Mega Games Cartridge for the Electron MGC

[daveejhitchins]

The other day I was musing over something Jason mentioned at the 2014 Wakefield Show and decided it would, probably, make a good project.

Dave H
******************************************************************************************************************
I'll be keeping up-to-date the attached Excel file which will show which games are available and working. Note: I've decided to release the MGC built and in a cartridge case only (with exceptions for Forum members)! First orders will have an Acorn cartridge case. Once these run-out It'll be 3D printed cases. If you have your own case, let me know and I'll supply a built board only - I prefer them in-a-case because there's a large Surface Mount memory device and other SM devices used - also it's a small board and could easily be fitted the wrong way round!

What is the Mega Games Cartridge?
In a nutshell - - 4MB x 8 bits of programmable memory! In the MGC, this is organised as 256 x 16K blocks. Either 1 or 2 16K blocks can be 'visible' at any one time. It is designed to be plugged into an Electron Cartridge slot (either one) and work . . .

There can be upto 254 games loaded into the MGC, however, due to a number of games requiring 2 x 16K blocks, the actual number of games will be less. Currently I have achieved 178. You can choose the Games you want from an ever growing list - see the instructions below.

Software:
The MGC comes with a pre-installed Menu program. This will allow the user to list All the games, in pages of 17, or to search, and list, Games Alphabetically, by Publisher or by Genre from a pre-defined list.

There is also a suit of Utilities, to enable loading or removing the contents.

Acknowledgements:
Martin Barr, who converted his EEPROM utilities to work with the MGC. These are embedded within the Cartridge.
Ian Tomlinson, who designed the very professional MGC Label.
Jonathan Harston, for assisting me with various BASIC questions and providing a m/c FN call to speed-up the search and display routines plus the very fast ROMFS loader.
Jason Nicholls, who provided the m/c display and search routines.
David Boddie, for all the Game conversions including the compression code which reduces some games from two 16K blocks to one. The de-compression code also speeds up the game loading considerably!
Richard Toohey, for a utility to automate the Index creation. I can now do the Index creation in seconds! It took several days to do this manually
Plus everyone who knows me who has contributed with helpful hints, tips and encouragement.

Schematics:

Retro Hardware MGC - 05-04-17.PDF

- Last updated 05-04-17

(288.33 KiB) Downloaded 126 times

MGC Utilities Save Program:

Save MGC Utilities.ssd.zip

(1.2 KiB) Downloaded 80 times

MGC User Guide:

MGC User Guide 1V0.docx.zip

- Last updated 30-07-17

(1.42 MiB) Downloaded 75 times

MGC Games Selection Template - Now Supports Utilities and Applications!

- Support from 09-04-17

MGC Game Selection.xlsx.zip

- Last updated 14-07-18

(40.42 KiB) Downloaded 24 times

Please follow these guidelines:

1) Download the "MGC Games Selection Template" (above - Excel Spreadsheet!).
2) Rename the spreadsheet using Your Name
3) DO NOT ALTER THE SPREADSHEET IN ANY WAY OTHER THAN AS DESCRIBED BELOW
4) Deselect games you DO NOT WANT by entering a 0 (zero) in column N against the game.
       E.g. If you don't want 3D Dotty enter a 0 (zero) into cell N2
5) Carry on deselecting games until the RED cell changes to GREEN and indicates a number less than 255.
6) Return the final spread sheet to: retro hardware AT dave ej hitchins DOT plus DOT com

You can maximise the number of games you get by choosing SINGLE ROM games first! The maximum number of ROMs is 254.

Quick Start Guide: Insert the MGC into either cartridge slot - Power-up with the shift and space key held down

[CMcDougall]

Boffin1 -Addictive : does not work on an elk, but does work on a master.
Boffin2 -Addictive : does work on elk, and needs fiddled to work on master.

Spy Hunter -US Gold : does not work on a elk, and needs fiddled to work on master.
Sim -Viper : does not work on a elk, and needs fiddled to work on master.

my guess on your new project, is a plus1 Super Cart, throw a SD /MicroSD /MMC in it, and acts like the mmBeeb interface

[daveejhitchins]

Boffin1 -Addictive : does not work on an elk, but does work on a master.
Boffin2 -Addictive : does work on elk, and needs fiddled to work on master.

Spy Hunter -US Gold : does not work on a elk, and needs fiddled to work on master.
Sim -Viper : does not work on a elk, and needs fiddled to work on master.

my guess on your new project, is a plus1 Super Cart, throw a SD /MicroSD /MMC in it, and acts like the mmBeeb interface

Well, the super cartridge is correct . . . But it works out a lot easier than having to use any of the parts you've mentioned - So far I can handle 64 games They'd work from the ROM filling system like Snapper etc. Select the game you want - Shift-Break and off you go. The important thing here is the cost - Around a tenner! - Hopefully under - probably

Hence the need to know Game sizes and if they work on the Electron or Master or Both. There will be a switch to select the Elk or Master which would give 32 Games each or all 64 on either machine.

