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In some of my earliest articles I covered a few iterations of the popular Tandy 1000 line. The Tandy 1000A as well as the Tandy 1000HD and the compact Tandy 1000 EX and HX but now I’m going to shift to the end of the true Tandy 1000 line and talk about the Tandy 1000RL-HD the last of the 1000 line to be truly PCjr compatible.


As you can tell right away the 1000RL is a slim-line design and the machine is surprisingly light. You have a power button to the far right with a 720kb 3 1/2 floppy drive seated next to it. There is another bay for a second floppy drive but I don’t think a dual floppy RL version was ever sold, though I could be wrong. My model is the hard drive version which is slightly upgraded from the regular RL. You can tell easily which version your getting via the faceplate.

Both the RL and RL-HD come with a 8 bit IDE interface on the motherboard for a hard drive. This is the same style interface as found on machines like the Commodore Colt and in all honesty is not terribly useful. The drives are fairly uncommon and less then 40MB in size. My machine came with the original 20MB Seagate ST325X drive. The drive is very loud powering up and can be unreliable.


The HD version of the RL besides sporting a hard drive stock also has a battery-backed real time clock chip on the motherboard which the regular RL lacks.

The rear of the machine has two levels of ports.



On the far left we have a standard power port for a three prong power cord. Starting on the top left we have a serial port followed by two Tandy 1000 joystick ports, a stereo audio jack for speakers or headphones and a mic jack. Lastly on the top level we have a volume knob for the pc speaker which is a very nice addition. I think the knob would of been better placed on the front of the machine somewhere but its inclusion anywhere is always welcomed.

On the bottom row starting from the left we have a standard CGA port which will output CGA and of course Tandy Color Graphics or TGA as well as monochrome. The 25 pin printer port looks standard but unfortunately it supports no input so its basically a printer only port. Finally we have two ps/2 style ports. Now I say style because of the keyboard port. The mouse port is basically a ps/2 port and depending on the driver used you can get many ps/2 mice to work just fine. I was able to get a more modern ps/2 laser mouse working fine with Cutemouse drivers. The keyboard port though is not quite standard even though physically speaking it is ps/2 compatible. This machine requires an XT keyboard with a ps/2 style connector like the Tandy Enhanced Keyboard that came with this machine.


Otherwise you would need to find a XT keyboard and use an adaptor of some sort.

There is only one 8 bit ISA expansion port available on the rear of the machine making expansion very limited. On the question of adding video or sound cards, you may also of noticed the 1000RL lacks a composite port that was present on earlier Tandy 1000’s. Adding a CGA card with a composite out could be an answer to this issue though. On the sound card front keep in mind that using a Sound Blaster 1.0 or 2.0 may cause freezing under certain circumstances due to conflicts with devices using DMA 1.

The best option in my opinion for the expansion slot would be some kind of 8 bit IDE hard drive controller.

The case is relatively easy to remove and only requires the unscrewing of two screws.


The motherboard for the 1000RL is very compact. It’s basically a laptop sized board in a desktop case. This machine also has Tandy Deskmate and DOS 3.3 built into ROM so a hard drive is not needed to boot up and then access a floppy disk which is very nice.

Video – The video on the Tandy 1000RL uses an enhanced version of TGA known as ETGA which has all the old modes of the TGA plus a 640×200 with 16 color mode


1) Pc Speaker


2) riser card – this card contains the rear joystick ports, serial port and audio jacks as well as the volume knob. It is connected to the main board via a connector. The chip directly in front of the riser is I believe the PSSJ chip which controls the audio and ports on the riser.




3) CPU – the 1000RL CPU is an AMD 8086 running at 9.56mhz though there is an option in BIOS to set the speed to 4.77mhz or by typing “MODE SLOW” in Tandy DOS and “MODE FAST” to return to 9.56mhz. As I’ve mentioned before the 8086 in most circumstances performs faster then the 8088 at equivalent speed so some old game MAY have issues. This speed can be a benefit though for some games such as Digger that may run a little to slow on something like the PCjr. The CPU though is soldered onto the motherboard and not socketed thus it is impossible to replace it with a NEC V30 for more speed.




There is also no socket on the motherboard for a 8087 math co-pro but since hardly any games take advantage of one this isn’t much of an issue.


4) RAM – The standard RAM on the RL is 512kb but this can be expanded to 768kb (640 DOS, 128kb for video) via two 256k x 4 DRAM chips.


