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Re: Fairlight CMI [Re: SynaMax] #112971
03/28/18 12:57 AM
03/28/18 12:57 AM
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R. Belmont Offline
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You sure it's not switching CPUs at that point?

Re: Fairlight CMI [Re: SynaMax] #112973
03/28/18 01:37 AM
03/28/18 01:37 AM
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SynaMax Offline OP
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I just double checked and made sure I wasn't focused on CPU 1. When I hit either F10 or F11 to go to the next instruction, it stays on CPU1.

The only reference to 4FE2 I can find is here:

Code
8DB1: LDX   #$4FE2
8DB4: STX   $FFDE


EDIT: It's triggering an interrupt, I think. According to this site, FFDE-FFDF is IRQ15 (low priority PICU). $5025 is an RTI opcode and jumps back to $4FE2.

Last edited by SynaMax; 03/28/18 01:53 AM.
Re: Fairlight CMI [Re: SynaMax] #112977
03/28/18 12:48 PM
03/28/18 12:48 PM
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Ahh, yeah, IRQ is the other reason the PC will go flying.

Re: Fairlight CMI [Re: Lord Nightmare] #113292
04/29/18 01:48 PM
04/29/18 01:48 PM
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Lord Nightmare Offline
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Originally Posted by Lord Nightmare
There exist schematics for rev 8 of the voice cards at http://www.fairlightus.com/cmi/fairlight_docs/CMI-01.pdf and http://www.fairlightus.com/cmi/fairlight_docs/CMI-01A.pdf which, while they are later cards, may have enough of the PIA CAx and CBx connections to the 6840PTM chip the same to allow the driver to start to pass those tests.


These links are now dead, did someone save those two PDFs? archive.org did not grab them.

EDIT: Nevermind, archive.org did grab them, I just missed them (thanks, balrog!):
http://web.archive.org/web/20170801113735/http://www.fairlightus.com/cmi/fairlight_docs/CMI-01.pdf
http://web.archive.org/web/20170801113535/http://www.fairlightus.com/cmi/fairlight_docs/CMI-01A.pdf

More docs can be found at https://web.archive.org/web/*/http://www.fairlightus.com/cmi/fairlight_docs/*


LN

Last edited by Lord Nightmare; 04/29/18 03:08 PM. Reason: Add links

"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"
Re: Fairlight CMI [Re: Lord Nightmare] #113294
04/29/18 08:43 PM
04/29/18 08:43 PM
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SynaMax Offline OP
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Steve Rance also made a mirror of that site here:

http://steverance.com/CMI/

And here's the links to those PDFs as well, just in case.
http://steverance.com/CMI/fairlight_docs/CMI-01.pdf
http://steverance.com/CMI/fairlight_docs/CMI-01A.pdf

Last edited by SynaMax; 04/29/18 08:58 PM.
Re: Fairlight CMI [Re: SynaMax] #113299
04/30/18 11:13 AM
04/30/18 11:13 AM
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Lord Nightmare Offline
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The major differences between the CMI-01 and CMI-01A are mostly in the entirely different analog section.

The memory map is also slightly different:
Code
CMI-01:
00 - /PORT (read/write to RAM address at ram pointer location, may auto-increment?)
01 - /LVD write (VCA DAC)
02 - /LAT2 write (low 4 bits; to FILT filter circuit PWM (chopper? or pulse width?) generator)
03 - /FRD write
04 - /FRU write
05 - N/C
06 - N/C
07 - N/C

CMI-01A:
00 - /PORT (read/write to RAM address at ram pointer location, may auto-increment?)
01 - N/C
02 - N/C
03 - /FRD write
04 - /FRU write
05 - /LVOL write (VCA DAC)
06 - /LFILT write (8 bits, expanded to 10 bit DAC input and to FILTER input of SSM2045 VCF/VCA)
07 - N/C


The remainder of the PTM/PIA and RAM memory map is the same on both.
The O bus of the second PIA's port A affects the filter in a different way on the CMI-01A (it adds to the top 4 bits of the FILTER input to the SSM2045) vs affecting the PWM counter on the CMI-01.

LN


"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"
Re: Fairlight CMI [Re: Lord Nightmare] #113303
05/01/18 01:06 AM
05/01/18 01:06 AM
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SynaMax Offline OP
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Awesome find on the memory map differences, LN! I'm pretty sure CMI-01-A is the one we want to follow since that was the channel card used in the CMI IIx. I'm not sure if the CMI-01 is compatible with the Series IIx, since it originally was for the Series I.

I found out how the Fairlight writes to the channel cards. The subroutine starts at $5557 by loading the sample audio data into A by grabbing it from X and then increments X. In this case, the sample data was temporarily located at $8000 so X's value started at 8000. At $5559, it stores A at $E000, the channel card port and then the next instruction increments register B. It does this for 80 bytes and breaks the loop once B hits 80. Then the machine executes several other instructions before going back to load the next 80 bytes of the sample data.

Code
5557:    LDA   ,X+
5559:    STA   $E000
555C:    INCB
555D:    BPL   $5557

Last edited by SynaMax; 05/01/18 01:06 AM.
Re: Fairlight CMI [Re: SynaMax] #113415
05/12/18 07:02 PM
05/12/18 07:02 PM
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SynaMax Offline OP
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Just saw this on the Fairlight Facebook Group:

[Linked Image]

This photo was taken by Robbie Puricelli, a Fairlight restorer and I asked him a few questions. First off, as you can see in the photo above, it's possible to boot into the Fairlight's OS without channel cards installed; just boot off of the system disk like you normally would. Second, he told me Series I cards (aka the CMI-01) are compatible with the Series IIx.

Re: Fairlight CMI [Re: SynaMax] #113436
05/15/18 10:44 PM
05/15/18 10:44 PM
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SynaMax Offline OP
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Nothing technical, just a really cool video on why this machine is amazing (and further proof as to why it needs to be preserved).


Re: Fairlight CMI [Re: SynaMax] #113635
06/29/18 09:04 PM
06/29/18 09:04 PM
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SynaMax Offline OP
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Anyone want to buy a Fairlight?

It's currently broken but with the right parts and restoration efforts, it would be nice to have a unit on hand to debug with.

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