Author Topic: New DIY Project released: The MegaROM  (Read 23649 times)

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Offline Bryce

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New DIY Project released: The MegaROM
« on: 17:58, 17 October 10 »
Geetings All,
         for most of us, winter is just around the corner (or never actually went away if you live in England) and what better way to keep warm, than to fire up your soldering iron and get busy with my latest DIY project.

The MegaROM is a very small low-cost ROMBoard, which if you don't yet own a ROMBoard you should and if you do have one, it probably takes up way too much space. The MegaROM packs 8 or 16 ROMs into a single 1Mbit or 2Mbit EPROM and servers them up to the CPC as if they were separate 16k EPROMs, just the way the CPC likes.

The project was born out of conversations I had with TFM/FS a few weeks back and this Wiki page ( http://www.cpcwiki.eu/index.php/MegaROM )  is the result.

Oh and by the way, No. I won't be building a batch of them, but if you talk nicely to TFM/FS, he may be able to help you there... ;)

Hope you like it,
Bryce.
« Last Edit: 23:07, 17 October 10 by Bryce »

Offline robcfg

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Re: New DIY Project released: The MegaROM
« Reply #1 on: 21:22, 17 October 10 »
You know, it looks very simple so that I could make one, but it's never going to look so professionally done as yours, hehehe  :P


Nice piece of hardware!

Offline redbox

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Re: New DIY Project released: The MegaROM
« Reply #2 on: 23:04, 17 October 10 »
This is fantastic as I've been contemplating making a ROMbox for ages.  :)

Offline steve

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Re: New DIY Project released: The MegaROM
« Reply #3 on: 05:09, 18 October 10 »
Does this use an EPROM, and if so is there programming circuitry on-board.

Is there a flash rom that could be used (and written to) instead of the EPROM?

Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #4 on: 10:11, 18 October 10 »
Hi Steve,
         the board can accept standard UV or Flash EPROMs, but it can't write to either of them, you'll need an EPROM burner to do that. The goal was to make a very low-cost ROMBoard and features like that would have greatly increased the price. If it's a writeable ROMBoard you're looking for, then you should take a look at the Inicron interfaces, but they'll cost you a lot more to build.

Bryce.

Offline Gryzor

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Re: New DIY Project released: The MegaROM
« Reply #5 on: 10:35, 18 October 10 »
Does this use an EPROM, and if so is there programming circuitry on-board.

Is there a flash rom that could be used (and written to) instead of the EPROM?

Even thought I've discussed this with Bryce and he's told me why not (cost is, I think, the main reason - MegaROM is supposed to be a low-cost solution), I have to say - this would be the ultimate...

Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #6 on: 12:09, 18 October 10 »
I know, it would be nice, but...

1. That already exists, it's called the Inicron RamRom Box.

2. The MegaROM cost around 10€ as is, with flash or UV EPROM write functionality it would be around 50-60€, twice the size, a double sided PCB and difficult to build.

3. The MegaROM holds up to 256k of code, writing this with an EPROM burner takes about 4 seconds and the images are usually on your PC anyway. On the CPC, you'd need to get the images one by one and write them individually. A task that would take ages.

4. The MegaROM was designed as a pure ROMBoard, cheap enough to distribute with pre-loaded software.

5. In case I haven't mentioned it.... That already exists, it's called the Inicron RamRom Box :)

Here's a suggestion, how about a 256k game for all CPCs that runs from ROM and can be sold / distributed on this board. The equivalent of a cartridge for standard CPCs.

The technical why not:

A quick explaination about writing to Flash and UV EPROMs.

UV EPROMs are electronically addressable (like RAM) when writing to them, this makes them quite simple to program (set WE pin low, set address, send data), but, they need high program voltages, depending on the type used, this can be as high as 12.5v which the CPC can't supply, so an additional PSU would be required.

Flash EPROMs aren't as easy to write to. It's not as simple as "set WE pin low and send the data", they have a command registry which needs instructions sent to it, although there are versions which can be programmed with 5V (standard flash also needs 12V to be written), it would need a lot of hardware to switch between normal and write modes and even more to store and send the required commands (ie: µP on the interface which could take control of both the data and address bus). This would just be a big, clumsy expensive device, that no-one would build or want.

