Forums

Sega Master System / Mark III / Game Gear
SG-1000 / SC-3000 / SF-7000 / OMV
Home - Forums - Games - Scans - Maps - Cheats - Credits
Music - Videos - Development - Hacks - Translations - Homebrew

View topic - Question about SMS 1

Reply to topic
Author Message
  • Joined: 12 Jul 1999
  • Posts: 882
Reply with quote
Question about SMS 1
Post Posted: Wed Jul 28, 1999 10:05 am
OK. On the original SMS, there is a port underneath it and at the back, kinda like the one on the side of the Mega Drive.
There are also little slots underneath the unit where something can slide into.
What was this for?
  View user's profile Send private message
depet
  • Guest
Reply with quote
Post Posted: Wed Jul 28, 1999 10:45 am
Quote
> OK. On the original SMS, there is a port underneath it and at the back, kinda like the one on the side of the Mega Drive.
> There are also little slots underneath the unit where something can slide into.
> What was this for?

this is only a cleaning slot for the interface according to my manual...
(I think you mean the snes-like slot)
 
Nyef
  • Guest
Reply with quote
Post Posted: Wed Jul 28, 1999 1:11 pm
Quote
> OK. On the original SMS, there is a port underneath it and at the back, kinda like the one on the side of the Mega Drive.
> There are also little slots underneath the unit where something can slide into.
> What was this for?

The only "slots" that I recall seeing on the bottom of my SMS were for ventilation.

The expansion interface is another matter. It's probably connected to most if not all of the system
bus, possibly the sound and video outputs as well. It would be a great place to hook up an FM
system or something. :-)

--Nyef
 
Eric
  • Guest
Reply with quote
Post Posted: Wed Jul 28, 1999 5:12 pm
Quote
> OK. On the original SMS, there is a port underneath it and at the back, kinda like the one on the side of the Mega Drive.
> There are also little slots underneath the unit where something can slide into.
> What was this for?

I'm with Nyef on this one.

All indications point to that port being a connection to the system bus. I believe the cartridge port is logically the same connection even though the physical connector is different. I'm betting with the appropriate physical connector, you could run a game cartridge off of that port.

There's a lot of possiblity here. With a bus connection, a variety of different hardware devices could be connected. The difficulty is the limited number of interrupt pins. Of course, before we can do any of that, we need to be able to execute our home-made software on the real hardware...

Eric
 
Nyef
  • Guest
Reply with quote
Post Posted: Wed Jul 28, 1999 6:36 pm
Quote
> I'm with Nyef on this one.

Oh, goody. :-)

Quote
> All indications point to that port being a connection to the system bus. I believe the cartridge
> port is logically the same connection even though the physical connector is different. I'm
> betting with the appropriate physical connector, you could run a game cartridge off of that port.

Or a system BIOS.

Quote
> There's a lot of possiblity here. With a bus connection, a variety of different hardware devices
> could be connected. The difficulty is the limited number of interrupt pins. Of course, before
> we can do any of that, we need to be able to execute our home-made software on the real hardware...

Actually, I just had an idea on how to add vectored interrupts via this port. What you would do is
monitor the IRQ line for an interrupt from the VDP, and provide the interrupt vector during the
following M1 cycle as per normal. Adding other interrupts at that point would be trivial.

So, who wants to design and build a computer system based around the SMS? We can add an IDE
interface, keyboard, 10Base-T port, maybe a modem, etc. Download SMS roms directly to your SMS. :-)

Quote
> Eric

--Nyef
 
  • Joined: 12 Jul 1999
  • Posts: 882
Reply with quote
Post Posted: Thu Jul 29, 1999 4:36 am

Quote
> > I'm with Nyef on this one.

> Oh, goody. :-)

> > All indications point to that port being a connection to the system bus. I believe the cartridge
> > port is logically the same connection even though the physical connector is different. I'm
> > betting with the appropriate physical connector, you could run a game cartridge off of that port.

> Or a system BIOS.

I actually thought that this was evidence of the existance of a development kit.

Quote
> > There's a lot of possiblity here. With a bus connection, a variety of different hardware devices
> > could be connected. The difficulty is the limited number of interrupt pins. Of course, before
> > we can do any of that, we need to be able to execute our home-made software on the real hardware...

> Actually, I just had an idea on how to add vectored interrupts via this port. What you would do is
> monitor the IRQ line for an interrupt from the VDP, and provide the interrupt vector during the
> following M1 cycle as per normal. Adding other interrupts at that point would be trivial.

> So, who wants to design and build a computer system based around the SMS? We can add an IDE
> interface, keyboard, 10Base-T port, maybe a modem, etc. Download SMS roms directly to your SMS. :-)

Now there is a cool idea!!!!
Think about it, what better way to play your SMS ROMs?
You could even take used SMS systems and replace the CPU with one of those Z80 25MHz versions and sell them. Well, maybe not.
Surf the net on a SMS!!!
How cool!!!
(were you being sarcastic?)

