the RC circuits warmed them up, the electrical properties of the RC timebase would shift, causing the oscillators to drift in frequency to a point that they could no longer be synchronized with the received pulses coming from the TV station via the sync separator circuit, causing tearing (horizontal) or rolling (vertical). Hermetically sealed passive components and cooler-running semiconductors as active components gradually improved reliability to the point where the horizontal hold was moved to the rear of the set first, and the vertical hold control (due to the longer period in the RC constant) persisted as a front panel control well into the 1970s as the consistency of larger-value capacitors increased. By the early 1980s the efficacy of the synchronization circuits, plus the inherent stability of the sets' oscillators, had been improved to the point where these controls were no longer necessary. Integrated Circuits which eliminated the horizontal hold control were starting to appear as early as 1969. The final generations of analog television receivers (most TV sets with internal on-screen displays to adjust brightness, color, tint, contrast) used "TV-set-on-a-chip" designs where the receiver's timebases were divided down from crystal oscillators, usually based on the 3.58 MHz NTSC colorburst reference. PAL and SECAM receivers were similar though operating at different frequencies. With these sets, adjustment of the free-running frequency of either sweep oscillator was either physically impossible (being derived inside the integrated circuit) or possibly through a hidden service mode typically offering only NTSC/PAL frequency switching, accessible through the On-Screen Display's menu system. Horizontal and Vertical Hold controls were rarely used in CRT-based computer monitors, as the quality and consistency of components were quite high by the advent of the computer age, but might be found on some composite monitors used with the 1970s–1980s home or personal computers. There is no equivalent in modern television systems. Other technical information Components of a television system A typical analog monochrome television receiver is based around the block diagram shown below: The tuner is the object which "plucks" the television signals out of the air, with the aid of an antenna. There are two types of tuners in analog television, VHF and UHF tuners. The VHF tuner selects the VHF television frequency. This consists of a 4 MHz video bandwidth and a 2 MHz audio bandwidth. It then amplifies the signal and converts it to a 45.75 MHz Intermediate Frequency (IF) amplitude-modulated