If that really IS what some people want, then let me know, I can put together a plan, but it won't be the simple PCB you're expecting and I'm certainly not going to build one.

Battery-backed RAM is the easiest and most sensible solution, but just to mention it one last time..... That already exists, it's called the Inicron RamRom Box :D

Bryce.
« Last Edit: 12:11, 18 October 10 by Bryce »

Offline redbox

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Re: New DIY Project released: The MegaROM
« Reply #7 on: 13:46, 18 October 10 »
Do you know where I can get the PCB printed?

Or do I have to do something like this...?

And "It may also be compatible with the CPC plus, but this has not yet been tested."  Please someone tell me it will work  :(
« Last Edit: 13:52, 18 October 10 by redbox »

Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #8 on: 14:16, 18 October 10 »
Hi Redbox,
        as far as I know, TFM/FS intends having a batch built (I may be wrong here, TFM/FS should confirm this). So maybe that would be the easiest/cheapest way of getting one.

On the other hand, "Doing something like this" is more or less what I do (except I use UV photo-sensitive transfer instead of an Iron). The initial cost of the equipment is quite high, but well worth the bother, and you can make any PCB you want after that. It does take some practice though, before you get really good PCBs every time (the first few attempts will most likely be unusable).

I'm 99.99% sure that the MegaROM works on a CPC+ too, but I haven't tested it, cos' I don't own a plus. So I'll leave that comment there until someone has tested it.

Bryce.
« Last Edit: 20:29, 18 October 10 by Bryce »

Offline redbox

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Re: New DIY Project released: The MegaROM
« Reply #9 on: 14:48, 18 October 10 »
as far as I know, TFM/FS intends having a batch built (I may be wrong here, TFM/FS should confirm or deny this). So maybe that would be the easiest/cheapest way of getting one.

Thanks for explaining the process and hopefully TFM/FS is making some...  :)

I would love to start making my own stuff but think I need to be more competent as I have only soldered a parallel cable so far!

Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #10 on: 15:20, 18 October 10 »
Every electronics person started with a simple cable or something similar. You'll only gain the competence and skills with practice, lots of it. The MegaROM may be a little bit complicated as a first project though, so try some other simpler PCBs first to perfect the process, before you take on more complicated layouts.

I just started my very first real z80 assembly program (did some basic stuff waaay back in college which I've completely forgotten), so I know how it feels to be at point zero :D I'm sure my "challenges" with the language would make most of the programmers here laugh for a week.

Bryce.

Offline ukmarkh

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Re: New DIY Project released: The MegaROM
« Reply #11 on: 18:44, 18 October 10 »
TFM/FS... can we have a MEGAROM for Xmas please???

Offline TFM

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Re: New DIY Project released: The MegaROM
« Reply #12 on: 04:21, 19 October 10 »
Hi all!
 
First I want to tell Bryce my very best congratulations! You really did it great, especially when looking at the short time, you only had few weeks. And the ROM banking of 0 and 7 seems to be tricky. However the MegaROM is exactly what I had in mind at first. And it provides what we need for the CPC.
 
Indeed I'm going to produce 50-100 units of the MegaROM, but it's questionable if I can do that in this year. The best PCB producer must be found... drilling holes?... ICs.... soldering... ??? It will take time, but it will be done  :)
 
The original sence for me to ask Bryce if he can create a low-cost, high-power ROM expansion was to provide a means for anybody to run FutureOS (now please don't throw sharp things at me ...  ;) ). FutureSoft (Bryce, Tolkin and me) is going to releases a couple of games (also not in this year, we got enough from Spain  :P ) and you will need FutureOS to run them. Tolkin always pledged for an Amsdos version, but this is just not possible with only 128 KB. So there is a need for a common solution. First I asked for 128 KB, but 256 KB are just one Euro more expensive, so there we go  ;D
 
This means 50-100 MegaROMs will be produced, equipped with FutureOS and shipped in bundle with one of our games on disc (3" or 3.5").
 
