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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.


  1. Hey thanks for d article bro! Incredibly helpful.

  2. Wow, I remember that PC. This was my second computer. First was the Commodore Vic 20 GHM……..

    • The C64 was my very first computer. I actually have a Vic 20 here but I don’t have a power supply for it. I really need to track one down or just bite the bullet and grab one of Ebay.

  3. Hey William Bogardus! My first PC was a Vic 20 and my second was a Tandy 1000A 🙂 Did you ever get Tank vs UFO correctly programmed? Miine always had a lot of funny bugs in it

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