Category: computers

It arrived!

It arrived! My 2nd Tandy 1000SX got here today, but the sound I heard when I took delivery was a bit ominous. It sounded like something rattling around inside. So I got it unpacked and opened it up. First, the case is a bit worse for wear. There is considerable rust on the chassis, and the plastic is a bit scuffed and has a couple of small cracks. Also, two of the slots don’t have covers, but there is clearly a modem in the eBay picks. So once the case is open, I discover the Tandy 1200bps modem lying inside, but also some sort of hard card lying loose as well. The hard drive is likely dead after banging around, but it was completely unexpected. Also, one of the ROM chips is a lot higher off the motherboard than in my other 1000SX, so it’s likely there is a smartclock in this one, so there’s that. Once everything was back together, I hooked up my monitor and keyboard and… 640K appears on screen, the 5.25″ floppy seeks, the 3.5″ floppy seeks, and “Non system disk or disk error” eventually appears. I put in my Tandy DOS disk and press ENTER, and it seeks the 5.25″ drive again, but fails to boot. I am uncertain whether it is the drive or the disk (I suspect the drive, as I believe I previously tested the disk in the other Tandy) but my troubleshooting stopped there, for now.

Some thoughts on this system: despite not getting a DOS prompt yet (and even if I don’t), I’m happy with this purchase. It works well enough to make a good backup to the other one, and the RTC and 3.5″ floppy can be moved straight over to it for immediate use. It would be awesome if I could get the hard card going, but it’s no loss if I can’t. If I can get to a DOS prompt, then I’ll likely restore this one too, but if not, the parts I’m definitely using are more than worth what I paid. 🙂

NEC V20 installed

I went ahead and bit the bullet and installed the NEC V20 CPU. I lose some compatibility, but gain some speed. I’m keeping the 8088 in case I decide to go back.

There’s a version of the XT-IDE ROM for 80186 CPU’s. I’m wondering how much performance improvement I’ll get if I update my card to use that version. But I’ll have to remember to revert back should I go back to the 8088, so maybe I leave well enough alone.

Are we there yet?

Are we there yet? No, but we’re getting close! That somewhat blurry image is my Tandy 1000 SX booting to a Compact Flash card. As part of the upgrades I’m doing to it, I picked up an XT-IDE card which included a 2 gig CF card, and now have more storage on my current Tandy than I ever dreamed of back in the day. Since the CF already had MS-DOS 6.22 on it alongside the XT-IDE utilities, and there were no conflicts between the default settings and the Tandy, installation was pretty much plug-n-play. Opened up the computer, plugged it in to an open slot, and powered up. Viola! Success! I believe DOS will support up to an 8 gig drive, so I may upgrade in the future. But for now, this will definitely do the trick!

Now I just need an easy way of getting software onto the CF. I have several “sneakernet” options, such as installing a 3.5″ drive in the Tandy, putting one of the 5.25″ drives into a desktop, or putting a CF reader into a desktop. Ultimately, I’d probably prefer to network the computer, and the Intel EtherExpress 8/16 seems to be the most affordable option that doesn’t require adapters to get RJ-45. 3com also made an 8-bit NIC with RJ-45 connector on it, but they seem to sell for considerably more on eBay. In the interim, I suppose I could make a null modem cable and run either ppp or slip between the Tandy and a Linux box. It will be pretty slow, as the UARTs on the serial card are 8250s, I believe, which will limit the speed to 9600bps or so. I supposed I should probably pull the serial card and find out for sure, and I could also upgrade the UARTs on the card to 16550 (if they’re not already), which will allow considerably faster speeds across the serial ports.

I also received the NEC V20 CPU that I ordered. I know I gain some extra speed if I install it, but I lose some compatibility, as the V20 is instruction-compatible with the 80186 instead of the 8088. I wonder if it is possible to piggyback them, much like the 6309 piggyback mod available for the Tandy CoCo.


Yesterday, I posted about some ideas for upgrades to the Tandy 1000 SX that I have on its way. The two most obvious ones are the NEC V20 CPU and the 8087 math co-processor.