Quote
> > Eric

> --Nyef

~unfnknblvbl
  View user's profile Send private message
depet
  • Guest
Reply with quote
Re: Question about SMS 1 - help
Post Posted: Thu Jul 29, 1999 7:47 am
I need some help on this topic.
after looking closer at my sms again (I had it opened once too...)
the only things I have are these:
-front/top
cart slot
card slot
2 multigame ports
on/off/reset/pause

-back
power
cinch for video/audio out
round 8-pole a/v out

-bottom
a gap that´s closed by a plastic-slider, leads direct to
the cart interface from the other side; can´t see more there´s
a piece of plastic (you mean that?)

anyway I´ve got the hangon/shunt version of the sms1 (smsplus)

so if it´s the bottom thingy you are talking about -
my sms-manual really says it´s for cleaning - or
have I to break the plastic to see more?
 
  • Joined: 12 Jul 1999
  • Posts: 882
Reply with quote
Re: Question about SMS 1 - help
Post Posted: Thu Jul 29, 1999 10:31 am

Quote
> -bottom
> a gap that´s closed by a plastic-slider, leads direct to
> the cart interface from the other side; can´t see more there´s
> a piece of plastic (you mean that?)

Yes! That's the thing I was after! I do not actually have a SMS1, I only have a SMS2, so when I came across this in a local 2nd hand store it intrigued me. I did not take the slider off for fear of breaking it and paying a whole $25AUD for it.
I'll take a photo of the slots I mean when I get my hands on one.
You know, like the slots that the metal thingie from the MegaCD slides into on the MegaDrive. I know what I mean...

Quote
> anyway I´ve got the hangon/shunt version of the sms1 (smsplus)

> so if it´s the bottom thingy you are talking about -
> my sms-manual really says it´s for cleaning - or
> have I to break the plastic to see more?
Cleaning?
Cleaning what?
~unfnknblvbl
  View user's profile Send private message
Nyef
  • Guest
Reply with quote
Post Posted: Thu Jul 29, 1999 2:08 pm
Quote
> I actually thought that this was evidence of the existance of a development kit.

Why? The fact that there were games for the system was ample evidence of that. :-)

I think it's evidence of someone being intelligent enough to add a means of future expansion.

Quote
> > So, who wants to design and build a computer system based around the SMS? We can add an IDE
> > interface, keyboard, 10Base-T port, maybe a modem, etc. Download SMS roms directly to your SMS. :-)

> Now there is a cool idea!!!!
> Think about it, what better way to play your SMS ROMs?

I know. That's why I thought of it. :-)

Quote
> You could even take used SMS systems and replace the CPU with one of those Z80 25MHz versions and sell them. Well, maybe not.

Not. You'd run into so many problems doing that it's not funny. Besides, you'd have to open the case to do it.

Quote
> Surf the net on a SMS!!!
> How cool!!!
> (were you being sarcastic?)

Not entirely. Designing and building the proposed system is beyond my current skill, but I could program it.

Quote
> > --Nyef

> ~unfnknblvbl

--Nyef
 
  • Joined: 12 Jul 1999
  • Posts: 882
Reply with quote
Post Posted: Thu Jul 29, 1999 2:41 pm
Quote
> > I actually thought that this was evidence of the existance of a development kit.

> Why? The fact that there were games for the system was ample evidence of that. :-)

I was led to believe that developers back in the "good old days" had to write/build their own stuff for developing games on the SMS

Quote
> I think it's evidence of someone being intelligent enough to add a means of future expansion.

Yeah, well, that too...

Quote
> > > So, who wants to design and build a computer system based around the SMS? We can add an IDE
> > > interface, keyboard, 10Base-T port, maybe a modem, etc. Download SMS roms directly to your SMS. :-)

> > Now there is a cool idea!!!!
> > Think about it, what better way to play your SMS ROMs?

> I know. That's why I thought of it. :-)

> > You could even take used SMS systems and replace the CPU with one of those Z80 25MHz versions and sell them. Well, maybe not.

> Not. You'd run into so many problems doing that it's not funny. Besides, you'd have to open the case to do it.

I was being slightly overexcited/facetious there

Quote
> > Surf the net on a SMS!!!
> > How cool!!!
> > (were you being sarcastic?)

> Not entirely. Designing and building the proposed system is beyond my current skill, but I could program it.

Hmm...
Maybe we should do this.
All that is really needed is to provide a connector from the expansion slot->LPT port and some software for either SMS or PC to allow reading of the HDD as a regular cartridge.
This would be especially cool for users of a TV tuner card. :>
Or maybe even just a device that plugs into the cartridge slot to allow reading of a standard 1.44MB floppy disk with some games on it.
Besides, doing all that would just turn it into a Mark III, wouldn't it?
Quote
> > > --Nyef

> > ~unfnknblvbl

> --Nyef

~unfnknblvbl
  View user's profile Send private message
depet
  • Guest
Reply with quote
Re: Question about SMS 1 - help
Post Posted: Fri Jul 30, 1999 8:47 am
Quote
>
> > -bottom
> > a gap that´s closed by a plastic-slider, leads direct to
> > the cart interface from the other side; can´t see more there´s
> > a piece of plastic (you mean that?)