Since the MegaROM provides a lot of ROM I also thought of burning some other usually needed software into the EPROM / FlashROM. This is what I have in mind:
 
 ROM 01: Dobbertin R-DOS (expanded 16 KB verison), provides a RAM-disc C:
 
 ROM 04: MAXAM assembler
 ROM 05: PROTEXT wordprocessor
 ROM 06: Dobbertin XD-DOS, expanded DOS supporting V-DOS format
 
(ROM 07: ParaDOS as AmsDOS replacement, but soft-off by XD-DOS?)

 ROM 10: FutureOS ROM A
 ROM 11: FutureOS ROM B
 ROM 12: FutureOS ROM C
 ROM 13: FutureOS ROM D
 
(ROM 14: FutureOS IDE expansion ROM?)
 
 
Now:
- Instead of XD-DOS you can also use other DOS like ParaDOS or V-DOS
- ROM 0 can contain a patched BASIC that ignores ,p for example
- The above written list of ROMs is just a first idea and I'm curious which ROMs do the most of you like to see in this wonderful ROM expansion.
 
« Last Edit: 04:28, 19 October 10 by TFM/FS »
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Offline Gryzor

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Re: New DIY Project released: The MegaROM
« Reply #13 on: 09:40, 19 October 10 »

@Bryce:

All valid points. Still, it'd be sooo nice :D

I just hope that people with EPROM programmers can offer a service (at a price, even) to burn ROMs for the rest of us poor have-nots...


Oh - wait: is the chip soldered or socketed? I bet socketed??

Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #14 on: 10:36, 19 October 10 »
It's socketed of course, but just a standard Socket, it's not worth the expense to put a ZIF Socket (those sockets with the little lever) because it won't be removed that often.

And Gryzor, just for you (and anyone else who's interested), I've decided to take a serious look at a write-able Flash design, to see how cheaply it could be made, but it will be a "dumb" circuit, which means it will need a fancy program in the CPC to write something to it, it won't be a simple "copy it across"  solution and I'll need some support from somebody who actually knows how to program z80 (which I don't).

I'll let you know how it goes....

Bryce.

Offline arnoldemu

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Re: New DIY Project released: The MegaROM
« Reply #15 on: 11:31, 19 October 10 »
It's socketed of course, but just a standard Socket, it's not worth the expense to put a ZIF Socket (those sockets with the little lever) because it won't be removed that often.

And Gryzor, just for you (and anyone else who's interested), I've decided to take a serious look at a write-able Flash design, to see how cheaply it could be made, but it will be a "dumb" circuit, which means it will need a fancy program in the CPC to write something to it, it won't be a simple "copy it across"  solution and I'll need some support from somebody who actually knows how to program z80 (which I don't).

I'll let you know how it goes....

Bryce.
I know z80 well. And I would be happy to write code to program it.
I would also love one of these.
My games. My Games
My website with coding examples: Unofficial Amstrad WWW Resource

Offline robcfg

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Re: New DIY Project released: The MegaROM
« Reply #16 on: 12:48, 19 October 10 »
I'm interested in one MegaROM.


Meanwhile, is it possible to have SymbOS and FutureOS roms in the Symbiface II?


I haven't played with the rom management utilities but it seems that in my card, the SymbOS rom is in a slot that FutureOS would use. Can I move the SymbOS rom to another slot or does it contain some hardcoded values as FutureOS roms?

Offline CPCIak

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Re: New DIY Project released: The MegaROM
« Reply #17 on: 13:19, 19 October 10 »
I'm interested in one MegaROM.

Me too, please!

Offline redbox

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Re: New DIY Project released: The MegaROM
« Reply #18 on: 13:44, 19 October 10 »
Me too, please!

