Intel386EX microprocessor aimed three major market segments: chan

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

Intel386EX microprocessor aimed three major market segments: chan

Datasheet Thumbnail

Top Searches for this datasheet

Intel386EX Microprocessor's Enhanced Compatibility
Intel386EX microprocessor aimed three major market segments:
channels have used very specific manner. embedded systems, common have memory-mapped devices transferring data between these devices memory would easy. QFD1 process determine customer requirements Intel386 microprocessor revealed above limitations totally unacceptable embedded control customers. Also, seven channels were deemed redundant.
those require compatibility development native environment, those require architecture compatibility able only develop debug environment also off-the-shelf software conjunction with their application, customer base looking upgrade path 80C186 designs.
Intel386EX Microprocessor's
Intel386 microprocessor employs block that eliminates above restrictions providing independent channels, each capable transferring data between combination memory devices. address registers byte count registers expanded support larger memory space. Other added features include buffer chaining, programmable priority levels, byte assembly. Details about enhanced features Intel386 microprocessor's will become available future date, this discussion will limited compatibility issues only. While providing above enhancements, developers have made careful efforts avoid incompatibility with PC/DOS standard follows:
addition fully static, modular Intel386 core, many peripheral functions Intel386 microprocessor enhanced Direct Memory Access (DMA) module. view above market segments, architectural task force strike delicate balance between providing embedded control customers performance they require ensuring that module interface remain compatible. This article explains "why chose what chose" regarding block.
8237A Limitations
PC-AT compatible architecture (defined ISA) incorporates 8237A controllers connected cascaded fashion. these controllers allows 8-bit transfers, while other allows 16-bit transfers through address shifting. all, seven channels available. However, there major restrictions this unit:
extensive study enhanced units available various chip sets (some them fully backward compatible some not) performed features that could incompatible were removed modified. example, even though Intel386 microprocessor's capable generating 26-bit addresses directly, option prevent overflow from lower bits higher bits will provided emulate page register 8237A. 8237A's operating modes supported (one exception explained later). Also, similar 8237A, Intel386 microprocessor's controller programmed through 8-bit registers.
8237A only 16-bit addressing capability. Hence, embedded processor like Intel386 microprocessor, with 26-bit Mbyte) addressing scheme, page register used allow address extension. This cumbersome affect performance. 8237A does have two-cycle data transfer mode allow memory-to-memory transfers channel. accomplish predefined
Quality Function Deployment (QFD) process systematic approach determine deploy available resources provide product characteristics that customers value most.
Even with such conscious effort maintain 8237A compatibility, must understood that Intel386 microprocessor's exactly 8237A. following section describes situations that require full compatibility with 8237A explain those could resolved Intel386 microprocessor-based system.
elegant desirable, could argued that some isolated applications that particular feature 8237A fail while running Intel386 microprocessor-based system. following explains this does pose problem. 8237A, channels must used perform memory-to-memory transfers cycles. earlier PC-XT, channel used memory refresh. subsequent PC-AT does refresh, backward compatibility, channel re-assigned made available perform other functions. Also, channel second 8237A (added 16-bit transfers PC-AT) used cascading. Thus, none 8237A could actually used two-cycle transfers PC-AT architecture. This renders incompatibility Intel386 microprocessor's with this feature non-issue. Finally, despite above arguments, when 8237A required application design, Intel386 microprocessor offers elegant solution. Intel386 microprocessor employs special address decoding scheme that "hides" registers non-DOS peripherals (e.g., chip selects, watchdog timer, etc.) from address range decoding scheme that PC-AT architecture uses. on-chip remapped space hidden this expanded space. external 8237A could occupy ISA-defined addresses provide desired PC-AT compatible functions.
Compatibility Ease Development
would easier talk about (PC-AT) compatibility from viewpoint first types market segments discussed beginning. Take case user whose main requirement able develop debug significant portion application platform. course, when transferred embedded target system, timings will different, functionality application could checked out. First all, does directly function calls. basic PC-AT functionality, used only floppy disk accesses through BIOS. customized BIOS planned Intel386 microprocessor) would provide transparent solution similar usage. This, course, assumes development "well-behaved" application that does access directly floppy disk transfers. Second, consider development application that accesses other application-specific through bus. channels offered Intel386 microprocessor, this should problem, 8237A registers, register addresses, programming operating modes maintained subset Intel386 microprocessor's DMA. follows that enhanced features Intel386 microprocessor could tested development system.
Conclusion
8237A controller does offer features performance demanded embedded control applications. controller module Intel386 microprocessor meets these performance requirements same time satisfies need PC-AT architecture compatible order serve target market segments requiring compatibility ease development PC-AT architecture compatibility able off-the-shelf software.
Compatibility Off-the-Shelf Applications
most stringent requirements compatibility will demanded application design employing off-the-shelf application utilizing channels (e.g., sound card) subsystems. mentioned above, Intel386 microprocessor's maintains compatibility with 8237A respects one: absence contrived two-cycle transfer mode. Although Intel386 microprocessor implementation more

Intel386EX microprocessor aimed three major market segments: chan

Top Searches for this datasheet

Other recent searches