NC100 and 2MB memory cards - SOLVED!

[Munchausen]

Hi all,
just got myself an NC100, and I need an SRAM card. I'm wondering if anyone knows what happens if you use a 2MB card in it? Do you just get access to 1MB only? As I understand, if I put a switch on the relevant address line I could actually have effectively two switchable 1MB cards? The 2MB cards are available for cheaper than 1MB at the moment, it's mad!

[MaV]

I found a German thread where this question has been answered:
http://forum.z80.de/showtopic.php?threadid=196

Two things are mentioned that seem to be important:
- The card needs to be PCMCIA type I where the connector is 3,3 mm thick; newer type II cards are 5 mm with slightly thinner outer edges.

- In Post 14, there's confirmation that a 2MB Transcend card is accepted but the NC100 only uses 1MB.

[TFM]

Hi all,
just got myself an NC100, and I need an SRAM card. I'm wondering if anyone knows what happens if you use a 2MB card in it? Do you just get access to 1MB only? As I understand, if I put a switch on the relevant address line I could actually have effectively two switchable 1MB cards? The 2MB cards are available for cheaper than 1MB at the moment, it's mad!

From experience I don't recommend that. 1 MB is fine, 128 KB cards work even better (fewer data loss), but 2 MB does not work.

[Munchausen]

I bought a 2MB card and indeed it is erratic - the highest address pin is floating, so sometimes you see one half of the card and sometimes the other. This seems to confuse the hell out of the NC100 OS!

I've managed to fix the problem though. My first thought was just to solder A20 to ground, which would force the card to only ever use 1MB, but I decided instead to add a switch that allows me to switch A20 between 5V and GND, so I can use both halves of the card, you then effectively have two 1MB cards that you can switch between (a bit like a side switch with a 3.5" drive on a CPC).

Below are some pictures of the mod. I didn't want to cut a hole in the case, so instead I have just removed the bezel around the PC card slot, so this NC100 can easily be returned to stock.

[pelrun]

Oh, duh! That explains the problems I had with my card in my NC100 years ago. Nice to have a mystery solved!

[Ygdrazil]

Hi Munchausen

Really nice... As I need doing stuff exactly with 2MB ramcards on the NC for an upcomming project.. Can I make an article about it in the WIKI using your picture?


Regards,
/Ygdrazil

I bought a 2MB card and indeed it is erratic - the highest address pin is floating, so sometimes you see one half of the card and sometimes the other. This seems to confuse the hell out of the NC100 OS!

I've managed to fix the problem though. My first thought was just to solder A20 to ground, which would force the card to only ever use 1MB, but I decided instead to add a switch that allows me to switch A20 between 5V and GND, so I can use both halves of the card.

Below are some pictures of the mod. I didn't want to cut a hole in the case, so instead I have just removed the bezel around the PC card slot, so this NC100 can easily be returned to stock.

[Munchausen]

Hi Munchausen

Really nice... As I need doing stuff exactly with 2MB ramcards on the NC for an upcomming project.. Can I make an article about it in the WIKI using your picture?


Regards,
/Ygdrazil

Thanks! I'm happy if you'd make a wiki page. FYI I used a 10K resistor on the switch, it's just a hold up to 5V.

[Munchausen]

Another note about pins. On the picture showing the cables soldered to the PC card socket:

The bottom pin (lowest down) is ground.
The next one is A20, it is the 8th pin counting from the bottom pin (the ground pin).
The next one up is 5V, the 9th pin from the bottom.

Also, I have higher resolution pictures I can attach, I left them out because when you click on them in here they become absolutely massive.