One obvious product was to place eight KB of RAM there, and another product put an socketed EPROM that filled that deal with vary, allowing storing varied preloaded programs, resembling an assembler and debugger. One product even allowed stacking eight 8 KB banks into that one vary, with software choice between which bank was lively at any given time. Because it used the raw 5501 serial knowledge stream, within the worst case there might be eight '0' data bits following the '0' begin bit earlier than the ultimate '1' cease bit. The 5501 has a easy RS-232 type serial interface: one begin bit, eight data bits, one cease bit, costing 10 bits per byte. 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 chip had five timers, not all of them had been used by the Compucolor II. The opposite mode, described later, used an undocumented function of the chip to drive the floppy interface. The electrical interface was somewhat easy, and anything not strictly crucial was not supported. Unlikely most contemporary (or trendy) disk system, the file system software program was burned in ROM and thus could not ever be enhanced.

Most different system have a tiny ROM routine to learn a boot sector from the disk, which then loads in a 2nd level disk operating system, allowing for bug fixes and enhancements after the very fact. Once the best observe and sector are found, the software program switches on the write allow after which writes the information block. Imagine having a one millisecond of no bit transitions then all of the sudden getting a burst of 1s and 0s and having to decode them flawlessly; it's a tricky downside. I have A ninety nine daewoo Lanos with the same problem. See Henry Ott, Noise Reduction Techniques in Electronic Systems, 2nd ed., John Wiley & Sons, 1988.) There are shielding approaches that provide a low floor switch impedance at high frequencies, while at the identical time offering a much greater impedance at 60 Hz. In the example you cite, the ground transfer impedance at one end of the cable would be one hundred ohms, rendering the shield ineffective. It gives a direct metallic connection between chassis and shield that goes all the way across the connector pins, fully enclosing the signal conductors.

Grounding both ends of the shield permits high-frequency currents to circulate in the shield, which can counteract the currents flowing in the signal conductors. They're used the place excessive-frequency shielding is required, but the place there's a want to limit the circulation of 60-Hz currents. Once other overheads are factored in, the disk format saved 10 sectors of 128 bytes per sector, or 1280 bytes per track. The 3-section floppies had one step per track, but the 4-section floppies had half the step measurement, requiring two steps per observe. Instead, it seems to maneuver one file at a time. When a file is deleted, FCS will shuffle down all the files which come after it within the directory, repacking the listing and shifting the later file contents to fill the created gap. The subsequent file appears instantly after that. The keyboard used by the Compucolor II was related through a ribbon cable via the 5501 parallel port. There was one other aspect which made the internal floppy drive on the Compucolor II troublesome. The lack of modulation on the info signal also made the drive quite delicate to the disk speed.

If the disk speed is off by a couple of %, particularly if the system which wrote the sector was different than the system studying it, bits could possibly be dropped or inserted. The rationale the memory mapped video deal with vary is duplicated is to permit a commerce-off between pace and high quality. Video was generated from a 4 KB reminiscence mapped region of the deal with house. In the traditional deal with range, the place the consumer is usually 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 does not have to entry RAM. When studying a sector, the software discards the primary few few bytes is might learn till it sees the 0x5A sync byte. Each of the 2K characters was represented by two bytes: a character byte, and an attribute byte. Have you ever been a giant sufficient Marvel fan to call the character who has a twin brother named Pietro, can use magic to alter reality and falls in love with Vision? Have you learnt the Marvel mutant who also makes use of both taking part in cards and a employees as weapons?