Stupid question about the SMS

[joeybastard]

I've been using the excellent Sega Master System/Colecovision emulator called Meka a lot lately. Since this EMU can do both systems, I have to assume a similarity in some of the original hardware. So here's my stupid question: Could an adapter be made for CV carts to make them playable on a real SMS?

 

I'm guessing the answer is no but it got me thinking so I wanted to ask.

[+FujiSkunk]

It might be possible. Several hardware bits, including the CPU and the sound chip, are the same in both systems, and the CPU even runs at the same speed. However, I imagine there are just enough differences in the graphics hardware that such an adapter would be tough to pull off. For example, the stats say the SMS has 16 sprites while the ColecoVision has 32.

Edited December 11, 2007 by skunkworx

[joeybastard]

Yeah, I kind of figured it would be too good to be true if it could be done somewhat easily.

 

Thanks

[shadow460]

*gears turning*

 

Colecovision on a Game Gear, perhaps? Or is the hardware not far enough advanced over the SMS to make much difference?

[A Sprite]

*gears turning*

 

Colecovision on a Game Gear, perhaps? Or is the hardware not far enough advanced over the SMS to make much difference?

 

The Game Gear can handle 64 sprites.

[+FujiSkunk]

*gears turning*

 

Colecovision on a Game Gear, perhaps? Or is the hardware not far enough advanced over the SMS to make much difference?

 

The Game Gear can handle 64 sprites.

 

Unfortunately the Game Gear's screen resolution is too low for the ColecoVision. The Game Gear can switch to SMS mode for a higher resolution, of course, but depending on how restricted that mode is, you still run into sprite and memory limitations (8KB for the SMS vs. 24KB [combined system and video] for the ColecoVision).

[+Psionic]

I've been using the excellent Sega Master System/Colecovision emulator called Meka a lot lately. Since this EMU can do both systems, I have to assume a similarity in some of the original hardware. So here's my stupid question: Could an adapter be made for CV carts to make them playable on a real SMS?

 

I'm guessing the answer is no but it got me thinking so I wanted to ask.

The DINA/Telegames Personal Arcade will play both Sega SG-1000 and ColecoVision games, so there is some degree of compatibility between the two. It may be possible to build an adapter, I suppose...but why bother?

[A Sprite]

Weren't the Sega Master system cards SG-1000 holdovers? The SG-1000 could display 32 sprites, same as the Colecovision.

 

Also, how many Colecovision games display all 32 sprites?

[joeybastard]

I've been using the excellent Sega Master System/Colecovision emulator called Meka a lot lately. Since this EMU can do both systems, I have to assume a similarity in some of the original hardware. So here's my stupid question: Could an adapter be made for CV carts to make them playable on a real SMS?

 

I'm guessing the answer is no but it got me thinking so I wanted to ask.

The DINA/Telegames Personal Arcade will play both Sega SG-1000 and ColecoVision games, so there is some degree of compatibility between the two. It may be possible to build an adapter, I suppose...but why bother?

 

 

I was just curious really. I don't have the technical skills to do it anyway. It had just occurred to me that it might be nice to able to just pop in a CV game into my SMS, which would yield me a better picture(composite from my SMS), and no power switch hassles. I know these things are available on a CV if I want to pay for them but if it could be done with a cheap adapter, so much the better.

[Bruce Tomlin]

The answer is NO, and for multiple reasons. The main reason is the Colecovision's BIOS ROM, as crappy as it may be (I've personally been able to optimize over 12% out of it) most games depend on it being there. The other reason is that the I/O ports (particularly the controllers) are laid out differently.

 

The DINA started out as Colecovision clone, but was able to change itself around enough internally to emulate an SG-1000, the predecessor to the SMS/Mark III. The SG-1000 has the same parts as the Coleco, but no ROM, and a different I/O port layout that was kept in the SMS.

[StarBlazer692003]

I *REALLY* hope this thread isn't dead...maybe this will "reviatlize it"....

Okay.....the SMS hardware is an "upgraded" version of the Colecovision hardware.

i.e. The video chip is upgraded (new modes/capabilities), the CPU is the same (Z80A @ ~3.58mhz?), running at the same speed, and has the same amount of video memory.

The SMS has 8K RAM

The CV has 1K?

 

Side note: The same Audio & Video chips were ALSO the ones used in the TI-994/a! (TMS 9918A-Video) (SN76489-SOUND)

(The video chip (VDC) was also used in early MSX models)

(The PSG/sound chip was also used in a large handfull of arcade games (Mostly Sega ones!)

