RS-232 port to ZX-SPECTRUM. Here is an article telling you about the essence and significance of the new ferrum-project - RS-232 port to ZX-SPECTRUM. Author of the idea and the one who put her into iron is your humble servant (Artem or Pink Panther). At the moment I can only collect two copies of this lotion. The reason is that there are only two RS-232 port controller IC (WD8250). HELP ME!!!!! Possess these microcircuits, as well as the computers in which they are installed updated (EC 1843, etc.), do not let the project go down the drain beginning of its existence - sell (or give away) these chips for me (or anyone who wants to build this controller). As you know, using the RS-232 interface (in simple Rodier COM port or serial port) connect the widest range of peripheral devices. Among them are modems, mice, scanners, printers, computers (for data exchange) and etc. etc. The development we bring to your attention is intended primarily for connecting a modem (HAYES) or other computer (even IBM PC). About the advantages and benefits I won’t tell you about PC modems before homemade products. Oh a wonderful opportunity to connect computers via a null modem I'll tell you more. If there are a couple of computers in front of you and you needs to be rewritten from one tothe other is something voluminous, and fussing with floppy disks doesn’t suit you, then a null modem is what you need. Transfer speed - up to 56 Kbaud or almost 6 kb/sec. And error control by parity (even - odd) is sufficient is definitely reliable and capable of ensuring the integrity of your data. At the moment (08/27/99) the schematic diagram is ready ma, awaiting its incarnation in iron. The controller will assembled on six ICs (one LSI - 40 contacts and 5 14 legs each). The controller will be connected to the system connector (using van 21 contacts). In connection with this, the question of tire overload arises - a progressive user will have controls hanging on the bus controllers - mouse, hard drive, RS-232 port - overload and obvious There are difficulties with connection. So next, fer- The rum project should be a bus buffer-extender (it should have but at least three expansion connectors will appear). An important point (among the advantages of the scheme) is the no need for negative voltages (-5 and -12 V). And briefly about the abilities and capabilities of the controller. * Designed for the easiest connection to the most widely used microprocessors (Z-80, 8080A, 6800 etc.). * Full double buffering. * Independent control of transmission, reception, lines state, interruption. * Programmable oscillatortransmission speed allows divide any input clock pulses by a number from 1 to (2**16-1) and produces internal sixteen-fold synchronization. * Independent input of receiver clock pulses. * Fully programmable serial interface. Specifications: - 5, 6, 7 or 8 bit data; - formation of a parity or odd parity bit and its detection; - formation of 1, 1.5 or 2 stop bits; - formation of baud rate (communication channel with speed up to 56 Kbaud); - detection of a false start bit; * Complete status message specifications * 3-state TTL driver for bidirectional bus data and control bus. * Generate and detect transmission interruption. * Internal diagnostic characteristics - monitoring the communication line to detect faulty insulation. - modeling of transmission interruption errors, parity, overflow, cropping. * Fully controlled priority interrupt system. * Single power supply +5 V. An important feature of this particular development is FOR THE FIRST TIME, a peripheral operating system implemented on the Spectrum devices on interruption. A similar system is used on all serious machines (for devices that do not use DMA). New will be the full implementation of the regimeIM2 interrupts. As is known, in this mode the processor can service up to 128 devices on one interrupt (!!! Important difference from IBM PC.), using an interrupt vector of 256 bytes in size (two bytes per device). But only one thing is implemented in the Spectrum interrupt - timer with a frequency of 5 OHz. On machines with stable bus (Scorpion type) this is the last interruption (128th) in the century - interrupt tore. The RS-232 interface controller will be used Issue one of the remaining 127 free interrupts. Such a system the theme will be able to work even under IS-DOS with its resident system on a timer interrupt. If you have a question why this is needed, I will explain: system the topic of working with interruptions frees up the programmer's hands - os- frees you from having to cycle through the “ready-not-ready” polling cycle tovo" and allows you to administer data directly during reception and transmission. On this optimistic note, let me end the first my article about RS-232 INTERFACE CONTROLLER. Everyone will be interested bathrooms and those interested in hardware and software and support of this project, with all wishes and questions please contact me - ask MSD-Group on the Radio Market Artem (I will be glad to listen to all requests). 08.27.99 22:15 Pink Panther.
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