TF536 and CDTV's cd drive

68030 + SDRAM + IDE

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terriblefire
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Re: TF536 and CDTV's cd drive

Post by terriblefire »

If you need me to get a CDTV set up and track down whats going on in any particular case I can do that too. Got quite a few projects in flight right now though.
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Re: TF536 and CDTV's cd drive

Post by CaptFuture »

Thx a lot for the offer! Right now I am only aware of one issue, but it’s not really urgent atm. The first 16K of the Extended ROM space on the TF536 are mapped to a piece of boot code, which makes the underlying first 16K of CDTV OS ROM inaccessible. It’s not really a blocking issue atm, because I’ve worked around it by simply moving all vital resident modules out of that 16K area in my ROM builds for now.

IIRC dalek did report an issue with CD ROM access when he booted his CDTV+TF536 from IDE, but I have no clue yet what could be causing that. I would really like to reproduce that issue on my own TF536 and do some debugging first to narrow down the root cause as far as I can before calling on you. Thx again for the generous offer, really appreciated! I will report my progress on the TF536 in this thread once that ball starts rolling. :thumbup:
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Re: TF536 and CDTV's cd drive

Post by terriblefire »

CaptFuture wrote: Thu Sep 09, 2021 5:39 am Thx a lot for the offer! Right now I am only aware of one issue, but it’s not really urgent atm. The first 16K of the Extended ROM space on the TF536 are mapped to a piece of boot code, which makes the underlying first 16K of CDTV OS ROM inaccessible. It’s not really a blocking issue atm, because I’ve worked around it by simply moving all vital resident modules out of that 16K area in my ROM builds for now.

IIRC dalek did report an issue with CD ROM access when he booted his CDTV+TF536 from IDE, but I have no clue yet what could be causing that. I would really like to reproduce that issue on my own TF536 and do some debugging first to narrow down the root cause as far as I can before calling on you. Thx again for the generous offer, really appreciated! I will report my progress on the TF536 in this thread once that ball starts rolling. :thumbup:
I could make a firmware update to remove that or tighten it down to 128 bytes.
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Re: TF536 and CDTV's cd drive

Post by CaptFuture »

That would be great. Either option would be fine. A bit of context:

The first 128 bytes will only overlap the CDTV-specific exec module that’s at F00000. Any exec version in the F80000-FFFFFF Kickstart ROM space will always pass control to the CDTV specific exec very early in the boot process, but at some point the CDTV specific exec will pass control back to the exec in the Kickstart ROM if that is a higher version. I haven’t disassembled/traced enough of exec to tell at what point this occurs exactly.

I am only aware of two differences between the CDTV exec and “normal” exec modules that come in Kickstart ROMs:

1) The CDTV exec also scans the E00000-E7FFFF address range for any resident modules. This is where the CDTV RAM cards are mapped and this allows you to put resident modules on RAM cards and have them auto-initialized at boot. This functionality would be lost if anything else, no matter how small, is mapped at F00000. However, I might be able to ditch the CDTV specific exec module altogether in a future release and patch this lost functionality back in somehow (and freeing up a lot of much needed ROM space in the process!)

2) It disables Guru messages and instead goes straight to reboot. This was deliberately disabled because it was judged that CDTV end users would be your average Joe Consumer types and not computer users, so a Guru would be meaningless and confusing in an appliance like CDTV. However, it seems the Gurus are re-enabled anyway when a higher version Exec in the Kickstart ROM takes over, so no loss there.
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Re: TF536 and CDTV's cd drive

Post by terriblefire »

There are a couple of options.

1. disable the rom completely... its non-functional. Its only purpose is to give a good indication to builders that things have worked.

2. Put the rom somewhere else? (is there anywhere safe).

3. Make the rom an Autoconfig ROM... (more complex and overkill... probably better to do 1 instead).

On the CD32 the 0xF00000 expansion area is mirrored elsewhere so this isnt an issue.
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Re: TF536 and CDTV's cd drive

Post by CaptFuture »

Hate to be the one to make life harder for the builders, but I’m afraid this leaves option 1 as the only viable solution. I agree that option 3 is overkill and time better spent on other things, and I don’t know of any other place to put the TF536 boot code on CDTV and have it automatically run at boot. The Exec in the Kickstart ROM just looks for the magic value $1111 at F00000 and if found jumps to F00002.
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Re: TF536 and CDTV's cd drive

Post by dalek »

Can the flashy rom just set a flag for the rom decoder to disable itself after it has first run, then finally jump back to $F00000 as if it were never there ? (or do the same and jump to $F00002 if it is there)
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Re: TF536 and CDTV's cd drive

Post by dalek »

CaptFuture wrote: Thu Sep 09, 2021 5:39 am ...
IIRC dalek did report an issue with CD ROM access when he booted his CDTV+TF536 from IDE, but I have no clue yet what could be causing that.
...
CaptFuture fixed this in his most recent build :D

I also have a 90° relocator in the works that adds a socket for a single 27C400 extended ROM like the A570 so you don't have to find 2x 27C1000's and can use e.g. cmorely's eprom emulator. I just ballsed up one connection so am fixing that in a new rev, will be waiting for new pcbs then will release all the kicad files once tested.

Height is still an issue and really requires soldering the TF536 to the relocator without a socket and soldering the 030 without a socket as well. But it will also work for e.g. the "030-TK".

Who knows one day someone may relayout the TF536 as a CDTV specific version not requiring a relocator and incorporating the single eprom mod (hint hint TF - TFTV ;) )
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Re: TF536 and CDTV's cd drive

Post by terriblefire »

dalek wrote: Thu Sep 09, 2021 1:53 pm Can the flashy rom just set a flag for the rom decoder to disable itself after it has first run, then finally jump back to $F00000 as if it were never there ? (or do the same and jump to $F00002 if it is there)
This is way to complicated. When things are complicated they break more easily.

Instead... have 2 firmwares. Use the A500 when building. CDTV Firmware when using on a CDTV.. Anything else is just asking for trouble.

Try this firmware. I've not tested it but all i've done is braindamage out the rom decode.
tf536r2_main_top_CDTV_FULL_PHASE_7.zip
(18.87 KiB) Downloaded 152 times
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Re: TF536 and CDTV's cd drive

Post by dalek »

terriblefire wrote: Sun Sep 12, 2021 11:35 am Try this firmware. I've not tested it but all i've done is braindamage out the rom decode.
tf536r2_main_top_CDTV_FULL_PHASE_7.zip
Cool, that sounds good.

Would love to try, except I'm "that guy" that only has a r1 :roll:
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