Tandy 2000 Restoration


August 5, 2007

Ok, so I haven't been so good in keeping up with the log. I've had other projects get in the way, and finding a CM-1 monitor proved to be a huge challenge. Here's what I've accomplished so far:

After all of this, I now have a very solid 640k 2000HD system that I also upgraded to dual floppy drives (taking the other from my other machine).

Other things I've discovered:

Now that this is done, I have to pull together all of the disk images into one place. Then, I have to scan the Technical Reference Manual. That one is going to be a pain because it's spiral bound. I also want to connect the failed hard drives to an MFM controller in a regular old PC and see if maybe I can waken them.

November 21, 2006

I've made images of most of the disks using Teledisk. Some of the disks, for whatever reason, were not readable. Fortunately, the programs exist on the hard drive so I should be able to regenerate the bad disks from the copies on the hard drive.

The bad news is that the hard drive has become flaky. It worked fine initially but now it spins but doesn't go "ready" so I keep getting "bad unit" errors. Oh well.

I have another MFM drive and I'm hopeful I can get the old drive working one more time so I can copy everything to a new drive.

November 12, 2006

I'm getting closer to powering up the T2k for the first time tonight. The first thing I did was to make copies of the BIOS EPROMs. Indeed, they are TMS2532JL-35 EPROMs. U47 (high/odd) contains a label with "474600" on it. U48 (low/even) contains a label with "484A00". I presume that these are checksums but right now I have no way to tell.

Here is a zip file containing the binary ROM dumps for burning replacements.

After cleaning the keyboard I plugged everything in and gave it a whirl. The machine powered-up without a problem! It reports MS-DOS version 2.11.03 and a BIOS revision of 02.02.00. Perfect!

Next thing for me to do is to make images of all of the disks.

November 11, 2006

I started cleaning the Tandy 2000HD system unit I received (26-5104 serial M5405732). A quick system inventory reveals that it has only one floppy drive in addition to the 10mb hard drive. The expansion card cage contains, from top to bottom, the following cards:

This configuration would imply a system with 640k of memory. Not too bad, and more than my first PC had (128k I think).

The system is in good physical shape but the case is severely yellowed and smells musty. I opened the unit and using compressed air and a brush, blew out the dust. I opened the power supply and looked for any obvious signs of previous trouble (none), and then I blew out the dust. Two screws that attach the front fascia to the case were missing so I replaced them.

I gave the outside a quick cleaning with Simple Green just to de-grime it. At this point I turned the system over so I could get to the planar cage. I removed the four screws holding the cage to the case and the two screws that hold the cage to the riser connector and with a little tug to unseat the Euro connector, it hinged upwards. Again, another quick dusting.

The first thing on tap for tomorrow is to remove the two BIOS ROMs and make copies. Interestingly, the ROMs weren't even mask programmed ROMs -- they were TI 2532 EPROMs with a label upon which is printed what appears to be a checksum. According to what I've read, the BIOS version is 02.00.00 but that somehow doesn't reconcile to the fact that they used EPROMs (and it also implies that there were earlier revisions). Tandy made, what, 10,000 or 12,000 of these machines -- each with two EPROMs. It had to be more cost effective to run 20,000 masked ROMs than buy and gang program the same number of EPROMs. Maybe someone can shed some light on this for me.

That's it for now.



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