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KanedaFr
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Joined: 29 Aug 2006
Posts: 635
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 Posted: Tue Jul 19, 2011 9:49 pm Post subject: |
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I added my Magic Drive schematic on the SMD page.
Now working on the RAM boards  |
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Chilly Willy
Very interested
Joined: 17 Aug 2007
Posts: 1955
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| Posted: Wed Jul 20, 2011 3:29 am Post subject: |
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| I know it's a bit off topic, but if I had been making the SEGA CD, it would look just like the SMD. Look at an image of a SMD and tell me you don't think "CD" right off the bat. Have it flip open right in the middle with the circuit board above the CD with the cart slot attached so it's right where the cart slot in the SMD is. Plugging in the cart slot would have made the CD more flexible and given the chance to put a simple 256 color framebuffer in it for improved graphics. |
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TascoDLX
Very interested
Joined: 06 Feb 2007
Posts: 215
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| Posted: Wed Jul 20, 2011 7:06 am Post subject: |
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Yes, my immediate thought looking at the SMD is Jaguar CD. Is that it?
I don't care to be the one to second-guess the Sega CD. But with a framebuffer and improved color depth, it would have been quite intriguing -- a whole different ballgame, even. It's a nice fantasy. That said, I kinda enjoy the system for what it is. |
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Chilly Willy
Very interested
Joined: 17 Aug 2007
Posts: 1955
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| Posted: Wed Jul 20, 2011 11:09 pm Post subject: |
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| TascoDLX wrote: | | Yes, my immediate thought looking at the SMD is Jaguar CD. Is that it? |
Exactly. You can't look at the SMD and not think it... well, in my opinion, at least. I think it looks cooler than either the model 1 or 2 CD as well.
| Quote: | | I don't care to be the one to second-guess the Sega CD. But with a framebuffer and improved color depth, it would have been quite intriguing -- a whole different ballgame, even. It's a nice fantasy. That said, I kinda enjoy the system for what it is. |
I don't think the extra 68000 was really needed - just ram for the MD CPU to use for programs/data loaded from CD, and the ASIC/framebuffer. Kinda on the fence about the PCM chip. They could have left it out if they wished to keep the price down. I think SEGA only added it because the PCE CD had an ADPCM chip in it. |
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Koji
Interested
Joined: 13 Apr 2011
Posts: 11
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| Posted: Sat Jan 07, 2012 8:26 pm Post subject: |
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Quick question, is there a SMDutil for dummies? ("how to")..I ask because I just can't seem to be able to make it work with my Super Magic Drive parallel port at all...
I'd like to dump the SMD "Magic Driver V-1" bios that I have, with it... |
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KanedaFr
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Joined: 29 Aug 2006
Posts: 635
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| Posted: Sun Jan 08, 2012 7:42 am Post subject: |
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| did you try with ucon64 ? |
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Koji
Interested
Joined: 13 Apr 2011
Posts: 11
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| Posted: Sun Jan 08, 2012 7:57 am Post subject: |
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Not yet, but I must be doing something wrong though..How do I go at installing something like io.dll (on windows xp) for example?...
I just figured SMDutil is the way to go when it comes to the SMD no?.. |
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KanedaFr
Administrateur
Joined: 29 Aug 2006
Posts: 635
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| Posted: Sun Jan 08, 2012 2:56 pm Post subject: |
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I stopped fighting with LPT port on windows , I use a linux just for this.
Else, look at ucon64 page, there is a LPT driver for windows which I remember I used before
(http://ucon64.sourceforge.net/) and I think you should be able to get info from their faq
If you succeed, don't forget to send it to me so I can disassemble it  |
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greatfunky
Newbie
Joined: 31 Oct 2011
Posts: 4
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| Posted: Fri Feb 03, 2012 12:27 pm Post subject: |
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Hi all !
I realized today that i have a smd with an undumped/unknown bios 3.3C .
So i have dumped it with my double pro fighter .
the difference between 3.3 & 3.3c : in the menu "load file , save file " is back again like in 3.1g version !
https://rapidshare.com/files/458231229/bios3.3c.rar |
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KanedaFr
Administrateur
Joined: 29 Aug 2006
Posts: 635
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| Posted: Sat Feb 04, 2012 2:03 am Post subject: |
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| disassembly as soon as possible |
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KanedaFr
Administrateur
Joined: 29 Aug 2006
Posts: 635
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| Posted: Fri May 25, 2012 11:26 pm Post subject: |
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I'm back to the office so I was able to take some times for this 
http://gendev.spritesmind.net/files/bsys/smd/bios_33c_analysis.zip
Not a lot of new stuff :
- (re)add the way to load/dump in/from DRAM (like greatfunky already said)
- removed some unused code (some more still here)
It's cleary the best of the bios with 16k page
I also started to port the 3.3c bios to WLA DX so it will be a open source bios 'soon'  |
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greatfunky
Newbie
Joined: 31 Oct 2011
Posts: 4
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| Posted: Sat May 26, 2012 9:32 am Post subject: |
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i'm glad to see that 3.3c bios is the best  , i think that bios is the last of the 16k versions because i have also a 4.1-A smd and their serial numbers are close . |
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KanedaFr
Administrateur
Joined: 29 Aug 2006
Posts: 635
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| Posted: Tue May 29, 2012 12:30 pm Post subject: |
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There is something I don't understand....
On every bios, there is a vector table
| Code: | .org $0000
jp RESET
jp print_hexascii_byte
jp print_msg_at_HL
jp VDP_cls
jp init_VDP_and_character_set
jp loadCartInDRAM
jp handle_pc_command |
How these interrup handler are called ?
RESET is called at startup, ok...but what about the others ?
I didn't find any rst XX on disassemby so I assume it's an hw interrupt call (strage for a "print_msg_at_HL"!)
from Charles's SMS tech doc,
| Quote: | The interrupting device can place a single or multi-byte opcode on the
data bus for the Z80 to fetch and execute when an interrupt occurs. |
but, unless I missed something, the INT isn't connected on Genny so this can't happen...
Note all but RESET are in fact called from anywhere on the code and use a basic "ret" not "retn" so I suspect the vector table is invalid.
What do you think ? |
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