Memory mapping and PCMCIA

[Hodgkinson]

Hi all,
Im wondering wether anyone could confirm the belif that the PCMCIA port requires 4MB of addressing space to function, and that if the RAM (In my case on a A1200 expansion slot connector) exeeds 4MB in size, without a MMU the system cannot correctly address both the extra RAM and the PCMCIA slot at the same time, resulting in one (Or both) not working correctly due to confilcts?
I've been reading the A1200 manuals and I see no mention of conficts between >4MB RAM installed and the PCMCIA port.

Im hoping to be able to have 8MB of fast ram on a expansion board (No MMU) and still be able to use my 3C589 network card as per normal.

Thanks,
Hodgkinson.

[bubba]

You are correct.  You can only use a max of 4MB RAM if you are using the PCMCIA port.

-bubba

[alexh]

It really depends on the make / model of RAM card as to whether you can use more than 4Mbytes without screwing up the PCMCIA port.

The PCMCIA is mapped to the upper 4Mbytes of the traditional 8Mbyte FAST-RAM area.

If you have 8Mbytes of contiguous RAM in standard 24-bit fast RAM area then you WILL overlap the PCMCIA address and get problems.

Some cards get around this by adding the other 4Mbytes of RAM to other strange address locations. They sometimes need an extra driver to activate the other 4Mbytes.

[Hodgkinson]

So keeping the 4MB expansion in the A1200 sounds like a good idea, as I can still use the network card whenever I feel like it (Unless a card with a MMU comes my way  :-))

Fortunatly, I can boost the RAM to 5MB with a PCMCIA SRAM card I have and configure it as system RAM...nothings ever impossible with Amiga :-):-)

Thanks,
Hodgkinson.

BTW, Has anyone out there got a greater than 1MB but less than or equal to 4MB Amiga compatible card out there that they might sell?

[rkauer]

Or simply check ebay every week for Amiga acelerator boards. Most of them have a way or another to bypass the PCMCIA RAM adress issue.

I have 128 Mb 60ns FastPage SIMM(yessssssss!:evilgrin:) on mine MX 1230 XA (Microbotics).

[alexh]

rkauer wrote:
Most of them have a way or another to bypass the PCMCIA RAM adress issue.

I have 128 Mb 60ns FastPage SIMM(yessssssss!:evilgrin:) on mine MX 1230 XA (Microbotics).

That is an accelerator. Almost all accelerators can be PCMCIA friendly as they can put FAST RAM in 32-bit address space.

The conversation is about RAM cards.

[Zac67]

An MMU will not help you here since the conflict already happens in physical address space and there's no way to fix this through some logical remapping.

As has been said before, an accelerator card with memory will solve this problem though.

[zipper]

Except with those crippled cheap accelerators with 24bit addressing.

[Hodgkinson]

Thanks for the replies.
Next problem...How to change the priority of each chunk of RAM?

The problem is the system has allocated the 4MB of FAST RAM on the RAM board as the highest priority. That’s great for normal use, but this means that my largest block of RAM gets taken for running PCx and the OS (I’m trying to set up PCx on the system - And the RAM's far from enough), rather than for providing the base and extended memory for the emulation.
As the memory for base and extended memory can only be taken from one user definable location, is there any way to make the priority on the Chip RAM and PCMCIA card RAM such that they are used first, leaving plenty of space on the RAM board for the emulation to use?
If theres a way to do this from CLI or Shell that would be best as then it might be possible to write a script to set up the RAM priorities (And check that the PCMCIA RAM card is present) before loading up PCx - And set the RAM back to normal once PCx has been closed.

Hope this makes sense.

Thanks,
Hodgkinson.

[alexh]

Zipper wrote:
Except with those crippled cheap accelerators with 24bit addressing.

Note that I said "almost all".

Hodgkinson wrote:
I’m trying to set up PCx on the system

Why would you EVER want to do that? FFS use a PC! You've lost all my sympathy :-)

Long since gone are the bad old days when all we had was an Amiga.

[Hodgkinson]

:-)

I've got so many PC's around the place I can't even be bothered to list them all - But I still want to use the A1200 with PCx since im a radio "Ham" with limited bench space who wants to put his slightly-expanded A1200 to good use (Even though I already use it for AmiCom etc…). I've got stacks of old DOS radio applications that I would sooooo love to see running on my A1200 - Especially given the fact that such applications can be picked up on DD disks from radio rallies at £1 for 50 disks...

Any suggestions on the RAM-Priority problem?

Hodgkinson.

[alexh]

http://aminet.net/search?query=priority+memory

[Hodgkinson]

Now they could be useful  :-D  Thanks.

Any suggestions (From past experience) on which one to use (Spoilt for choice as usual)? I require one that can be easily called from a script and (Preferably) doesn't permanently affect the RAM priorities (E.g. Rebooting restores the system defaults). Unfortunately they all appear very similar to one another and the readme’s don’t give many clues.

Also, how might I go about creating a script to first check whether the 1MB (Formatted as RAM) PCMCIA card is present (If it isn't then display a warning, wait, then quit the script), set the memory priorities, and run PCx. Once PCx is closed, set the memory back to the original setting and exit the script?
The bit I’m not sure about is checking for the presence of the SRAM card as system RAM, and whether the stack size of the script is independent or not to the running of PCx.

Thanks for all your help,
Hodgkinson.

[alexh]

http://en.wikipedia.org/wiki/ARexx