http://183.60.139.2/gdown_group3 ... le=KeilC51V9.00.zip

看了看详细说明，真是从v9.06跳到v9.50：

C51 Version 9.50 Release

Release Date: 12 June 2012

    [New Supported Devices]
        Cypress
        CY8C3244AXI-153, CY8C3244LTI-123, CY8C3244LTI-130, CY8C3244PVI-133, CY8C3245AXI-158, CY8C3245AXI-166, CY8C3245LTI-129, CY8C3245LTI-139, CY8C3245LTI-144, CY8C3245LTI-163, CY8C3245PVI-134, CY8C3245PVI-150, CY8C3246AXI-131, CY8C3246AXI-138, CY8C3246LTI-125, CY8C3246LTI-128, CY8C3246LTI-149, CY8C3246LTI-162, CY8C3246PVI-122, CY8C3246PVI-147, CY8C3444AXI-116, CY8C3444LTI-110, CY8C3444LTI-119, CY8C3444PVI-100, CY8C3445AXI-104, CY8C3445AXI-108, CY8C3445LTI-078, CY8C3445LTI-079, CY8C3445LTI-081, CY8C3445LTI-089, CY8C3445PVI-090, CY8C3445PVI-094, CY8C3446AXI-099, CY8C3446AXI-105, CY8C3446LTI-073, CY8C3446LTI-074, CY8C3446LTI-083, CY8C3446LTI-085, CY8C3446PVI-076, CY8C3446PVI-091, CY8C3446PVI-102, CY8C3665AXI-010, CY8C3665AXI-016, CY8C3665LTI-006, CY8C3665LTI-044, CY8C3665PVI-007, CY8C3665PVI-008, CY8C3665PVI-080, CY8C3666AXI-036, CY8C3666AXI-037, CY8C3666AXI-052, CY8C3666LTI-027, CY8C3666LTI-050, CY8C3865AXI-019, CY8C3865LTI-014, CY8C3865LTI-062, CY8C3865PVI-060, CY8C3865PVI-063, CY8C3866AXI-035, CY8C3866AXI-039, CY8C3866AXI-040, CY8C3866LTI-030, CY8C3866LTI-067, CY8C3866LTI-068, CY8C3866PVI-021, and CY8C3866PVI-070.
        Zilog
        Z51F0410, Z51F3220, Z51F3221, Z51F6412, and Z51F811.

    [µVision4]
        This C51 release comes with µVision V4.53.0.4 which includes the new Scintilla based editor.

        The new editor includes the following enhancements:
        Encoding for UTF-8 Unicode, DBCS Korean, DBCS Japanese, and DBCS Chinese languages. Unicode and Asian ANSI encoding is recognized automatically when a file is opened.
        Monospaced fonts and proportional fonts are supported.
        Syntax coloring has been extended.
        Unprintable characters, such as End-Of-Line, can be visualized in the editor.
        The Outlining menu has been simplified. Outlining information is saved and restored for each file.
        Search and replace utilities (Incremental Find, Find-in-Files, and Replace) have been reworked.
        Text can be zoomed with Ctrl+mouse wheel. The information is saved and restored for each file.
        In case device-specific books are not found in the local installation, then www.keil.com is scanned for a matching document.

        and corrections: Scrolling quickly through large files with Page Up or Page Down works smoothly.
        The editor's context menu can be closed by pressing ESC.
        Breakpoints can be set now with a simple click into the editor margin.
        Under some circumstances the Debugger showed wrong values of arrays or structures in the Watch window.

        Refer to Revision History for a complete list.

C51 Version 9.06 Release

Release Date: 15 February 2012

    [New Supported Devices]
        Atmel AT89LP51RB2, AT89LP51RC2, AT89LP51IC2, AT89LP51RD2, AT89LP51ED2, and AT89LP51ID2 devices.
        Infineon TLE9831, TLE9832, TLE9833, TLE9834, and TLE9835 devices.
        Maxim 71M6531D, 71M6531F, 71M6532D, 71M6532F, 71M6534H, 71M6541D, 71M6541F, 71M6542F, 71M6543F, and 71M6543G devices.
        Silabs C8051F969, C8051F968, C8051F967, C8051F966, C8051F965, C8051F964, C8051F963, C8051F962, C8051F961, C8051F960, Si1037, Si1036, Si1035, Si1034, Si1033, Si1032, Si1031, Si1030, Si1027, Si1026, Si1025, Si1024, Si1023, Si1022, Si1021, and Si1020 devices.
    [Device Support]
        Added: Quick_Test example for Infineon TLE983x based devices in folder ..C51ExamplesInfineon TLE983x.
        Added: banking example for Maxim 71M6543G device in folder ..C51ExamplesMaximBankEx1.
        Added: banking example for Maxim 71M6534H device in folder ..C51ExamplesMaximBankEx2.
    [µVision4]
        This C51 release comes with µVision V4.24.00.

应该会是增加mdk类似的一些功能吧

只要要按它的要求注册就可以下载的，下载后，使用注册·机 完美注册即可。