Me three please  :)

Offline trocoloco

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Re: New DIY Project released: The MegaROM
« Reply #19 on: 13:47, 19 October 10 »
Me three please  :)

this MegaROM sounds interesting, so me too please

Offline eliot

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Re: New DIY Project released: The MegaROM
« Reply #20 on: 16:50, 19 October 10 »
And Gryzor, just for you (and anyone else who's interested), I've decided to take a serious look at a write-able Flash design, to see how cheaply it could be made, but it will be a "dumb" circuit, which means it will need a fancy program in the CPC to write something to it, it won't be a simple "copy it across"  solution and I'll need some support from somebody who actually knows how to program z80 (which I don't).
I think the target is less than 35€ like the Ramcard http://www.cpcwiki.eu/index.php/Ramcard_128
Pulkomandy proposes a batch for Ramcard here : http://pushnpop.net/index.php?action=posts&category=4&id=56&page=2#lastpost
Is your project is to have 256 Kb like in the MegaRom? Or more? 



Offline Bryce

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Re: New DIY Project released: The MegaROM
« Reply #21 on: 17:07, 19 October 10 »
Hi Eliot,
       When you talk about "Target price" I assume you mean the sale price? As it's a DIY project, I just speak about construction prices, which I plan to keep below 15€. I also plan it to be a 256k card with no 128k option. It would be very similar to a RAMCard, but it wouldn't require a battery.

I don't intend producing batches of them, but all the plans will be released in the wiki, so if anyone else wants to produce them, they are more than welcome to. Then they can decide how much the sales price should be.

Bryce.

Offline eliot

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Re: New DIY Project released: The MegaROM
« Reply #22 on: 18:17, 19 October 10 »
Target price was for me a way to say that a project with the same features than the Ramcard is interesting if it's cheaper and parts easy to find for noobs...  :D
Eliot


Offline TFM

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Re: New DIY Project released: The MegaROM
« Reply #23 on: 18:31, 19 October 10 »
And Gryzor, just for you (and anyone else who's interested), I've decided to take a serious look at a write-able Flash design, to see how cheaply it could be made, but it will be a "dumb" circuit, which means it will need a fancy program in the CPC to write something to it, it won't be a simple "copy it across"  solution and I'll need some support from somebody who actually knows how to program z80 (which I don't).

No problem, therefore we have a hardware, a graphic and a software person in FutureSoft. And since software is my part, I will do that. The most important thing is to select the right I/O ports (let me care about this). Let's talk about the details via email. And if we have a working solution, we'll release it.
BTW: For the MegaFlash I can use my ROManager software, which provides additional functionallity. It wouldn't be much work to adapt it.
 
Meanwhile, is it possible to have SymbOS and FutureOS roms in the Symbiface II?
I haven't played with the rom management utilities but it seems that in my card, the SymbOS rom is in a slot that FutureOS would use. Can I move the SymbOS rom to another slot or does it contain some hardcoded values as FutureOS roms?

You can load SOS in all "slots" / ROM-selects between 1-6 and 7-15. It is not executed in ROM, it just gets copied from ROM to RAM, so it needs no fixed addresses.
 
On the other hand FutureOS is less flexible, it needs fixed ROM selects, because it runs in ROM. But if you write me a PM and tell me which slots / ROM-selects you would like, then I will adapt that for you. There's also a tool out in the net, that can do that. But I'm glad to help where ever I can.
 
« Last Edit: 18:47, 19 October 10 by TFM/FS »
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

Offline Gryzor

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Re: New DIY Project released: The MegaROM
« Reply #24 on: 09:35, 20 October 10 »
Code: [Select]
[quote author=Bryce link=topic=1464.msg14713#msg14713 date=1287473815]
It's socketed of course, but just a standard Socket, it's not worth the expense to put a ZIF Socket (those sockets with the little lever) because it won't be removed that often.
Yes, that's what I meant too - a ZIF one would just be flashy (still, nice :D ).

And Gryzor, just for you (and anyone else who's interested), I've decided to take a serious look at a write-able Flash design, to see how cheaply it could be made, but it will be a "dumb" circuit, which means it will need a fancy program in the CPC to write something to it, it won't be a simple "copy it across"  solution and I'll need some support from somebody who actually knows how to program z80 (which I don't).

Awwww what? No USB connection to flash it from the PC? :(

Just kidding, I know that ideas are easy, implementation and low costs are hard.

Still, really, and I propose this for the community, if someone with a burner could provide a burning service, like the magazine DVDs I've been sending out, this would be sweet...