9 replies to this topic

[gusbucket13]

Is it theoretically possible to download freebie demo code off the internet such as available at the Jagudome and instead of using the BJL to download it into the BJL EProms - to burn it into a CD?

Well yes I know you can physically do that bit. But would the CD play on a standard Jag CD then? (If you had a bypass cart in the cart port) if not what would you have to add to the code to make it run before you burn it on to the CD?

You have to manually port the code to a specific start address on the BJL EProm, will a Jag CD do that automatically?


Cheers
Chris C
Always testing the impossible

[atarifan49]

Yes it's possible. The Native demo disk that Songbird provides with Protector SE does exactly that.

The Native game is loaded from CD into the Jaguar's main memory and starts automatically. The only thing that is needed is one of the CD bypass schemes (Protector SE, Battlesphere Gold, or B&C's CD Bypass) to load the disk.

As long as the game doesn't require use of memory that resides in the cartridge area (memory addresses $800000 - $CFFFFF). The game has to be specifically written to run from the Jaguar's 2meg of DRAM memory. Otherwise you need to have a Alpine or Flash cart to run the program.


Glenn

[gusbucket13]

I tried today to burn an unencrypted downloaded Jag demo on to a CD and use the Protector SE encryption bypass to run the CD, it appeared to all work well except the CD just kept spinning and spinning with a blank screen like its looking for a reference point to start running the program which it cant find, - bum oh well 50c wasted!

I now understand that with anything CD youre limited to the Jags onboard DRAM 2mb - so in effect you have less capacity than a 4 Mb game cart even though the CD has 650mb of storage space, cos on a cart the jag can use some of the spare memory in the cart - but it cant use it in the CD - Is this a correct understanding of the limitations?

Surely the question that cries out then is - is there a way to increase the Jags DRAM capacity without too much major surgery, like was done for the Co Jags?

Lastly what are the ROM chips that are in short supply for new carts? (designation and equivalents) Perhaps there may be quantities in the UK or Europe as yet untapped? It shouldnt hurt to look -

Cheers
Gusbucket13

[Matthias]

Hi!

gusbucket13 said:

I tried today to burn an unencrypted downloaded Jag demo on to a CD and use the Protector SE encryption bypass to run the CD, it appeared to all work well except the CD just kept spinning and spinning with a blank screen like its looking for a reference point to start running the program which it cant find, - bum oh well 50c wasted!

I think you just forgot to turn the homebrew-file (*.JAG?) into a valid JagCD-track using one of the Atari-developers tools.

Quote

I now understand that with anything CD youre limited to the Jags onboard DRAM 2mb - so in effect you have less capacity than a 4 Mb game cart even though the CD has 650mb of storage space, cos on a cart the jag can use some of the spare memory in the cart - but it cant use it in the CD - Is this a correct understanding of the limitations?

Yes. But you can play audio tracks and Cinepak-movies from CD

Quote

Surely the question that cries out then is - is there a way to increase the Jags DRAM capacity without too much major surgery, like was done for the Co Jags?

Don't think so. The CoJags had an enhanced PCB.

Quote

Lastly what are the ROM chips that are in short supply for new carts? (designation and equivalents) Perhaps there may be quantities in the UK or Europe as yet untapped? It shouldnt hurt to look -  

Cheers
Gusbucket13

No. Even 8bit-versions (we would like to use 16bit-chips for the Jaguar)
aren't as cheap as they were before the Mobilephone-hype.

Regards
Matthias

[LinkoVitch]

Matthias said:

No. Even 8bit-versions (we would like to use 16bit-chips for the Jaguar)
aren't as cheap as they were before the Mobilephone-hype.

So any EPROM will do? if that is the case then they are pretty cheap at Maplin. and 8MB EPROM is only £9.99 (which I guess is around $15)

The smaller 512K ones are £2.49 ($3-4)

[Matthias]

LinkoVitch said:

Matthias said:

No. Even 8bit-versions (we would like to use 16bit-chips for the Jaguar)
aren't as cheap as they were before the Mobilephone-hype.

