Abstract:
A digital computer system having a socket capable of accepting any one of a family of processors, the family being defined as those processors having commonality of their respective basic input/output system code. Each processor has assigned pins for conducting specified signals, the pins engaging the socket. There is dissimilarity between at least two of the processors of correspondence where at least one of the specified signals, of one of the processors, is assigned to a different pin from the other processors. When such dissimilarity is present, the signal is redirected to the appropriate designated pin for the particular type of processor.

Description:
This is a Continuation of application Ser. No. 08/538,676, filed Oct. 2, 1995, now abandoned, which is a continuation of application Ser. No. 07/766,877, filed Sep. 27, 1991, now abandoned. 
    
    
     BACK OF THE INVENTION 
     1. Field of the Invention 
     This invention deals with a digital computer system having a processor socket capable of accepting any one of a family of processors. More particularly, this invention enables automatically accommodating the various processors in the family. 
     2. Description of the Related Art 
     Processors in a family of processors often differ in the assignment of a specified signal to a designated pin. That is, a pin on one of the processors may carry a particular specified signal while the corresponding pin on another of the processors carries a different specified signal. 
     In the past, it has been common practice to adjust the socket manually for each one of the processors. A jumper wire is placed from one location to another to redirect the particular signal to its assigned pin. 
     Other prior art solutions to the problem have involved switches that are set to redirect the signal from one pin to another of a particular processor. 
     Another solution to the problem includes using more than one socket. That is, a socket may be exclusively wired to receive one processor from the family of processors, with a second and third socket wired to accept others of the family. Such a system may include automatically switching those processors in place out of the circuit upon the installation of the last of the processors. 
     This invention enables the user to simply insert the desired processor from the family of processors into a single socket without concern for installing jumpers or throwing switches. The operation is completely transparent to him. 
     BRIEF SUMMARY OF THE INVENTION 
     A digital computer system has a socket capable of accepting any one of a plurality of types of processors having assigned pins for conducting specified signals and for engaging the socket. The processors have a common basic input/output system code and dissimilarity between at least two of the processors of correspondence between at least one of the specified signals and the assigned pins. The Intel Corporation processor types 80486DX, 80486SX and 80487SX, are the processors of the family in this preferred embodiment. Other processors of other families could, of course, be used. 
     The basic input/output system memory (BIOS) has a program for reading the type of processor, coding the type and storing the code in a register. The BIOS also has a program for detecting the presence or absence of a coprocessor, coding the presence or absence, and storing the code in the register. 
     A Programmable Array of Logic (PAL) is interposed between the register and the socket. The PAL is connected to certain of the pins and, depending upon the contents stored in the register, reroutes signals to other pins. A gate is used to completely block a signal from entry to the processor, depending upon the contents of the register. 
     The principle object of this invention is to provide a socket in a computer system that will automatically accept any one of a plurality of types of processors having assigned pins for conducting specified signals and having a common basic input/output system code, irrespective of dissimilarities between specified signals and assigned pins. This and other objects will be made evident in the detailed description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of the socket of this invention. 
     FIG. 2 is a block diagram of the processor, PAL and associated components. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention enables a user to interchange any one of a family of processors by simply inserting the processor into a socket. The user does not have to insert any jumpers or throw any switches. Any changes required in the processor socket because of dissimilarity of correspondence between specified signals and assigned pins is completely transparent to the user. The following description details the system used to obtain this result. 
     FIGS. 1A, 1B, 1C, and 1D, collectively referred to as FIG. 1, show socket 10 with terminal 26 carrying signal IGNNE * , terminal 27 carrying signal FERR1 * , terminal 29 carrying signal FERR * , and terminal 21 carrying signal NMI. Signals PRO/COP *  and DX *  /SX are combined in AND gate 11 to gate signal NMI through buffer 12. The &#34; *  &#34; is used to denote assertion of a low signal level. 
     FIG. 2 illustrates socket 10 with the necessary circuitry for enabling the redirection of specified signals to different pins, depending upon the type of processor used. 
     PAL 18 is shown having output IGNNE *  /NMI connected to pin a15 of processor 20. Pins c14 and a13 carries signals FERR *  or FERR1 * , respectively, to PAL 18. PAL 18, in this preferred embodiment, is a type 16R4-7. PAL 18 redirects signal FERR *  (and FERR1 * , as designated for the type 80487SX) when required. 
     In this preferred embodiment, only signals NMI, and IGNNE *  are required to be redirected. One of signals FERR *  and FERR1 *  is selected depending upon the type of processor. The following table illustrates the map for these signals. 
     