5) The regular 1000RL has a socket for an added real time clock but the RL-HD has one built into the motherboard using an easy to replace lithium coin battery.


6) One 8-bit ISA slot.


7) IDE-XT Interface – Both the RL and RL-HD have a IDE-XT 8-bit interface built into the motherboard. This interface only works with a small number of hard drives all being under 40MB.


8) Floppy Interface – The non standard floppy interface is typical of Tandy and supplies the power via the floppy cable to the drive.


9) PSU


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The Tandy 1000RL-HD has its problems. The built in HD interface was a dead end and there are some minor game incompatibilities but overall it makes a good Tandy machine. It supports TGA graphics as well as 3 channel audio sound and has a slow enough CPU to play most of the games that support those options just fine. Its also extremely light and small taking up little desk space. The fanless design means without a hard drive or when using a CF as a hard drive the machine is dead quiet and invites very little internal dust. The fact that DOS and Deskmate are present in ROM also alleviates some issues such as always needing a DOS boot disk handy to get into the system. They seem to be fairly common and reliable models so if you can find one for a low price its a no brainer to pick it up.


At first I was just going to roll this article in with my Tandy 1000A article I did awhile back but after more research I found out there wasn’t a whole lot of specifics out there on the 1000 HD so in the end I think it deserved its own post, even if it is a rather short one.


The Tandy 1000 HD looks pretty much identical to the standard Tandy 1000 and 1000A. The HD doesn’t stand for “high definition” but “hard drive” and as a matter of fact before I got this unit I just assumed it was a Tandy 1000  with a hard drive and controller card slapped inside by the factory….and it is but at least they went through the effort of badging it differently as well as add a ram and DMA card (at least I think the ram/DMA card are stock from the factory.

t1000hd2Simplest way to tell its a 1000 HD, check the badge on the front


As we can see from the back the 1000 HD uses the same wattage power supply as a 1000A and I assume 1000. If you look on the right at the expansion slots you can see the cards are sticker labeled. The middle card is a modem which I don’t know if it was added later or came standard from the factory but the memory PLUS card does specifically say Tandy 1000 HD so I suspect it came stock with the hard drive controller card which would make sense as The extra memory and DMA controller would be very helpful with an added hard drive. All the other ports are same as on a stock Tandy 1000.


Here is the machine after being opened with all three expansion slots filled. Notice the massive hard drive circa early 1980’s. Its so large that they had to install it parallel with the case rather then a more traditional bay setup. These drives installed factory were in the 10 to 20MB range. I don’t have a Tandy keyboard at the moment (you need one, its a proprietary keyboard port) so I couldn’t do much checking. On powering mine up it gives a boot screen and a memory check of 640kb but then nothing so I assume my floppy drive and hard drive are dead. My motherboard and power supply seem in fine shape though.


Here we have the motherboard with the expansion cards removed. Comparing images It seems to use the exact same motherboard as the standard Tandy 1000 and you can see no slot for a 8087 next to the CPU. Mine seems to have a rather low serial number so I’m not sure if later models of the 1000 HD used the improved 1000A motherboard but from what I could find they do not. I could not fully remove the hard drive and floppy drive cover and holder because one screw is particularly hard to get if not impossible with standard tools unless I wanted to go through a lot of trouble or damage the brackets securing the hard drive so I left it alone. I assume Tandy expected you to ship the unit back to them if you ever decided to replace the hard drive.

Now for the two important expansion cards that I believe must of came stock with this PC to facilitate the added hard drive.


Here we have the 8-bit hard drive controller card. A Western Digital wd10025-wx2 controller card. the Bios “G” version of this card can handle 10 and 20mb hard drives as seem stock on the Tandy 1000 HD but cards with a “H” Bios can handle drives up to 62MB in size. Its not a proprietary controller card so you could potentially pull and use this controller in any old PC you have that requires an 8-bit hard drive controller for MFM drives.


Lastly is the Tandy memory PLUS expansion card. This card bumps the RAM up to 640kb and adds a DMA controller or “Direct memory access” controller to greatly help speed up hard drive and various other operations. I believe the pins in the lower right hand of the card are for an optional RS-232 serial port expansion.


Finally we have the Tandy 300 baud modem. I don’t really mess with old networking and what not so not much to say about it.

I would say if you can find one of these machines for a reasonable price or free the 8-bit hard drive controller alone is worth the effort not to mention the nice Tandy memory expansion PLUS card. A fully working system would also make a nice vintage gaming machine for the early era of PC gaming plus you get a hard drive and that great Tandy graphics and sound.