So any EPROM will do? if that is the case then they are pretty cheap at Maplin. and 8MB EPROM is only £9.99 (which I guess is around $15)

The smaller 512K ones are £2.49 ($3-4)

Depends on your PCB:
There are two original Atari types available:
1) the 2 16bit-chip PCB and
2) the 4 8bit-chip PCB.
At the end, both offer a 32bit-bus (2*16=32 and 4*8=32), and don't have addresslines a0 and a1 connected to the DIP-sockets.

For images of current games i would keep the 32bit-bus because
these programs might need the access-speed.

But if you write your own games, you could use a self-designed card
with only one 8bit-socket (with addresslines a0, a1....).

There is one new commercial (mass produced) design known: The Songbird cards.
Instead of DIP-types they use PLCC.

Cheers
Matthias

[LinkoVitch]

They don't seem that expensive. I have only found 8-bit ones. But 4 256K 8 bit 120ns EPROMS are 3.99 each so 4 would only be £16 is (probs around $22) Dosen't seem too expensive

http://www.maplin.co.uk

goto semiconductors and then eproms.

They have a few.

[gusbucket13]

One has to congratulate Carl at Songbird for going the extra mile and getting the new cart boards designed and made, presumably the EPROM chip they are designed to use is a more common and therefore cheaper example? I wonder if Carl will be gracious enough to let others buy into the product of his labours and buy blank boards from him for new game development work?

Anyway on a different note - Best electronics list some EPROMS too the 27C512 at $6:50c the 27C010 (1 meg) at $8 and the 27C101 (also 1 meg) at $10 other ones which are probably the proper ones for the Jag carts are listed as Call for price - which always seems to be a euphamism for bloody expensive!

Hope this helps in some small way

Cheers
Gusbucket13

[Stone]

A little clarification on which EPROMs can actually be used...

Like Matthias said, there's two Atari - designed cart PCBs which can be used, the 4MB (2x2MB chips) and the 2Mb (4x512KB chips).

The 4MB one is designed for the 27C160 (as in the BS carts) which is astonishingly expensive as they aren't used for anything much any more, and are in correspondingly lower production (unless it's been stopped altogether and old stock is all the remains...I'm not sure on this point). Expect to pay around £27 each at Maplin (don't recall the exact price).

The 2MB one is slightly more versatile, but you are restricted to chips currently in production, which rules out the Toshiba one (27C4000D?). The 27C040 will work in this board, and the 29C040 Flash chip will if you have one of the jumper-selectable PCBs (the pinout is slightly different).

If you have an EPROM burner and a UV lamp to erase them with you could get a good deal off eBay - I got 10x27C040 for about £10 all told, so look around.

To find out exactly which chips are supported, go download the Jag Developer's Manual off Starcat's site (http://www.atari-jaguar64.de) - the section you want is called Hardware Reference (I think...it could be in the Technical Reference). Just download it all, it's some interesting shiznit

If you want to design your own PCB that's also possible. Just don't expect it to be easy It looked to me from the commercial cart PCBs (which differ from the EPROM ones btw) like the Jag cart port was designed with certain chip pinouts and cart layouts in mind, as all the tracks are pretty much lead straight down to the port which can't be a coincidence

Anyway, enough babble from me, go build something interesting

Stone

[gusbucket13]

Just a thought to be tossed into the arena - has anyone tried Russia as a source for cheap chips - they are definately a lot cheaper and they might have older type chips still in production.

The only problem would be deciphering which is the equivalent of what.

They do exist, I spent several hours scouring the internet late last week, and established at least that much, just most electronic component suppliers lists on the internet charge a subscription fee just to view the sources and the equivalents datalists.

It is acknowledged by most that whilst optically inferior they are every bit as good as western originals in electronic function & performance.

Cheers
Gusbucket 13