                       TABLE 1______________________________________Comparative Pin Differences     Pin NumbersSymbol      80486DX     80486SX  80487SX______________________________________FERR*       C14         NC       A13IGNNE*      A15         NC       A15NMI         B15         A15      B15NC: No Connect______________________________________ 
    
     BIOS 15 of any of the processors includes a program for detecting the processor type when the computer system first powers up. The ID is provided by the processor itself and the program supplied by the BIOS 15 codes that ID into a two bit binary code and stores it in register 16. BIOS 15 also has a program for detecting the presence or absence of a coprocessor, thereby adding to the identification of the processor. This information is coded into one bit in register 16 and is shown as signal PRO/COP * . The ID is shown as signal DX *  /SX from BIOS 15 into register 16. Programs written in assembly language source code for determining this identification are listed below. 
     
         __________________________________________________________________________configure.sub.-- processor.sub.-- type:shld     eax,edx,24     ;processor rev ID in AH; DX/SX processor #ype check -; if rev ID matches that of 486SX then SX else assume DXmov      a1,PORT.sub.-- XXHIGH.sub.-- INIT.sub.-- VALand      ah,11110000b   ;Mask off minor revision numbercrip     ah,i486SX.sub.-- REV.sub.-- ID                   ;If CPU rev not same as 486SX/487SXje       its.sub.-- an.sub.-- sxor       al;10000000b   ;Then set to DX processorand      al,not 01000000bcmp      ah,i486.sub.-- P23T.sub.-- REV.sub.-- IDje       its.sub.-- P23T.sub.-- F24                   ;P23T and P24mov      ah,aljmp      finish.sub.-- cpu.sub.-- pin.sub.-- setupits.sub.-- P23T.sub.-- P24:out      PORT.sub.-- XXHIGH,almov      ah,al          ;Save PORT.sub.-- XXHIGHout      MATHBSY,alfninitfldcw    cs:unmasked.sub.-- error.sub.-- cwfstp     st(0)          ;Force an FP errorfnstsw   word ptr cs:(0)WAFORIOWAFORIOmov      al,10b         ;Read IRRout      0a0h,alin       al,0a0hout      MATHBSY,al     ;Clear the pending errorfninitfldcw    cs:normal.sub.-- cwtest     al,20h         ;Check furry partjnz      finish.sub.-- cpu.sub.-- pin.sub.-- setup                   ;If error, P-24 - already doneor       ah,01000000band      ah,not 10000000bjmp      finish.sub.-- cpu.sub.-- in.sub.-- setupunmasked.sub.-- error.sub.-- cw        dw   0340hnormal.sub.-- cw        dw   037fhits.sub.-- an.sub.-- sx:and      ai,00111111b   ;Else it is SX. Now see if 486 or 487; Coprocessor presence determination; 1. Write to a memory location,; 2. reset FPU,; 3. store FPU&#39;s control word in the same memory location,; 4. if FPU is present the memory location contents will have;   changed (to the FPU&#39;s control word).; Note - Since no RAM has been established yet, we use the cache memory    under the ROM.mov      ebx,cr0or       ebx160000000h  ;Force 466 cache offmov      cr01ebxinvdtry.sub.-- cpu.sub.-- guess.sub.-- again:             ;Do not change any code after this label,             ,unless you truly understand the different             ,ways we may get here.and      a1,not PORT.sub.-- XX.sub.-- LOAD.sub.-- RAM.sub.-- M                       ;Turn on cache program modeor       al,20hlidt     cs:cpu.sub.-- guess.sub.-- tabout      PORT.sub.-- XXHIGH,al    ;Address bit 3 - 1 means writable    ;Address bit 2 - 1 means not cachablemov      bx, 0F000hmov      ds, bxxor      bx, bxmov      cx,1*4         ;F block, 16K or 32K units (note                   ;that for 32k units cx=2 is enough,                   ;but 4 works for 16k as well as 32k)align    16cache.sub.-- 466.sub.-- init.sub.-- loop.sub.-- coproc:mov      dx, dg: bx!+0100b                   ;writable, cachableadd      bx, 4000hdec      cxjnz      cache.sub.-- 486.sub.-- init.sub.-- loop.sub.-- coprocand      al,not 20hout      PORT.sub.-- XXHIGH,alor       al,PORT.sub.-- XX.sub.-- LOAD.sub.-- RAM.sub.-- M                   ;Turn off cache program modeout      PORT.sub.-- XXHIGH,almov      ebx,cr0and      ebx,not 60000000h                   ;Turn 486 cache onmov      cro,ebxmov      bx,ds: 0h!     ,read to get loc 0 into cachemov      word ptr ds: 0!,0ffffh                   ;write -1 to itfninit                  ,reset FPUfnstcw   ds:  0h!       ,store FPU control word in loc 0cmp      word ptr dg: 0!,0ffffhje       its.sub.-- Not.sub.-- A.sub.-- 487                   ;if memory changed (FPU found)                   ,then set pro/cop pin to coprocessoror       al,01000000bmov      ah,aljmp      short finish.sub.-- cpu.sub.-- in.sub.-- setupits.sub.-- Not.sub.-- A.sub.-- 487:                   ;here set pro/cop pin to processorand      al,00111111bmov      ah,alfinish.sub.-- cpu.sub.-- in.sub.-- setup:             ;Do not change any code atter this label,             ;unless you truly understand the different             ;ways we may get here.lidt     cg:cpu.sub.-- set.sub.-- tabmov      al,ahout      PORT.sub.-- XXHIGH,al__________________________________________________________________________ 
    