The Tandy 1000 line of computers was a pretty important and well known computer line of the 80’s. Based off of IBM’s failed PCjr It had superior sound (Tandy 3 channel) and video (Tandy graphics which was a improved version of CGA looking very similar to EGA) when compared to other IBM PC’s of the time that used a PC speaker and CGA or Monochrome graphics. If you want to learn more about the details or Tandy graphics there are tons of informative pages on the net and I would suggest starting at Wikipedia or here. I recently acquired a Tandy 1000A for about $10 with an accompanying Tandy  CM-4 RGB color monitor (just an older version of the CM-5 but basically identical). So what is the Tandy 1000A and how is it different from the original? Cosmetically and functionally they are pretty much identical except that according to Wikipedia the 1000A “fixed bugs, scanned expansion cards for bootable ROMs, and added a socket for a math coprocessor”. Since there is already so much information on this particular computer and not a whole lot for me to add I’m just going to briefly go over it here and point out the differences between the original Tandy 1000 and the slightly later 1000A revision so you know which one you have.

unfortunately the Tandy 1000A I bought did not come with a keyboard and I suspect both 360K 5 1/4 floppy drives no longer function. To speak for the Tandy’s build quality I purchased 2 other computers at the same time both mid 90’s Pentium 1 rigs. They both failed to boot (most likely a power supply issue) while the Tandy booted right up. The front is identical to a stock Tandy 1000 even down to the name plate. you have the two disk drives, big red self destruct button…errr reset button. a keyboard port proprietary to the Tandy so you cant use a standard IBM keyboard and finally two joystick ports. The power switch is on the right hand side at the rear.

The back is also identical for the most part to a standard 1000. from left to right we have the parallel printer port, light pen port (not a serial port and pretty much useless) and RGB monitor port (for CGA monitors), composite a/v out in case you don’t have a monitor you can use a TV set and finally a mono audio a/v out.

also on the back we have the first and easiest way to see if you have a 1000A.

Take a look at the model number written above the boxed serial number. If it says 25-1000A then you have a 1000A….most likely. It is possible that someone at some point damaged the case and swapped motherboards putting a 1000 MB into a 1000A case. If you want to be completely sure we need to open it up and look inside. Fortunately this is incredibly easy and requires removing 5 screws, 2 in the front and 3 in the back.

(click to enlarge)

Here we have the motherboard, usually the entire right side is obscured by the power supply, floppy drives and aluminum casing which I have temporarily removed.

1) This is the empty slot for an optional 8087 math co-processor. This slot will not be present on a standard Tandy 1000 and was the biggest obvious addition to the 1000A. The addition of a math coprocessor would speed up the computer when running some programs and math intensive applications.

2) This is the 8088 CPU of the 1000A, the same CPU as in the 1000. The CPU runs at 4.77MHZ (or 4.6 by some independent benchmark tests) and can be upgraded to a NEC V-20 chip to improve performance (only works in about 70% of Tandy 1000, 1000A’s). I plan to go into more details at a later time, perhaps if a do an “Anatomy of” feature on the Tandy but as of now I’m just going to quickly go over the basics.

3) connection for the power supply. it looks like AT but i believe it is proprietary.

4) this is the floppy connector for the two 5 1/4 floppy drives.

The Tandy 1000A like the 1000 comes with 3 8-bit ISA slots.

This a single slot 8 bit ISA memory card for the Tandy.  It has 512k of RAM on board bringing the total system RAM to its max of 640k. This card also has a DMA chip or (Direct Memory Access) on board increasing IBM compatibility. Later versions of the 1000 like the SX had the DMA chip as well as the potential 640k of RAM on the motherboard itself.

The Tandy 1000A is a slight upgrade from the stock 1000 and is not difficult to differentiate once you know what to look for. In the end though it pales in comparison to the later SX, TX and even the compact EX/HX Tandy 1000’s which offer much more expandability and features while maintaining the same compatibility for the early Tandy era games and applications.

picked up Tandy 1000EX system in great condition with the boxes. I still like my Tandy 1000 SX better but at least this model has a volume control for the internal speaker. it also came with the 640k ram expansion and a modem, I never use modems in these old computers though. The main attraction to the Tandy series of computers is there almost perfect IBM compatability but also with the improvments introduced with IBM’s PCjr such as Tandy Graphics and improved sound.

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