Back in the day, Intel’s 80×86 CPU line did not include a built in math co-processor. You had to purchase and install one separately all the way up through the 486DX if you wanted floating-point operations. Not a lot of software took advantage of this, and I never installed one back in the day. Even my Pentium-class machine was a Cyrix 686, which was slower than Intel’s CPUs at floating point but faster in other areas. But it’s something I had always wanted in my Tandy 1000 SX back then, and they’re fairly inexpensive on eBay, so why not?

The other upgrade, which I hadn’t done to my Tandy but had done to another, generic, XT-compatible machine, that I plan on is to swap the processor with an NEC V20. It is pin-compatible with the Intel 8088 but will give you a little more speed at the same clock rate. (The XT-class machine I had one in also had a crystal hack done, which also provided a little bit of speed boost.)


After I get my Tandy 1000SX set up, here are some upgrades I’m considering to make it more useful:

I have a CGA to VGA adapter already that was in an arcade cabinet, but which is not in use, but I may need a different one as the board I have doesn’t support the intensity line, but, IIRC the CGA standard and, by extension, the Tandy graphics, requires it to get 16 colors. Without it, I believe only 8 colors will display.

Since it has dual 5.25″ 360K floppies, I’ll likely remove one and replace it with a 3.5″ 720K floppy, or, more likely, floppy emulator. I can then put the removed 5.25″ floppy in a desktop and give myself a way to create floppy disks.

There is no hard drive, so I will likely add an XT-IDE interface with a Compact Flash adapter. I always hated swapping floppies, so this, or at least the above floppy emulator, is a must for mass storage.

An 8-bit network card. Intel made an 8/16 model that is still reasonably priced on eBay. I could probably get away without the XT-IDE if I had networking, as I could mount a network share.

A Sound Blaster Pro. I like Tandy’s built-in sound much better than a standard PC, but, I prefer a sound card. And even though the SBpro is a 16-bit card, plugging it in to an 8-bit slot will still work as long as I don’t try to use a DMA channel that’s only available via a 16-bit slot. The SBpro also has a header on it that will take a speaker connector for input, allowing me to pipe the Tandy sound through it to external speakers. This gives me the best of both worlds when it comes to sound.

The SX I purchased appears to have a modem and serial card in it, so neither of those should be necessary. Since I would like to add a standard parallel port, I may replace the serial card with either a serial/parallel or a serial/parallel/game card, especially if I don’t add the SBpro above. I’m not sure if you can use the joystick port from either without conflicting with the onboard proprietary ports or not, but, if so, I wouldn’t hesitate to try. If I forgo the SBpro, if I get a parallel card, I can build a generic version of a Covox Speech Thing. IIRC I had built one back in the day, but can’t remember which machine I had it connected to.

Last but not least, I’m considering a VGA card. Obviously it’s better graphics that TGA, but I’m a bit torn on this one. Part of the charm of the Tandy 1000 line is the Tandy-specific graphics and sound modes.

Tandy Keyboards

Tandy keyboards are a bit of an anomaly. One of my retro computers, a Tandy 1000 SX, is still in transit, but, in the meantime, I’ve been doing research on keyboard options, as Tandy decided to use start bits in their keyboard protocol rather than stop bits, and, thus far, I’ve been unable to find anyone who has built a converter between the two. The Northgate Omnikey is one option, and there’s another non-Tandy option, but the name escapes my. I’ve also read comments about the Tandy 1000 keyboard being a hold over from the Tandy 2000, but I know the Tandy 2000 keyboard uses the same 5-pin DIN as IBM keyboards, but the Tandy 1000 keyboard uses an 8-pin DIN. It was unclear whether it was literally the same keyboard with a different cable, or it was just physically the same but with a different protocol. I finally tracked down the technical reference to both the Tandy 2000 and the Tandy 1000 and reviewed the keyboard sections, and discovered that they are, indeed, identical aside from the connector.