> Yes! That's the thing I was after! I do not actually have a SMS1, I only have a SMS2, so when I came across this in a local 2nd hand store it intrigued me. I did not take the slider off for fear of breaking it and paying a whole $25AUD for it.
> I'll take a photo of the slots I mean when I get my hands on one.
> You know, like the slots that the metal thingie from the MegaCD slides into on the MegaDrive. I know what I mean...

> > anyway I´ve got the hangon/shunt version of the sms1 (smsplus)

> > so if it´s the bottom thingy you are talking about -
> > my sms-manual really says it´s for cleaning - or
> > have I to break the plastic to see more?
> Cleaning?
> Cleaning what?
> ~unfnknblvbl

the cart slot - from dust perhaps or corrosion - remember nes-shit?
 
depet
  • Guest
Reply with quote
Post Posted: Fri Jul 30, 1999 9:52 am
Quote
> > > I actually thought that this was evidence of the existance of a development kit.

> > Why? The fact that there were games for the system was ample evidence of that. :-)

> I was led to believe that developers back in the "good old days" had to write/build their own stuff for developing games on the SMS

> > I think it's evidence of someone being intelligent enough to add a means of future expansion.

> Yeah, well, that too...

> > > > So, who wants to design and build a computer system based around the SMS? We can add an IDE
> > > > interface, keyboard, 10Base-T port, maybe a modem, etc. Download SMS roms directly to your SMS. :-)

> > > Now there is a cool idea!!!!
> > > Think about it, what better way to play your SMS ROMs?

> > I know. That's why I thought of it. :-)

> > > You could even take used SMS systems and replace the CPU with one of those Z80 25MHz versions and sell them. Well, maybe not.

> > Not. You'd run into so many problems doing that it's not funny. Besides, you'd have to open the case to do it.

> I was being slightly overexcited/facetious there

> > > Surf the net on a SMS!!!
> > > How cool!!!
> > > (were you being sarcastic?)

> > Not entirely. Designing and building the proposed system is beyond my current skill, but I could program it.

> Hmm...
> Maybe we should do this.
> All that is really needed is to provide a connector from the expansion slot->LPT port and some software for either SMS or PC to allow reading of the HDD as a regular cartridge.
> This would be especially cool for users of a TV tuner card. :>
> Or maybe even just a device that plugs into the cartridge slot to allow reading of a standard 1.44MB floppy disk with some games on it.
> Besides, doing all that would just turn it into a Mark III, wouldn't it?
> > > > --Nyef

> > > ~unfnknblvbl

> > --Nyef

> ~unfnknblvbl

I had the same question some months back on the emucamp forum,
Eric said that the bus timing of the sms would be the problem.
So if you have a second sms left you can do some analizing
with the right tools and the right docs (no problems with
opening a sms, done that :)

The same rom/hd simulating thing was done with the c64 and
a simple cable, but keep in mind that althought the c64
is slower(1mhz) in most cases than the sms it had lotsa
more developers and docs from the official side...
 
Eric
  • Guest
Reply with quote
Post Posted: Fri Jul 30, 1999 3:48 pm
[Some talk about building a PC->SMS cartridge connector.]


Quote
> I had the same question some months back on the emucamp forum,
> Eric said that the bus timing of the sms would be the problem.
> So if you have a second sms left you can do some analizing
> with the right tools and the right docs (no problems with
> opening a sms, done that :)

I remember that, and I was about to say the same thing again.

There's a potential difficulty here: meeting the bus timing requirement for memory accesses.

Please understand, I do not know exactly how the Z80 bus works. It could be that the bus has some freedom as to how long memory accesses take. Though, I suspect, there is not a lot of freedom.

Certainly, it's a good idea, though. Any one want to seriously attempt this? I'd be happy to help.

Eric
 
depet
  • Guest
Reply with quote
Post Posted: Sat Jul 31, 1999 3:04 pm
Quote
> [Some talk about building a PC->SMS cartridge connector.]

>
> > I had the same question some months back on the emucamp forum,
> > Eric said that the bus timing of the sms would be the problem.
> > So if you have a second sms left you can do some analizing
> > with the right tools and the right docs (no problems with
> > opening a sms, done that :)

> I remember that, and I was about to say the same thing again.

> There's a potential difficulty here: meeting the bus timing requirement for memory accesses.

> Please understand, I do not know exactly how the Z80 bus works. It could be that the bus has some freedom as to how long memory accesses take. Though, I suspect, there is not a lot of freedom.

> Certainly, it's a good idea, though. Any one want to seriously attempt this? I'd be happy to help.

> Eric

all I have is a (sort of) high tech voltage/ampere/resisting(sp?)
metre, but I think you would need an oscilloscope(sp?)
anyway I'm no geek of technics, what would you need for
a serious analysation?
 
Reply to topic



Back to the top of this page

Back to SMS Power!