Dave H

[dixiestoat]

Ooooo.... We like the sound of that....
Something else to add to your growing list, but a big YES PLEASE!! from me...!

[richardtoohey]

Sounds interesting, Dave.

But don't have any useful list of game sizes like that, sorry.

What would be a good starting point - a bunch of SSDs that work on both Electron and Master? Sounds like it could be games that work on either?

Could start with Acornsoft & Superior & Micropower games and size them up.

[daveejhitchins]

Looks like I'll have to rope-in some testers . . . Now who uses a Elk, likes games, lives not too far away and goes by the name of Sydney? Hmmm . . . New Zealand's not that distant either

Dave H

[richardtoohey]

I can certainly help with games testing!

Will have to be on emulators, though, for a while, because I'm about to set off on my travels again.

But I can certainly fire up Elkulator and Beebem (Master mode) and start getting a list of games together (like I said, might be easiest to start with some of the bigger software houses - more likely to have Master-compatible software.)

Then I can give you some indication of titles and sizes. Would that help?

[richardtoohey]

Next question - would it be safe to assume PAGE is going to be &E00 for both platforms? I'm just thinking about any games that move stuff around in memory.

I think ADFS on the Electron would be &1D00 or something like that - so any images I look at might have code to move &1D00 to &E00 or something like that (some of them would move the code even lower, so the code would still be needed.)

The moving code wouldn't hurt anyway, just thinking out loud about PAGE assumptions for something like this - might not be anything at all to consider ...

[dixiestoat]

I am always up for some Elk games test driving! Count me in..!

[aerworuld]

Yep, Elk and I are ready for testing too!

[daveejhitchins]

Yes, Yes and Yes, Please ^^^

You can assume that Page can be set to E00 as we'll be using the ROM filing system. To prepare the games - if they aren't already ROMed e.g. Snapper etc. (Not sure just how many ROM games there were?) then we can use *MakeROM. This is available in both the ABR Utilities and the Advanced ROM Manager. Here's the text for the utility:

Code: Select all

MakeROM

This program is used to frame one or more files in a Rom Filing System image, for loading from a RAM bank (like the way these utilities were supplied).

The Rom Filing System is activated by *ROM, and behaves like the Tape system, except that only reading is permitted.

This program is a Sideways RAM image, and must be loaded into a RAM bank using *LoadROM.

Start the program with *MakeROM or *PMakeROM. Either form of the name may be abbreviated by putting a full stop after the characters.

The program can only be run in the host processor, so Second Processor users should run this program with the Tube off. If a Tube is active the program will refuse to respond to *MakeROM/*PMakeROM.

Once the program has been started it will ask you for a title for the image about to be created. This name will appear on *ROMS as the title of the ROM, and will also appear on *HELP. It can be up to 20 characters long, and should only include alphanumeric characters.

You will then be presented with a list of options to choose from, which are:

	T	Select Tape and then load a file
	D	Select DFS and then load a file
	A	Select ADFS and then load a file
	R	Load a file from current filing system
	*	Operating system command
	F	Start a fresh image
	S	Save the current image
	Q	Quit the program


Options T, D and A will select the relevant filing system, and then ask for a filename. (R just asks for the name, keeping the current filing system). The filename must be just a filename, of one to ten characters. It cannot include any kind of directory specification or other special characters.

The file will then be read and converted into ROM filing system format. An error message will be displayed if the file would cause the image to overflow, and the file will not be included.

Once the conversion has been completed or aborted the option list will be displayed again.

* is provided for Operating System commands to be entered. Care should be taken that memory is not corrupted, otherwise the image being built may be overwritten. When the OS command has completed, press the RETURN key and the option list will be displayed again.

F starts the program again with an empty image. The program will ask you to confirm that you want to start afresh by pressing Y. Press ESCAPE if you have second thoughts.

S saves the image to the current filing system. You will be asked for a filename.

Q leaves the program. You will be asked to confirm that you want to leave by pressing Y, or ESCAPE if you have had second thoughts. When you leave MakeROM you will be returned to BASIC.

The image produced by this program may be loaded into a RAM bank by using *LoadROM.

Normally files in a ROM filing system image cannot be executed with *name but must be run with */name or *RUN name. Images produced by this program will permit programs to be run by *name.

It is possible to have a !Boot file in an image which can be started by SHIFT SPACE BREAK. However, this program must be in machine code, and is called before BASIC is started. To make the facility more useful, a program called !Boot is included in the ABR. This program starts up BASIC and then CHAINs a program called BOOT. Thus to set up an auto-boot sequence you should include the !Boot provided and a BASIC program BOOT of your own.