     The NMI signal for types 80486DX and 80487SX are applied to pin B15 through buffer 12 by the gating signal from register 16, as shown. If, however, the processor is type 80486SX, then signal NMI is applied to pin A15 via PAL 18, as shown. Signal IGNNE *  is applied to pin A15 for types 80486DX and 80487SX and not connected for the type 80486SX. The operation of PAL 18 is described by the following: 
     
         __________________________________________________________________________/** Inputs **/Pin 1 = palclk2         ;/* processor clock out of the clock chip                             */Pin 2 = oscclk2         ;/* copy of the above clock                             */Pin 3 = ferr.sub.--         ;/* 486DX FERR*     */Pin 4 = ferr1.sub.--         ;/* 487SX FERR*     */Pin 5 = pro.sub.-- cop         ;/* 1 - using a 486SX, 0 - using a 487SX                             */Pin 6 = dx.sub.-- sx         ;/* 1 - using a DX, 0 - using an SX                             */Pin 7 = resnpx         ;/* not used anymore                             */Pin 8 = bsy386.sub.--         ;/* signal to processor that coproc is busy                             */Pin 9 = |oe.sub.--         ;/* testability pin. oe.sub.--  = 0 is enabled                             */Pin 11 = |roe.sub.--         ;/* testability pin for registered outputs                             */Pin 12 = nmi   ;/* NMI from the system                             *//** Outputs **/Pin 13 = errnpx.sub.--         ;/* coprocessor error to the 330                             */Pin 14 = ignne.sub.--         ;/*                 */Pin 15 = ferrd.sub.--         ;/* ferr* delayed by one clock                             */Pin 16 = bsynpx.sub.--         ;/* coprocessor busy                             */Pin 17 = clk2by2         ;/* processor clock divided by 2                             */Pin 18 = clk2syn         ;/* aligned CLK2    */Pin 19 = |clksyn         ;/* aligned CLK1    *//** Logic Equations **/clk2by2.d = |clk2by2 ;clksyn  = | oscclk2 &amp; clk2by2                 /* Take skew out of clk2 and clk1 by */   # clksyn &amp; clk2by2                 /* making sure both clocks are generate   # clksyn &amp; oscclk2 ;               /* off of the same edge */clk2syn = |oscclk2 ;errnpx.sub.--   = bsynpx.sub.-- ;$define s0     &#39;b&#39;111$define s1     &#39;b&#39;001$define s2     &#39;b&#39;011$define s3     &#39;b&#39;010$define s4     &#39;b&#39;110$define s5     &#39;b&#39;000$define s6     &#39;b&#39;100$define s7     &#39;b&#39;101FIELD   npxerr =  ferrd.sub.--, bsynpx.sub.--, ignne.sub.-- !;SEQUENCE   npxerr {present    s0if |nmi &amp; pro.sub.