Were you a huge fan of the best selling Commodore 64 computer in the early 80s? Did you love it so much you just wished you could bring it along everywhere you went? Well, if so, in 1984 you were in luck because that’s when Commodore released the SX-64 or sometimes called the Commodore Executive, a Commodore 64 “luggable” computer. The SX-64 was a Commodore 64 computer, complete with floppy disk drive, keyboard and a small 5 inch color CRT monitor all in one briefcase style package. It was heavy and bulky like a large briefcase and still required the unit to be plugged into a wall power supply but in the early 1980’s this was the norm for portable computers.
The keyboard of the SX-64 also acted as the front cover and attached over the front of the machine shielding the monitor and single floppy drive. The handle on the case doubles as a stand when the SX-64 is in use.
With the front cover / keyboard removed by pressing down and two small plastic tabs the front of the SX-64 is revealed. On the far left we have the 5 inch composite color CRT monitor. Next to that we have one Commodore floppy disk drive and what looks like a storage area above it which is actually….well, a storage area and is labeled as such. There were plans to release a SX-64 with two floppy disks drives named the DX-64 but details are a bit sketchy on if this version was ever actually officially released. A few have turned up over the years but they seem to be exceptionally rare. I’ve read some SX-64 owners have indeed added a second drive in the “storage area” so it can be done. Usually this little storage bay is used to stow the keyboard cable when the SX-64 is not in use.
On the far right we have a small door with the C64 branding behind which is some basic control knobs and pots to control sound volume and adjust the monitor.
The 5” color composite monitor itself is small but very easy to read and I found mine to be quite sharp and gave a better looking image then I expected.
Spinning the SX-64 around we can take a look at the back and the various ports.
Starting from the left we have two joystick / mouse ports followed by an A/V out port meaning that you can easily connect the SX-64 to an external monitor or TV if you wished. Next to this is a Commodore serial 488 port for connecting things like an external disk drive or printer. In the center we have the edge connector like Commodore user port which connects to some printers, modems or even other computers. Lastly to the far right we have a standard three prong power connector, a fuse and a power on/off switch. My unit interestingly does not have the port labels molded into the plastic next to the relevant ports where I have seen some models that do.
Located on the top of the SX-64 is the cartridge port.
The keyboard connects to the main unit via a non-standard 25-pin keyboard connector. The connector on the SX-64 itself is located below right side of front panel and is a little awkward to reach and connect in my opinion.
Finding an official replacement cable if yours is lost or damaged can be difficult but homemade replacements can be found on eBay in the $25 and up price range. They generally aren’t as nice looking as the official cables though.
Lets take a quick look inside by removing several screws on the side.
The internals of the SX-64 are extremely cramped and hardware failures due to excessive heat are not uncommon. On the left side we mostly have the CRT itself as well as the speaker and behind that the power supply. Directly behind the cartridge slot is the board with the keyboard controller and the panel on the far right is the board hosting things like the CPU, RAM and PLA chip.
Common issue with PLA chip
On powering my SX-64 up for the first time however I was greeted by a very pixelated and distorted screen.
This is a rather common issue caused usually by heat and a faulty PLA chip. Thankfully this chip is socketed and is fairly easy to get to and replace.
Below is an image with the bad chip highlighted. Even though it’s relatively easy to reach you probably are better off disconnecting the board and raising it out of the case for better access. There are some excellent guides online and on YouTube detailing this process.
And here is the offending chip once removed.
I opted to replace my PLA chip with a more modern equivalent. I found my online for about $25 and as far as I can tell it is 100% compatible and generates significantly less heat.
I even decided to add a small heatsink just for extra cooling though with a more modern replacement part like this it’s not necessary.
If you experience keyboard issues you may also want to make sure the connection with the board directly behind the cartridge slot and the main board are making a solid connection as seen below.
Thankfully this simple and fairly cheap fix solved all my video issues and if you have issues with your SX-64 I would suggest looking at replacing the PLA chip first. There are other chips that may go bad including the RAM which unfortunately is soldered on but I have found a bad PLA chip is usually the issue as far as a black or distorted screen goes.
Overall compatibility with the SX-64 seems to be pretty good though I’ve read there are issues with certain games and peripherals such as RAM expansion units and some printers. Due to the default screen color being changed to blue text on a white background some programs may experience issues since they expect the default white text on a blue background.
I like the SX-64 but I don’t really find it that useful as I would strongly prefer a standard C64. The SX-64 didn’t sell that well back at release. The C64 was never really seen as a serious business machine and in my mind packing a breadbox C64 as well as the floppy drive, PSU and a few cables into a small box and just using a larger TV as a monitor if you’re going on vacation or something isn’t much more of a hassle or less of an inconvenience then lugging the SX-64 with you. Yes, it is more convenient and if you needed a C64 and traveled a lot or did demonstrations it would be really helpful but for a retro gamer today it’s an interesting piece for Commodore fans but I’d stick with a good old C64 or C64c for my actual C64 gaming.
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