According to the technical reference manuals, both keyboards share the same scancodes and the same timings, and everything in the Tandy 1000 manual is also in the Tandy 2000 manual. The only difference I could find in that section of the manuals is that the Tandy 2000 manual includes the keyboard’s schematic, while the 1000 manual does not.

Finally, another Tandy anomaly is the naming of these two computers. The Tandy 2000 is the older of the two, and the 1000 is an entire line of computers that came after. I expect that Tandy updated the keyboard to the 8-pin DIN solely to cut confusion, as an IBM keyboards of the era had the same connector but was completely incompatible.

Retro computers

The first IBM compatible PC that the family had back in the day was a Tandy 1000 SX, which we had upgraded to 640K and, eventually, a 2400 bps modem and 40 meg hardcard. Eventually, I inherited this machine and when it became long in the tooth, I replaced it and gave it away. Now that I’m old enough to really feel nostalgia, this is the one machine I regret getting rid of above all others.

My wife, being the wonderful person she is, picked up a Tandy 1000 SX off of eBay for a really good price, and it is on its way here. From the pictures, it has dual 360k floppies, a modem of some sort, a dual serial port card, and appears to have been upgraded to 640k. What it doesn’t include is a CGA monitor or a keyboard. The monitor I can use an adapter for, but the keyboard isn’t compatible with many other keyboards in existence. There is a new-old-stock Tandy 2000 keyboard up for auction, but while the keyboard appears physically the same, it uses the more common 5-pin DIN instead of the 8-pin DIN of the Tandy 1000. I don’t know if they are the same aside from the cable or not. There is also a used Tandy 1000 SX keyboard available for a bit more. The 2000 keyboard is expensive enough that I’m not sure it’s worth risking incompatibility once the correct cable is built. So, I’m likely picking up a keyboard for more than the computer cost. 😉 There are some upgrades I plan for this to make it more usable, but I’ll detail those in future posts.

A fairly recent addition to my collection is a 64k Tandy Color Computer 2. I have no storage device for this, but plan on using a Raspberry Pi to overcome this.

I also have a complete Apple IIe system and a Commodore 64 system in my collection. I plan to eventually add a Tandy CoCo 3, a TSr-80 model 4p, and and early IBM…. I’m keepimg my eye out for a deal on a 5150, 5160, or 5170. I’d also like to have a 486-class machine and an original Pentium-class machine. I’m happy enough with emulation for these two that they’re nowhere near as high on my wish list, though.

Stay tuned for additions and upgrades, and a full report on the 1000SX once it gets here 🙂

A couple of DIY cpu / computer links

Here are a couple of links to homebrew cpu and computers that I thought my readers might finder interesting. The first is a homebrew CPU that I found on Hacked Gadgets. The Nibbler is a 4-bit CPU, hence the name (a nibble is half a byte).

The second link is a 3-chip retrocomputer via Hack A Day. It uses a 6502 CPU, much like the early Apple computers. I wonder if something similar could be done for the beloved 6809, as used in the Tandy CoCo

And now for something completely different…

I’ve decided that 2014 is the year that I finally really embrace some of my hobbies, and one of my greatest hobbies – the one I’ve turned into a career, in fact – is computing. I used to do it for fun, and I still do to some extent. But I’m not really talking social media and the like, I’m talking experimenting with operating systems, running a BBS, programming, retro-computing etc… So, among all the other things I’d like to tinker with in 2014, I’m considering digging out the CDs and installing OS/2 Warp 4.0 on one of my netbooks, and using that fairly exclusively for at least 30 days during 2014. I’m likely to cheat a little bit, as I have multiple Android devices that I’m not likely to give up, and I have to use Windows 7 on my work computer. Also, I may just set it up under a virtual machine in order to keep things fairly simple, and allow me to switch back to Linux after my experiment is over. Even if I don’t use it exclusively, the plan is to find software to use for the things I do daily, so that I could make the switch if I had to. This could be fun, and I’ll post my progress once I decide when to start.