-- cop &amp; |dx.sub.-- sx next s4 ;  /* 486SX nmi steering*/if |ferr.sub.--  &amp; dx.sub.-- sx next s1 ;if |ferr1.sub.--  &amp; |dx.sub.-- sx &amp; |pro.sub.-- cop next s1 ;default next s0 ;present    s1if ferr.sub.--  &amp; dx.sub.-- sx next s0 ;                 /* return if error went away */if ferr1.sub.--  &amp; |dx.sub.-- sx &amp; |pro.sub.-- cop next s0 ;if pro.sub.-- cop &amp; |dx.sub.-- sx next s4 ;                 /* if 486SX, route to S4 */default next s2 ;present    s2if bsy386.sub.-- next s3 ;         /* goes not busy when portF0 written toif ferr.sub.--  &amp; dx.sub.-- sx next s0 ;if ferr1.sub.--  &amp; |dx sx &amp; |pro.sub.-- cop next s0 ;if pro.sub.-- cop &amp; |dx.sub.-- sx next s4 ;default next s2 ;present    s3if ferr.sub.--  &amp; dx.sub.-- sx next s0 ;if ferr1.sub.--  &amp; |dx.sub.-- sx &amp; |pro.sub.-- cop next s0 ;if pro.sub.-- cop &amp; |dx.sub.-- sx next s4 ;default next s3 ;present    s4if nmi &amp; pro.sub.-- cop &amp; |dx.sub.-- sx next s0 ;                 /* wait for 486SX nmi */if dx.sub.-- sx next s0 ;if |dx.sub.-- sx &amp; |pro.sub.-- cop next s0 ;default next s4 ;present    s5next s0 ;present    s6next s0 ;present    s7next s0 ;clksyn.oe = oe.sub.--  ;clk2syn.oe     = oe.sub.--  ;errnpx.sub.--.oe     = oe.sub.-- !;__________________________________________________________________________ 
    
     MODE OF OPERATION 
     Assume that a type 80486SX processor is installed in the socket 10. In that case, signal NMI is blocked by gate 12 from pin B15 of socket 10. Signal NMI is redirected through PAL 18 to pin A15, the correct pin as indicated in table 1. That is the only redirection required in that instance. When a type 80487SX processor is installed, the NMI signal is gated through buffer 12 to pin B15 of socket 10. Signal IGNNE *  is gated by the PAL to pin A15. Pin A13 is scanned for its indication of signal FERRI * . 
     When a type 80486DX processor is installed, signal NMI is gated through buffer 12 and impressed on pin B15. Signal IGNNE *  is gated by the PAL to Pin A15. Pin C14 is scanned for its indication of signal FERR * . In this manner, it is shown that at least three different processors from the same family may each be installed in a single socket without the user having to take any further steps or precautions. 
     The above-described arrangement is merely an illustrative application of the principles of the invention; numerous other arrangements may be devised by those skilled in the art without departing from the skill and scope of the invention which is limited only as defined by the appended claims.