Compucolor.org - Home > 자유게시판

Because it used the raw 5501 serial data stream, within the worst case there is likely to be eight '0' knowledge bits following the '0' start bit before the final '1' stop bit. To save cash, Compucolor purchased the uncooked drive mechanism from Wangco (later bought by Siemens) and used their own drive electronics. It would have been easy enough to initialize those CRTC registers from a desk in ROM, however the Compucolor design didn't do this. Although the Compucolor was constructed right into a Tv set cabinet, the electronics weren't that of a regular Tv. This chip had sixteen registers, some readable, some writable, to regulate show timing and to set the place of a hardware cursor. If the CPU accesses the display RAM at the identical time the video generation logic does, the CPU wins and there's a visible "tear" in the video stream. It means the info stream might need lengthy-term DC content, but the recording medium is incapable of tracking it; it additionally implies that there are not any illegal bit encodings, such that there are not any straightforward to tell apart encodings to make use of to sync to; it additionally implies that the learn logic can't use AGC (computerized acquire control) and will need to have an absolute threshold for distinguishing a one bit from a zero bit.

This similar logic is used to serialize/deserialize data to/from the floppy disk. We could do the identical by rising the incoming sign power by 3 dB (to 4 uV). In other words, the strength of the detected RF changes by twice the number of dB, low voltage power cable that the sign adjustments. That's to say, the energy of the RF sign detected, increases or decreases to the sq. of the RF level at the junction detecting the signal. There is a strategy to measure SNR comparatively, but it surely does require a bit of hardware, and a stable sign supply. One can simply current a case, where an increase in antenna efficiency of just 1 dB, can make a significant change in the SNR. So the bottom line is; with correct filter decisions, proper antenna selection, correct mounting, and correct noise suppression and abatement, we can achieve straightforward copy, instead of nothing however background noise! Each sector begins with about 10 byte occasions (a hundred bits, or 130 us) of hole -- nothing but mark ('1') state and no transitions. If the disk velocity is off by a number of percent, particularly if the system which wrote the sector was totally different than the system studying it, bits could be dropped or inserted.

The rationale the memory mapped video handle range is duplicated is to allow a commerce-off between velocity and quality. There was no have to module and demodulate the video signal: the graphics generator drove the CRT crimson, inexperienced, and blue guns immediately. In the traditional handle vary, the place the consumer is typically simply poking a byte at a time while typing or printing text, stalls the 8080 CPU till the horizontal blanking interval, at which level the video era doesn't need to access RAM. At a later point they switched to a four-section stepper design; although the interface is identical, the part controls are decoded into a 4 part drive to the stepper motor. The insides (pictorial) of the Sinadder are proven at right. An instance is shown in the photo. The primary file appears immediately after the last sector reserved for the directory entries, and is allocated contiguously. All sectors after the final file are "free", and are used when the subsequent file is written. FCS views the disk as four hundred sectors, sector 0 by sector 399. Sector zero starts with a small descriptor indicating how many sectors are to be used for the disk directory, and in addition incorporates a 10 byte volume label.

Because recordsdata are only ever appended to the directory, saving FOO.BAS to disk, modifying it a bit, then saving it again will result in two entries: FOO.BAS;1 and FOO.BAS;2. There are several models, but any of them will do the job. There are two classes of cheap devices obtainable for making non-contact distance measurements. Helper is out of enterprise, and their successor stopped making the device. This guidelines out about 80% of the current batch of commercially accessible, remotely tuned, HF antennas. To deal with the first downside, the software blindly steps the r/w head out forty two times when it wants to residence the top to track 0. The source code for FCS literally calls this the POUND routine. When studying a sector, the software program discards the primary few few bytes is may learn until it sees the 0x5A sync byte. To solve this, the formatter writes three dummy 0xFF bytes between the ID block and the data block. It also had a row offset register, allowing an environment friendly scrolling of the display with out having to shuffle all of the bytes to impact the scroll.