The TX-0 (Transitorized eXperimental computer 0) was built to aid in the testing of it's big brother, the TX-2, and many of the features used in the TX-2 were first tested on the TX-0. This was one of the reasons why the TX-0 was originally equipped with 64Kword memory (each word being 18 bits). When work on the TX-0 began, it was not clear if such large magnetic core memories could be built.

The memory was stripped down to 4Kword memory when it was delivered to RLE but was later upgraded to 8Kword. The 18 bit words used 16 bits to address the original 64Kword memory leaving two bits for instructions. When it became apparent that it would never be equipped with its original 64Kword memory, the three unused address bits were used to add a set of new instructions.
Transistors

The transistors used in the design were made by Philco and were the last of a series of high-speed transistors. Unfortunately, they were rather expensive, costing several dollars a piece, and very delicate. Even the slighest electrical discharge, such as one gotten from having combed your hair before touching one, would burn them out.

Each transistor was placed in a "bottle"-shaped container for easy placement on the boards. Every type of transistor would have its container marked with a specific colour such that if one transistor broke, you could easily replace it with one of the same colour.

== Equipment ==

* Speaker - A speaker was connected to the TX-0 console. It was controlled by the state of the 14th bit of the accumulator.

* Flexowriter - The most important piece of equipment was the flexowriter, and all-in-one keyboard, printer, paper-tape reader and puncher. There existed several "off-line" flexowriters for preparing programs and creating paper tapes, but the "on-line" flexowriter didn't use its tape reader. The paper punch though was used mainly to output binary copies of assembler input.

* Tape reader - The additional photoelectric reader was a high-speed reader that was used instead of the built-in reader on the Flexowriter. It was capable of reading 200 to 250 lines per second and was of a standard seven-hold type.

* CRT - While CRTs was not unheard of in the industry at the time, the TX-0's CRT was particularly easy to use, a feature which would later be carried over to the TX-2 and the PDP-1. The CRT used was a 12 1/2" oscilloscope display with 511x511 points in a 7" by 7" array.

* D/A and A/D - Two rack-mounted devices that converted audio to digital format and vice versa.

* Tape drive - Gordon Bell added a 7-track IBM magnetic tape drive to the system.