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Edstrom #105640 05/18/16 09:31 PM
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Cool, these are real computers! :))


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Edstrom #105965 06/08/16 01:51 PM
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Slight progress with the Force CPU-30 driver.

The new DUSCC serial device I am working on let some characters out of it! The DUSCC is really much more complex than the SCC but much less successful. Hopefully there are other boards using this chip out there.

I have also improved the 68230 device and added a FGA-002 gate array skeleton device. I'll submit it as soon as I get input to work also.



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Edstrom #105967 06/08/16 03:29 PM
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The docs for the MVME6000 bus controller used on the MVME147 is up on bitsavers now.

Edstrom #105970 06/09/16 10:52 AM
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I found out that there are DUSCC designs from Force Computers and some models from DEC, a microserver and a DECrouter-150/-250.

I got the ISIO-1 firmware which includes DUSCC diagnostics(!) so I will hook it up to test the DUSCC implementation.

I have nothing on the DEC stuff yet. VME interfaces are next.


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Edstrom #105996 06/10/16 10:49 PM
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Hmm, I just added the official ROM:s for the ISCSI-1 VME board and they look very similar to the ROM:s from the Besta 88 computer smile



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Edstrom #106008 06/11/16 03:13 PM
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Compare the mc7105 to the vt240 and you'll see the same thing.

Edstrom #106009 06/11/16 04:26 PM
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Hah, that's pretty funny. I guess the CPU wasn't the only thing they cloned smile

Edstrom #106025 06/13/16 10:23 AM
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Yeah, peripherals and software too were cloned. There's a interesting document (circa 1983) on experience gained from working with IBM System/360 clones (the ES EVM series) -- http://tapemark.narod.ru/cejtin.html -- Google does a nice job translating it.

Edstrom #106355 07/04/16 09:19 PM
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Is the 68030 cycle accurate enough for register to register calculations and DIV arithmetics? The Force CPU-30 firmware code below uses the timer to meassure the time it takes to execute some code to determine what CPU is on the board. Should it work? If so I need to fix the timer I just implemented.

Code:
FFE033C6: movem.l D1-D6/A5, -(A7)
FFE033CA: movec CACR, D2; (2+)
FFE033CE: move.l  D2, -(A7)
FFE033D0: moveq   #$0, D1
FFE033D2: movec D1, CACR; (2+) // Disable cache
FFE033D6: move    SR, D3
FFE033D8: move.l  D3, -(A7)
FFE033DA: move    #$2700, SR   // Disable all interrupts
FFE033DE: lea     $ff800e00.l, A5 // 68230 PIT base
FFE033E4: move.b  #$0, ($10,A5)  // TCR - timer disabled 
FFE033EA: move.b  #$ff, ($13,A5) // Preload Hi
FFE033F0: move.b  #$ff, ($14,A5) // Preload Mid
FFE033F6: move.b  #$ff, ($15,A5) // Preload Lo
FFE033FC: move.l  #$4e20, D0
FFE03402: move.l  #$3, D1
FFE03408: move.l  #$2, D2
FFE0340E: move.l  #$2, D3
FFE03414: move.b  #$1, ($10,A5) // Timer enabled
FFE0341A: move.l  D2, D4
FFE0341C: move.l  D3, D5
FFE0341E: move.l  D1, D6
FFE03420: divs.l  D6, D2:D3; (2+)
FFE03424: subq.l  #1, D0
FFE03426: bne     $ffe0341a // loop for $4e20 times
FFE0341A: move.l  D2, D4
FFE0341C: move.l  D3, D5
FFE0341E: move.l  D1, D6
FFE03420: divs.l  D6, D2:D3; (2+)
FFE03424: subq.l  #1, D0
FFE03426: bne     $ffe0341a // loop for $ffffffff times

   (loops for 119988 instructions)

FFE03428: move.b  #$0, ($10,A5) // disable timer
FFE0342E: moveq   #$0, D0
FFE03430: move.b  ($17,A5), D0 // counter register Hi
FFE03434: lsl.l   #8, D0
FFE03436: move.b  ($18,A5), D0 // counter register Mid
FFE0343A: lsl.l   #8, D0
FFE0343C: move.b  ($19,A5), D0 // counter register Low
FFE03440: not.l   D0
FFE03442: lsr.l   #4, D0
FFE03444: lea     ($22,PC), A5; ($ffe03468)
FFE03448: move.w  (A5)+, D1
FFE0344A: cmp.w   D1, D0     // Apparantly looking up timer result in table
FFE0344C: bhi     $ffe03454
FFE03450: addq.l  #2, A5
FFE03452: bra     $ffe03448
FFE03448: move.w  (A5)+, D1
FFE0344A: cmp.w   D1, D0
FFE0344C: bhi     $ffe03454
FFE03450: addq.l  #2, A5
FFE03452: bra     $ffe03448

EDIT: Apparantly this is only for the clock detection of the board and I am currently off by a factor two approximately but still outside the table and got the default which is 36MHz instead of 16MHz.. So I have probably missed a divider in the data sheet, but still not close enough..

Last edited by Edstrom; 07/04/16 10:23 PM.

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Edstrom #106367 07/05/16 10:50 PM
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The board is actually 25MHz, and after correcting that and trying to find the factor of error to get the right table entry, I find that a factor of 5 identifies a 20MHz board and a factor of 4 a 36MHz board, so it isn't just a simple divider or two that needs to be corrected.

I believe that the factor is 4, 2 from the counter and 2 from the prescaler, where I count both raising and falling edges currently, does that makes sense? However, if that is correct I am still off by some meassure. Here is the table:

As you can see the difference between the 25MHz I want to get and the 20MHz I get is only 0x200 shifted 4 so times 16 = 0x2000 which is far from the 20% I would expect. How does that work? Any hint in the right direction appreciated, even smaller insults.


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