28-pin 27C512 EPROM into 24-pin socket?

[ukretro]

I recently received a HDB-DOS ROM which arrived programmed onto on a 27C512 EPROM.

I *had* intended to re-purpose a Meteoroids cartridge as a DWDOS cartridge to save loading up a WAV file each time I powered up the Dragon but on opening it up, found the cartridge had 2 x 14-pin sockets with the game burned to a TMS25P32JL 4k EPROM.

I've searched for a data-sheet for the Texas Instruments TMS25P32JL EPROM but so far, I've turned up nothing.

Is it possible to make a ROM adaptor to allow me to plug the 28-pin 27C512 into the 24-pin socket on the Meteoroids cartridge? Will a Dragondata cartridge work with the 27C512 (better yet, a 27C64)?

If not, is there another way to utilise the DWLOAD EPROM in cartridge form on my Dragon?

Edit: Would THIS work? If not, does anyone still make Dragon-compatible cartridge boards which would take a 27C512?

[tormod]

I recently received a DWDOS ROM which arrived programmed onto on a 27C512 EPROM.

HDB-DOS ROM, I believe

I *had* intended to re-purpose a Meteoroids cartridge as a DWDOS cartridge to save loading up a WAV file each time I powered up the Dragon but on opening it up, found the cartridge had 2 x 14-pin sockets with the game burned to a TMS25P32JL 4k EPROM.

I've searched for a data-sheet for the Texas Instruments TMS25P32JL EPROM but so far, I've turned up nothing.

Is it possible to make a ROM adaptor to allow me to plug the 28-pin 27C512 into the 24-pin socket on the Meteoroids cartridge? Will a Dragondata cartridge work with the 27C512?

Yes, that will probably work as long as the necessary address line for a 8KB ROM is routed to the cartridge. Since the original ROM is 4KB you cannot be sure without checking. You should be able to check this with a multimeter. Check that the pin A12 on the cartridge edge connector is connected to pin 21 on the 24-pin socket. While you're at it, you can check all the other lines too, to make sure the TMS25P32JL didn't have a non-standard pin layout.

If not, is there another way to utilise the DWLOAD EPROM in cartridge form on my Dragon?

Edit: Would THIS work? If not, does anyone still make Dragon-compatible cartridge boards which would take a 27C512?

Yes, that will be pretty much the same adapter as the one I offered you for the Dragon 32 ROM in private mail. I can tell you it is a pain to solder though

You will have to make sure the extra address lines on the 27512 (64KB) EPROM is tied to the correct level, unless you have the same in all 8 of the 8KB banks.

[munkeyboy]

Hi, I know that the Super Dragon Writer II cartridge from Dragon Data has 2x 28 pin ic's (2764's I think).

I will try and locate the cartridge and take some pictures later.

Here is the data sheet you were after.

Hope this helps, Gareth.

[ukretro]

Here is the data sheet you were after.

Thank you. That'll help when it comes to getting this together.

[ukretro]

I recently received a DWDOS ROM which arrived programmed onto on a 27C512 EPROM.

HDB-DOS ROM, I believe

You are indeed correct. HDB-DOS. It was early when I wrote this (That's my excuse and I'm sticking to it). I'll go back correct my original post.

Yes, that will probably work as long as the necessary address line for a 8KB ROM is routed to the cartridge. Since the original ROM is 4KB you cannot be sure without checking. You should be able to check this with a multimeter. Check that the pin A12 on the cartridge edge connector is connected to pin 21 on the 24-pin socket. While you're at it, you can check all the other lines too, to make sure the TMS25P32JL didn't have a non-standard pin layout.

With the help of the datasheet Munkeyboy has attached, I'm hoping to make sense of this.

Yes, that will be pretty much the same adapter as the one I offered you for the Dragon 32 ROM in private mail. I can tell you it is a pain to solder though

I probably spend 3-4 hours a day soldering ATM. Hopefully, I should be able to pull this off without destroying something.