(I can't find the part # of the SMS video chip...but it's a bit customized)

 

Differences:

probably the Memory map (possibly some I/O stuff too, and the BIOS/Kernel):

 

(I'm not really sure how "necessary" the CV kernel is to running games, besides the title screen, menu screen, and the (in)famous delay!)

 

Master System/Mark III (assuming Sega mapper)
Region Maps to
$0000-$03ff ROM (unpaged)
$0400-$3fff ROM mapper slot 0
$4000-$7fff ROM mapper slot 1
$8000-$bfff ROM/RAM mapper slot 2
$c000-$dfff System RAM
$e000-$ffff System RAM (mirror)
$fff8 3D glasses control
$fff9-$fffb 3D glasses control (mirrors)
$fffc Cartridge RAM mapper control
$fffd Mapper slot 0 control
$fffe Mapper slot 1 control
$ffff Mapper slot 2 control

Where control registers overlap with mirrored RAM, values written will affect the device and also be written to RAM. Reads simply return the value stored in RAM.
SG-1000/SC-3000
Region Maps to
$0000-$bfff Cartridge (ROM/RAM/etc)
$c000-$c7ff System RAM
$c800-$ffff System RAM (mirrored every 2KB)

-------------------------------------------------------------------

 

COLECOVISION memory map:

0000H - BIOS ROM
.
1FFFH
2000H - Expansion port
.
3FFFH
4000H - Expansion port
.
5FFFH
6000H - Start of RAM (1K mapped into an 8K spot)
.
7FFFH
8000H - Cart ROM (broken into 4 sections, each enabled seperately)
.
FFFFH

 

The ColecoVision contains a ROM which essentially acts as a BIOS for the system. Upon startup, it begins to execute code at 0000H. The first step executed is a check to see if a cart is plugged in. This is performed by checking two locations in the cart's memory - if the two bytes read are 55H and AAH then the ColecoVision knows a cart is in the system. Otherwise, it displays the standard "Turn Power Off Before..." screen.

If a cart is in the system, the BIOS passes controlto the cart. The cart can then use some, all, or none the functions found in the BIOS. Some of the functions provided in the BIOS include the title screen and game select screen.

The famous twelve second delay is part of the titlescreen routine. - 8

The address range for cartridges is 8000H to FFFFH,a total of 32K. - 29, 31

 

I/O Map:

00-1F - No Connection
20-3F - No Connection
40-5F - Video
60-7F - Video
80-9F - No Connection
A0-BF - No Connection
C0-DF - Sound
E0-FF - Controllers; E2 is special, as wellas E0 - E0 appears to be the readback, and E2 appears to be the scan - 39

 

(I ripped these off from a couple webpages that I can't remember right now....)

 

---

okay

---

 

The upgraded SMS video chip has all the "old" modes in it (The Gamegear may not, and the Genesis has SOME of the modes, but not most of the "old" modes)

Old modes are also called VDP modes!

I hope this gives someone out there enough information to do something with this.

Since most CV games are <32K.....it should only take "a little while" to remap the game to a new memory location (in SMS memory), and change all the VDP and PSG addresses to where they are in the SMS (all the "old" registers are in the same places...just some new ones!)

(If someone has enough coffee/beer/patience/insanity....it doesn't take THAT LONG to go through 32k of assembly!)

 

I don't know what the I/O differences are, or whether an SMS is capable of reading a full CV controller (all buttons, trackball, super-action controller, etc...)

(or what the I/O chips are, or even if they are the same or different! ?)

 

Theoretically.....this CAN be done (the SMS being a superset of the CV hardware)

 

If we want to mess with running ADAM software on the SMS....it'll be like the CV, but a superset of it (with more features--though......not a whole hell of a lot of them)

 

Thank you

-Jess Sosnoski

starblazer692003@gmail.com

(and on FaceBook too!)

 

If anyone finds this useful, email me back, friend me on facebook, or something (both?)

I read my Email once every 2 centuries, so it may take me about a week until I noticed any replies

 

[Uzumaki]

So it's very likely CV games can run on SMS with minor adjustment to account for all the changes in memory mapping. What about running small SMS games on a CV? Some of the early small SMS games with small memory requirement might work on CV?

 

Wonder if it's practical to build an adapter that traps memory call and redirects them to different location and allows CV cart to work on SMS console?