how to install fourth eprom

[w1k]

hi, my atari have maybe 15 years old hw modification (3x different cartidges inside three eproms)

i want install new eprom, with q-meg 5rc1.. it is possible?

 

 

Edited August 11, 2010 by w1k

[Rybags]

Cartridge Eproms would stack on top of the Basic ROM.

 

That's a QMeg OS isn't it? In that case, it has to piggyback the OS ROM.

 

Or you could just buy a readymade upgrade like the 32in1.

[w1k]

yes, but that eprom are rare eproms with slovak carts..

[classics]

 

I love this picture. It looks like something has taken up residence in your XE and is sucking the life out of it.

 

Steve

[Rybags]

In theory, you'd have a switch that supplies +5V to /CS and /OE of one chip while feeding the normal /CS to those pins of the "active" chip.

 

That's of course assuming that the EPROM there is a drop-in OS replacement on your machine.

Edited August 11, 2010 by Rybags

[Defender II]

yes, but that eprom are rare eproms with slovak carts..

 

Very nice. You can make an OS board and just add a switch to select which one you want before you power on.

If you use sockets then your nice chip will be kept like new. I am sure there are instruction on making an OS board on here somewhere. I have made my own in the past so if you can't find instructions I can find mine.

 

What slovak carts do you have? Do you have any you might sell?

[BillC]

The multiple OS choices:

 

Option 1: Stacked chips with /CS and/or /OE switched and all other pins connected in parallel, this is what you already have. Involves a lot of soldering, with a risk of damaging an EPROM.

 

Option 2: A circuit board which does the same electrically as the stacked chips option. This spreads the chips out horizontally, more expensive than option 1 but allows chips to be swapped. These type of boards used to be available commercially from Newell and other third party OS suppliers.

 

Option 3: A 27256/27512 EPROM containing 2 or 4 OS's and using A14/A15 to select the operational 16K bank. Other than the wiring/switches no additional space is used, if the OS chip is socketed no soldering is required except for A14/A15. This basically combines option 1 or 2 into a single chip. An EPROM programmer is needed to read/save the original chips contents, which would then be combined into a single file and programmed into the 27256/27512.

 

Option 4: A flash ROM OS upgrade, like the Atarimax 32-in-1 or the Candle Ultimate 1MB upgrade(still under development). According to Candle the Ultimate 1MB upgrade will be user flashable, which I don't believe to be true for the Atarimax upgrade.

 

 

 

You could use option 3 to replace the socketed EPROM at the top of your stack allowing you up to 6 OS's, although you would probably want to isolate pins 2 and 27(A15/A14) of the new EPROM from the 27128 EPROM lower in the stack.

[w1k]

thanks for information, today i must look for that, modification take my father..

 

dumps from eproms are here:

http://atari8.podstromami.com/projekty/

 

"Vydumpovanie internych cartridgov do suboru – hotovo"

[Rybags]

Option 3 - easiest to just use an image that's already out there rather than dumping your own.

 

Then it's a case of which version of the XL/XE OS... personally I'd take the default 800XL one (Rev 4?)

 

But if I was going to the trouble of burning a multi-OS EPROM, I'd customise it first... possibly get rid of Attract Mode, change the default key repeat rate, and maybe throw in a few other enhancements.

 

One of these days... I'll write some sort of patcher. You also need to fix the Checksum bytes if you mod the OS.

[flashjazzcat]

Option 3 - easiest to just use an image that's already out there rather than dumping your own.

 

Then it's a case of which version of the XL/XE OS... personally I'd take the default 800XL one (Rev 4?)

 

But if I was going to the trouble of burning a multi-OS EPROM, I'd customise it first... possibly get rid of Attract Mode, change the default key repeat rate, and maybe throw in a few other enhancements.

 

One of these days... I'll write some sort of patcher. You also need to fix the Checksum bytes if you mod the OS.

By what algorithm are the checksum bytes generated?

Edited August 12, 2010 by flashjazzcat

[Rybags]

Just add each byte together, but without adding the carry back in like SIO does.

<ed> It's a 16 bit checksum.

 

Looked at the source - the Self-Test area is entirely checked, for the main part of the OS the checksum bytes themselves are (obviously) excluded ($C000-1 and $FFF8-9)

Edited August 12, 2010 by Rybags

[+skr]

According to Candle the Ultimate 1MB upgrade will be user flashable, which I don't believe to be true for the Atarimax upgrade.

 

It is true for the Atarimax. You just need an 8Mbit flash Cartridge, no need even for the programmer. I already flashed my own 32-1 with the Atari itself and the freely available MaxFlash Studio Software from Atarimax. Tricky part is the creation of the ROM-file containing the ROMs, but as far as I understand Steven is going to make it public available.

[Rybags]

So, you take the chip from the 32in1 and put it in the cartridges socket to do the operation, I take it?

[+skr]

So, you take the chip from the 32in1 and put it in the cartridges socket to do the operation, I take it?

 

There are two chips in the cartridge. Just flash them and put one into the 32-in-1 OS. Put the "old" OS chip into the cartidge, and you still have a full working cartridge which you can flash with whatever you like. It´s that easy.

Edited August 12, 2010 by skr

[+Roydea6]

One of these days... I'll write some sort of patcher. You also need to fix the Checksum bytes if you mod the OS.

By what algorithm are the checksum bytes generated?

Here is a basic program to run the OS checksum from basic.

http://www.atariage...._1#entry2007564

 

First checksum is the first two bytes of the OS and the seccond checksum is near the end of OS.

If you do this on an Emulator the patches need to be turned OFF (i.e) SIO,PRINTER,H:DRIVER. This program just calculates the proper checksum, but does not patch the OS.

Edited August 12, 2010 by rdea6

[BillC]

According to Candle the Ultimate 1MB upgrade will be user flashable, which I don't believe to be true for the Atarimax upgrade.

 

It is true for the Atarimax. You just need an 8Mbit flash Cartridge, no need even for the programmer. I already flashed my own 32-1 with the Atari itself and the freely available MaxFlash Studio Software from Atarimax. Tricky part is the creation of the ROM-file containing the ROMs, but as far as I understand Steven is going to make it public available.

 

When I said the Atarimax 32-in-1 wasn't user flashable, I meant in-circuit. When the Ultimate 1MB upgrade is released, Candle is supposed to have a utility to reprogram the flash ROM without having to remove it from the system, similar to the intSDX upgrade.

 

Having to remove the flash ROM to reprogram basically removes all of its benefits over an EPROM except not having to erase it before reprogramming. You still have to open the system, remove the chip, put it in a programmer(whether it's an Atarimax 8Mbit flash cartridge or a full EPROM/EEPROM programmer) and reprogram it, then put it back in its socket and reassemble the system.

 

People with the Atarimax upgrade will probably not reflash once they have it set up the way they wish, 32 OS's give a lot of options.

 

Reprogramming the flash ROM in-circuit is a desirable feature in the Candle upgrade, because it allows easy updating of the internal SpartaDOS-X and also changing which 4 OS's are installed.