Burned First EPROM but have Questions About Dual OS

[simondo]

I managed to burn my first EPROM today, Parados onto a 27C512 EPROM and fitted it to my DDI-1....and it works!

I am lucky enough that at work I have a Dataman 40Pro programmer and access to a couple of EPROMS and an EPROM eraser.

For best compatibility I would like to burn Amsdos/Parados to same EPROM in my DDI-1 and switch between the two. Does the method for Dual OS as described here DualOS - CPCWiki work for the DDI-1?

Although I have a 40025 CPC6128 OS ROM that I was going to fit, I would ideally like 464/6128 switchable OS as here:
http://www.cpcwiki.eu/forum/index.php?action=dlattach;topic=7010.0;attach=7604;image  Is there a 464/6128 OS file available to use?

[ZbyniuR]

DualOS with switch ?    You talk like Amiga fan.
But maybe is better with VaraDOS and XD-DOS.
I'm serious.

[dxs]

Yes it will work, however you will have to burn your 2 OS's (2*16=32ko) in the upper part of your 27c512 (64ko). The mod you gave the link for is primarily for a 27c256 - 32ko.

You can make your own 464/6128 file easily with any hex editor - simply join the 2 in a single 64ko file by putting the second at the end of the first. Let me know if you don't succeed.

[simondo]

dxs, ZbyniuR
Thanks for replies

dxs
Thanks for advice on 27C512. I have found a 27C256 but ufortunately I've no experience of burning to different parts of an EPROM.

The Amsdos/Parados file I downloaded from the link just has a single .bin file, so is this just simply burned to the 27C256 EPROM and then switch fitted?

Thanks in advance and apologies if I'm missing the obvious.

[Bryce]

You don't necessarily have to burn them to the upper or lower portion of the EPROM, the address pins just need to be set properly. However, it's simpler if you have a 27C256 than using a 27C512.

Just patch the two files together into one file (or download a pre-prepared file with AMSDOS / ParaDOS already as one file) and burn it to the EPROM.

Bryce.

[simondo]

Thanks Bryce,

I will burn that pre-prepared file to a 27C256 and do the switch mod.

[dxs]

Hi Bryce,
I looked at the DDI 1 schematic and pin 1 (A15) is at +5v, hence my remark about burning in the upper part of the eprom.

Simondo you don't need to buy 27c256 but if you already have them go ahead of course.

[simondo]

All done and working perfectly. Now have switchable Amsdos/Parados on DDI-1.

Just need to sort out 464/6128 switchable ROM.....

Thanks everyone for all your help as always.

[Bryce]

Hi Bryce,
I looked at the DDI 1 schematic and pin 1 (A15) is at +5v, hence my remark about burning in the upper part of the eprom.

Simondo you don't need to buy 27c256 but if you already have them go ahead of course.

Ah, ok. I wasn't sure what potential was on A15. I have always made it dual by default. If you're going to be adding a socket anyway, you may as well do 3 more solder joints and add a switch.

Bryce.