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 [email protected] (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