So, as long as we can get the game and, preferably the 'loading' screen, into a 16K block (we'll need a little extra for the !Boot file and any other space that MakeROM needs) then everything should work fine.

If we gather 'lots' of games then there's the option of using the Second 16K Bank, of the Cartridge slots and having 128 Games Or would that be too much

The real limitation, as I see it now, is getting the list on the Cartridge I came to the conclusion, early this morning, that it would have to be a good piece of card with all the details on . . .

So, we need to keep a 'running' list of who's doing which games, to prevent duplication. I'll keep a spreadsheet (or would someone else like to do that?) of where we are. I'll start the ball rolling with SNAPPER and HOPPER

Of course we can work from this list - should be enough to keep everyone going

Dave H

[richardtoohey]

That's quite a list

I can see my Acornsoft/Superior plan isn't too good - because Superior took over the Acornsoft titles, so it won't be clear cut e.g. Codename: Droid (Superior Software/Acornsoft)

How about I put my hand up for the Micropower titles? I'll go through and see how big the Electron version is, and whether there is a Master version, etc.

A bit of R&D like that should give some indication as to sizes (I think some loading screens would push you over the 16K limit quite easily - the BBC B versions of games often had a graphics loader)

But I can get started and see how it goes.

It will be over the course of the week, though - don't wait up for my results!

[sydney]

Happy to help, though I'm no longer an elk user. Funds got a bit tight and the elk's had to go as I'd just stopped using them. All I have now is a master and a beeb.

[aerworuld]

Happy to help, though I'm no longer an elk user. Funds got a bit tight and the elk's had to go as I'd just stopped using them. All I have now is a master and a beeb.

[CMcDougall]

prepare the games - if they aren't already ROMed e.g. Snapper etc. (Not sure just how many ROM games there were?)

the official game carts are here, scroll down a bit:
http://www.stairwaytohell.com/roms/homepage.html
would also like to be a tester for the elk (don't have Master, but have Compact), as it gives me an excuse to grab one of my three elks and plus1 from my other house, and have here, sure wife will be well pleased
BITD, I had 2 carts, with four 16k chips that I programmed for the elk, being Dare Devil Denis, Chuckie Egg, Munchyman & Super Pool using the RFS system. Will try and find the images, but some where >16k, so some files spread across 2 eproms.

Chuckie egg elk version works on a beeb, so presume does also on a master. Think only the text colour is different, not the speed of play.
Also Dare Devil Denis and Super Pool.

Got it wrong earlier , Boffin2 does work on elk & master, it's only Boffin1 that needs fiddle for master, but not at all on elk

Should of jotted down what beeb games did not work on mCompact last night when I was playing it

[daveejhitchins]

Happy to help, though I'm no longer an elk user. Funds got a bit tight and the elk's had to go as I'd just stopped using them. All I have now is a master and a beeb.

Simon . . . You'll be good-to-go for the Master then?

Dave H

[aerworuld]

What can I best do to help then Mr H? Point me in the right direction and im there

[daveejhitchins]

What can I best do to help then Mr H? Point me in the right direction and im there

Well, it looks as if Richard is going to handle the MicroPower titles - So how about you tackling the Acorn Titles? Have you a RAM cartridge or Sideways RAM of any sort? If you have than I can sent you the ABR Utils - with MakeROM (if you haven't got them already?) - and you could test them out as they would be used!

Dave H

[aerworuld]

What can I best do to help then Mr H? Point m in the right direction and im there

Well, it looks as if Richard is going to handle the MicroPower titles - So how about you tackling the Acorn Titles? Have you a RAM cartridge or Sideways RAM of any sort? If you have than I can sent you the ABR Utils - with MakeROM (if you haven't got them already?) - and you could test them out as they would be used!

Dave H

I think I can make a change to my EUP board to accommodate that though cant I? Or am I at a stage where I can negotiate some pocket money from the missus to purchase an ABR board from your good self?

Stuart

[Garrettimus]

Awesome, Dave!

[daveejhitchins]

I think I can make a change to my EUP board to accommodate that though cant I? Or am I at a stage where I can negotiate some pocket money from the missus to purchase an ABR board from your good self?

Stuart

You can indeed use your EUP . . . Check first though for RAM corruption! It only affected a few certain combinations of Elk and Plus 1s and, MartinB added a mod to fix it.

Dave H

[dixiestoat]

Must say, I love the idea of this,

Maybe the first run could be like Elk's Greatest Hits..?

Maybe run 2 (here's hoping..?), could be for the more obscure, unusual ones..?

Thats my thoughts anyway..!

