An idea for a development pcb

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devzone
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An idea for a development pcb

Post by devzone » Thu Jun 12, 2008 10:48 am

Ive been doing a little research on "Play Tv" which is basically a genesis console on a chip containing a rom programmed with 6 games, this games can be picked up extremely cheaply

What I plan to do make a small easy to construct pcb using the minimum of cheap simple logic (no fpga's or other complex stuff) to attach to the play tv pcb containing the following

* Secure Digital card socket (SD Card) for games / applications
* pc link port
* Bios flash rom containing Initializer, full fat filing system, command shell to access filing system including commands for load/save/dir etc
* 128MByte sdram (data loaded on demand from the sd card)
* If I can find an RGB output on the Play TV then i'll also throw in a Jamma connector and Audio amplifier making this probably the tinyest jamma multigame system around ?

I planned this platform as a development system for new programs and not just to run copied games so I have not put much thought into the various backup ram schemes used by comercial games but I will look into this

A cartridge version would allow the same system for the genesis console

At the moment its just a few scribbles on paper and I would appreciate any feedback you have and suggested changes, I hope there will be some developers here interested in this gizmo

I hope to have some spare time within the next few months to make a start on this

TmEE co.(TM)
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Post by TmEE co.(TM) » Thu Jun 12, 2008 11:10 am

it will all be a major pain in the ass, and some similiar discussion (well, about a flashcart) has already happened here. Look for Open source flashcart thing or something...
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Shiru
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Post by Shiru » Thu Jun 12, 2008 11:18 am

How easy to buy that Play TV and how much it will cost? I think it's much harder than buy usual SMD or clone.

About conception. It's common idea overall. I had same idea some time ago (but with SRAM instead of SDRAM, and SD was only option), and HardWareMan plans to make something similar.

Btw, can you remove banner from your signature? You have link to your site in profile anyway, no need to have such big picture in each post.

8bitwizard
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Post by 8bitwizard » Thu Jun 12, 2008 12:54 pm

I would rather do a sidecar board on the expansion connector. Genuine Sega units are easier to find and should be easier to work with than a geniclone. And for a dev board, I think I'd rather have an ethernet port, though SD or MMC would probably be a bit easier to program than ethernet. It's just that it's a major pain to have to physically move something every time you want to try a new code load, and you'll go nuts before you can finish anything. If it weren't for emulators, I couldn't have gotten as far as I have programming the Genesis.

Oh, and you do know that the 68000 only has a 16MByte total address space, right? And half of that really can't be used for external RAM, so the extra 120MBytes of RAM isn't going to do you much good. Also, there's no point in using SDRAM other than it's easier to find those chips new. The 68000 is way too slow to need the extra speed. A pair of 30-pin 4 megabyte SIMMs is probably a better choice if you're going to the trouble of implementing a DRAM controller.

devzone
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Post by devzone » Thu Jun 12, 2008 1:34 pm

TmEE co.(TM) wrote:it will all be a major pain in the ass, and some similiar discussion (well, about a flashcart) has already happened here. Look for Open source flashcart thing or something...
Thanks ive just read through all seven pages, its a shame that it didnt go very far (unless I missed something ?)
My project will take a little effort but not really a "pain in the ass" as such
Shiru wrote:How easy to buy that Play TV and how much it will cost? I think it's much harder than buy usual SMD or clone.
Very easy to find http://www.radicagames.com/where-to-buy.php , I see them for sale in the UK everywhere for as low as £6.99
Shiru wrote:About conception. It's common idea overall. I had same idea some time ago (but with SRAM instead of SDRAM, and SD was only option), and HardWareMan plans to make something similar.

Btw, can you remove banner from your signature? You have link to your site in profile anyway, no need to have such big picture in each post.
Seems like a popular topic here, I hope these guys get their designs up and running, I hope to get mine working too
I have reduced my signature image as requested
8bitwizard wrote:I would rather do a sidecar board on the expansion connector. Genuine Sega units are easier to find and should be easier to work with than a geniclone. And for a dev board, I think I'd rather have an ethernet port, though SD or MMC would probably be a bit easier to program than ethernet. It's just that it's a major pain to have to physically move something every time you want to try a new code load, and you'll go nuts before you can finish anything. If it weren't for emulators, I couldn't have gotten as far as I have programming the Genesis.
I will be including a pc link port (see my original post) and link routines in the bios to allow transfer from the pc to sdram for quick testing and the sdcard for more permanent storage
I did say that a cartridge version would allow it to be used on the genesis and will look into this
8bitwizard wrote:Oh, and you do know that the 68000 only has a 16MByte total address space, right? And half of that really can't be used for external RAM, so the extra 120MBytes of RAM isn't going to do you much good. Also, there's no point in using SDRAM other than it's easier to find those chips new. The 68000 is way too slow to need the extra speed. A pair of 30-pin 4 megabyte SIMMs is probably a better choice if you're going to the trouble of implementing a DRAM controller.
I was going to implement banked memory as either a single 8MByte * 16 banks or split as two 4MByte * 32 banks (undecided as yet)
The 68000 will access the ram at its usual slow pace so access times are not a problem and any speed sdram should work fine
Yes it doesnt have to be sram, I could use simms or other types of dram


Thank you all for your comments, much appreciated
Last edited by devzone on Thu Jun 12, 2008 2:17 pm, edited 1 time in total.

tails92
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Post by tails92 » Thu Jun 12, 2008 2:13 pm

But does Radica ship to EU contries? All I see is big american stores and some british ones.

Chilly Willy
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Post by Chilly Willy » Thu Jun 12, 2008 3:39 pm

DevSter has a nice page on the Radica, including a ROM pinout so you can add a cart connector.

http://devster.monkeeh.com/sega/radica/

TmEE co.(TM)
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Post by TmEE co.(TM) » Fri Jun 13, 2008 3:16 pm

I don't really think there's need for HW in MD dev anymore. You can do most debugging in Kmod, close to real HW testing in Fusion and that's really all you need. I use my MD2 usually to know that my code still runs on real HW and to listen music and play games as emu is still an emu.
Mida sa loed ? Nagunii aru ei saa ;)
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devzone
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Post by devzone » Mon Aug 11, 2008 3:22 pm

TmEE co.(TM) wrote:I don't really think there's need for HW in MD dev anymore. You can do most debugging in Kmod, close to real HW testing in Fusion and that's really all you need. I use my MD2 usually to know that my code still runs on real HW and to listen music and play games as emu is still an emu.
I had not updated my emulators in a while but now have and agree with you that hardware development boards are no longer required

I may still build a modded radica containing rom/ram/sdcard just for a portable fun system

furrykef
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Post by furrykef » Mon Aug 11, 2008 9:58 pm

TmEE co.(TM) wrote:I don't really think there's need for HW in MD dev anymore. You can do most debugging in Kmod, close to real HW testing in Fusion and that's really all you need. I use my MD2 usually to know that my code still runs on real HW and to listen music and play games as emu is still an emu.
There's also the point that a lot of people find the original machine to be a lot more fun than emulators. :)

- Kef

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