the sticky coating. Finally, I will commit sacrilege and repaint it vermillion with some custom vinyl marking! If the PSU does betray me, I will resume the dual Pentium Pro route. Stay tuned.