[aerworuld]

how about you tackling the Acorn Titles?

I can sent you the ABR Utils - with MakeROM (if you haven't got them already?) - and you could test them out as they would be used!

Dave H

yep yep! i'll jump on it when i'm equipped in true Squirrel style

[CMcDougall]

any pictures of this cart yet Dave, does it run totally PC free, or using the PC/laptop to send the files , must be some 'eeprom' with 16k*64games = 1024k
found some of my old files on disc image for the elk :

.ssd below of these:

CMroms67elk Hunchback SuperPool DDDenis.zip

ssd

(18.11 KiB) Downloaded 117 times

just tried in Master mode, and only SuperPool works correctly, but all work on the elk perfect .
don't know where ChEgg, Munchyman & ?? is on other cart, must of ran out of disc space BITD, but will image them next week....

[daveejhitchins]

any pictures of this cart yet Dave, does it run totally PC free, or using the PC/laptop to send the files , must be some 'eeprom' with 16k*64games = 1024k

No pictures, it's still in the idea stage at the moment. I have the circuit sorted, on paper, at least. Yes, It's a Big ROM - Quarndon have them here - Limited number! I'll have to see if I can find more. It'll need programming externally - I'll add a connector to program in-situ on the board. To get the 128 games we'll need 2 of these. So I might make provision, at least.

Dave H

[richardtoohey]

So, as long as we can get the game and, preferably the 'loading' screen, into a 16K block (we'll need a little extra for the !Boot file and any other space that MakeROM needs) then everything should work fine.

OK, so what happens if we can't get into 16K?

I've taken the Bumble Bee UEF from the Stairway To Hell Electron section, and I have

Code: Select all

BUMBLE 1C 1C40 00001900 00008023
BEE    23 2400 00000900 00001FDF

So sizes are &1C40 + &2400 = &4040 ... just over the &4000 we have for 16384, and no room for a !BOOT. Do double-check my numbers in case I am reading the wrong columns and/or adding up incorrectly!

BUMBLE is a graphical loader and has joystick configuration, BEE is the main program (loading at &900 - does that cause ROMFS any issues?)

In this instance, do we say "try the next game" (I'll look at Cybertron Mission next) or do we try and carve off some bytes, or what?

What's the plan, StanDave?

EDIT: Cybertron Mission is easier, size-wise - no graphics logo in the loader:

Code: Select all

CYBERTRON 0B 0B35 00000E00 00008023
CYBERTRON 27 2800 00001900 00004000

So, if I'm adding up the right columns, we come in at 13,109 bytes.

But Cybertron Mission raises another question - does ROMFS mind two files of the same name (CFS is fine)? Both the loader and the main program are called CYBERTRON.

Lots of stuff to learn about, lovely!

[sydney]

I'm happy to help on the master, I do have a couple of concerns though.
1. Copyright.
OK, no one seems to mind a large, freely accessible database of ssd's full of bbc micro games but someone might have a problem with cartridges choc full of games being sold at a profit - no matter how small that profit is.
2. mmbeeb.
On the master mmbeeb is cheap, popular and more flexible than a cartridge. Is there actually any need for master compatibility? Would you be better off devoting all of the space to elk games where the only mmc solution is gommc?

[richardtoohey]

Copyright is definitely something not to be dismissed lightly, but not sure your argument entirely stacks up.

A copy is a copy, regardless of the medium - an SSD on the internet, a disc from a "friend", a version you've put on a ROM. You don't have the right to copy.

In some ways the cartridge/ROM solution is "better" because you are very obviously limiting yourself to a very small market - people will have to have physical machines, with ROM sockets (so a Plus 1 on the Electron). The number of people in that position will be less that the number of people using an SSD on a real machine (or more likely an emulator.) Trying to sell a CD with emulators + thousands of games is a more blatant breach of copyright, so that might be "worse." But again, however you are doing it, you are copying something you don't have the right to copy.

IANAL but I can't see any copy is really going to be any better or worse than what is already on the internet.

[EDIT - having re-read what you said I think the point you are making is more to do with the price/profit motive ... but going by Dave's previous retro-projects, he is definitely not going to be making any money out of this.]

[sydney]

I agree that a copy is a copy, it's the sale that is the problem. Free downloads of obsolete stuff are probably ignored because there is no money involved. As soon as money enters the equation copyright owners will want their cut. It's no more nor less legal it just gives them a reason to object.

EDIT: I agree that Dave won't be making much (any) money but the men in grey suits might not see it that way.

[richardtoohey]

Oops, my edit (where I got your "for sale" point) missed your new post.

I can't answer the legal questions, but fun to be involved on the technical side, anyway.

And "testing" some of these games is demanding ...

Cybertron Mission seems quite sedate compared to the Beeb version.