Tandy also regained a significant share of the Apple-dominated educational market, which the two companies had once equally shared. The 1000 and its many successors were successful unlike the PCjr, partly because it was sold in ubiquitous Radio Shack stores and partly because the computer was less costly, easier to expand, and almost entirely compatible with the IBM PC. The PCjr's enhanced graphics and sound standards became known as "Tandy-compatible". With its graphics, sound, and built-in joystick ports, the 1000 was the best computer for PC games until VGA graphics became popular in the 1990s. Software companies of the era advertised their support for the Tandy platform; 28 of 66 games that "Computer Gaming World" tested in 1989 supported Tandy graphics. Tandy 1000 computers were some of the first IBM PC clones to incorporate a complete set of basic peripherals on the motherboard using proprietary ASICs, the forerunner of the chipset. Although the original Tandy 1000 came in an IBM PC-like desktop case, some models, notably the 1000 EX and 1000 HX, used home-computer-style cases with the keyboard, motherboard and disk drives in one enclosure. This high level of integration made these machines a cost-effective alternative to larger and more complex IBM PC/XT and PC/AT-type systems, which required multiple add-in cards, often purchased separately, to implement a comparable feature-set to the Tandy 1000. Being derived from IBM's PCjr architecture, the Tandy 1000 offered several important features that most IBM PC-compatibles of the time lacked, such as the PCjr's sound generator and extended CGA-compatible graphics controller. It also offered multiple built-in I/O ports, including a joystick port which was frequently a separate add-on card on non-Tandy machines. The original line was equipped with the Intel 8088 CPU, which was later extended to faster clock speeds and also the 8086, 80286 and toward the end of the line with the RSX, 80386SX processors. Successors to the 1000 appended two or three letters to the name, after a space (e.g. Tandy 1000 EX and Tandy 1000 HX). In a few instances, after these letters a slash was appended, followed by either a number or additional letters (e.g. Tandy 1000 TL/2, Tandy 1000 RL/HD). By 1993, changes in the market made it increasingly difficult for Tandy Corporation to make a profit on its computer line.