You will have to make sure the extra address lines on the 27512 (64KB) EPROM is tied to the correct level, unless you have the same in all 8 of the 8KB banks.

I was thinking of copying the contents of the ROM you sent to a smaller EPROM. As the HDB-DOS code is only 8KB, I might burn it to one of my spare 27C64 EPROMs.

[tormod]

Yes, that will probably work as long as the necessary address line for a 8KB ROM is routed to the cartridge. Since the original ROM is 4KB you cannot be sure without checking. You should be able to check this with a multimeter. Check that the pin A12 on the cartridge edge connector is connected to pin 21 on the 24-pin socket. While you're at it, you can check all the other lines too, to make sure the TMS25P32JL didn't have a non-standard pin layout.

With the help of the datasheet Munkeyboy has attached, I'm hoping to make sense of this.

Yes, that will be pretty much the same adapter as the one I offered you for the Dragon 32 ROM in private mail. I can tell you it is a pain to solder though

I probably spend 3-4 hours a day soldering ATM. Hopefully, I should be able to pull this off without destroying something.

Note that the ROM-EPROM adapter in the uwaterloo link you gave (and my Dragon 32 ROM adapter) is for a 24-pin ROM socket and not for a 24-pin EPROM socket! I should have pointed that out in my first reply.

A 24-pin EPROM to 28-pin EPROM adapter is different from a 24-pin ROM to 28-pin EPROM adapter. As you can see by comparing the TMS25P32JL datasheet with the pin list in the uwaterloo link. Since you have an EPROM burner it would be easier to burn HDB-DOS to a 28-pin EPROM compatible with your cartridge.

Alternatively you can order new cartridge boards which will fit a 64Kb-512Kb EPROMs, see http://www.nf6x.net/2013/10/cocoeprompak/ He writes that he didn't test 512Kb yet though.

[munkeyboy]

Hi, I found that a lot quicker than I expected, here are the Super Dragon Writer cartridge pics as promised.

[ukretro]

Hi, I found that a lot quicker than I expected, here are the Super Dragon Writer cartridge pics as promised.

Thanks for digging the cartridge out. Yes, they take 27C64 EPROMs which would be a direct fit for the HDB-DOS image I've just burned to an Intel D2764-3 EPROM, as pictured.

It'll probably be easier to pick up one of the OSHPark cartridge boards though, than wait for a Dragon SDW cart to show up on eBay.

I actually have a Green board *like* the one at OSHPark. I bought it a few years ago, shortly after I got my Dragon 64 I'm not likely to locate it any time soon though. Pity really; I've been moving it around for ages and now I need it, I can't put my hands on it. I guarantee it'll turn up AFTER I've bought one from the link above.

You know, I also have a Dragon32 floppy drive and interface hiding around the house somewhere, too. Why I can never locate these things when I need them is a mystery.

[ukretro]

Since you have an EPROM burner it would be easier to burn HDB-DOS to a 28-pin EPROM compatible with your cartridge.

I've just transferred the code to a 2764 (which is also unfortunately 28-pin).

Alternatively you can order new cartridge boards which will fit a 64Kb-512Kb EPROMs, see http://www.nf6x.net/2013/10/cocoeprompak/ He writes that he didn't test 512Kb yet though.

I've registered but they seem quite slow at sending the account creation confirmation email, so I don't yet know how much the boards are.

Now if I could only locate the cartridge board I bought a while back...

[ukretro]

I just located my "Coco/Dragon 32K EPROM Cartridge" board.

it has a copyright of 2010 and was sold by GIMEchip though visiting the site now, there's no reference to this board.

It has a part no. CC1-32KEC-0001.0

It's a tiny board with holes for an IC socket, a jumper (JP1) and (I think) a capacitor but due to lack of references, I'm not sure.

I'll add a picture once I've soldered in the socket.

It's surprising what you can find when you're determined enough to turn your "retro-room" upside down!