A500 MTEC 68030/14Mhz

[bebek]

Hi,
I have bought a turbo card for A500: AMIGAPOWER Mtec 68030/14Mhz 1/4Mb. 030 are good for overclocking. Does anybody know if I can overclock this one without much fuss ? How to expand memory on it, what ic to use? Any help is appreciated.

[coze]

this doesn't look good. The 68030 is a 20 MHz part, so it's actually downclocked. They probably did this for good reason. 14 MHz is probably taken from the motherboard. I'm not sure if it's good/advisable to overlock this (you'll have to cut the 14 MHz coming from the mobo, and get a faster signal from your own crystal).

Same thing for the RAM. It seems your unit is a 4 mb board. It's not an autoconfig board, which is good if you want to piggy back your own ram on it, but how you're going to interface it with the ram controller is totally another matter (In other words, I have no idea)

http://amiga.resource.cx/exp/mtec530

[rkauer]

Piggybacking memory chips is not an issue if you want 8Mb of FAST RAM, but you need some electronic knowledge to perform this.

First check if you can grab 8 more memory chips totally equivalent with those already installed, them ask for more help.

[Zetr0]

@bebek

Over clocking -

insofar as over-clocking the 030, you could easily source a clock for the CPU from the FPU clock.

you will need to cut the track that carries the clock from the 68k socket (others have mentioned this)

However I believe you will encounter a lot of stability issues if you move this board from sycronus with the motherboard to asyncronous. I believe the problem you will most likely encounter (other than latching times and slow IC's) is XOR'ing back to the motherboard on EClock (0.7mhz).

If memory serves you could source this from CDAC, but please double check the specs on the A500/A2000

I think if the CPLD logic is willing, with a little jiggery poker its possible to get this upto 21mhz, any more than that I think the card will bottom out, although you could source 28mhz from the Agnus if you wanted to try.


Upgrading the Ram

This might be a little tricky, HOWEVER, this particualr card requires that you ADDMEM using software, this is to our advantage as this means the CPLD's only address the ram in a specific way -

looking at board I would suspect it is setup as 32bit access for the 030 (this would improve speed with the 030 burst mode)

Here is the data on the memory chips -

The memory chips are TC514400ASJ-80 -

Toshiba Semiconductor - 1MX4 (1,048,576 x 4 BIT DYNAMIC RAM) *click for pdf datasheet*

These chips are quite common, normally found on 4/8 and 16mb 72pin Sims and 4mb 30pin simms

Now we could use a piggy-back method but would you would need to inspect the memory map of the card, how does it arrange the ram, at the moment we could only guess at 1024k * 32bit (remember its a guess)

from this the quickest method would be to increase the addressing space to 2048k * 32bit, (*i.e. biggy backing*) to access this upper 4MB of ram you would need to generate the upper address signal (probalby a RAS signal) based on the the CPU request.

tricky, and a lot of research, but not impossible, I would estimate a good 4 months work.

It might be easier to see if the code is readable on the CPLD's and if it could be *modifed* to generate another RAS signal, (this if course would mean some 30awg moments =D)

[bebek]

@Zetr0

Wow. Thanks for this . Looks like I will try memory first if it is 1MB (it is still in the post) and later CPU. I have started to many things to spare 4 months work . Thanks again for the info.

[rkauer]

As a side note: normally accelerator designer manage to keep the disabled 68000 supplying the E_clock for motherboard timings.

Nothing to worry about this, so.

[bebek]

Originally Posted by rkauer

As a side note: normally accelerator designer manage to keep the disabled 68000 supplying the E_clock for motherboard timings.

Nothing to worry about this, so.

You gave me hope .

[bebek]

I connected 20MHz crystal to CPU and it does not work . Yellow screen and restart. Th original 14MHZ is done on one gate of F86 . One input goes to 5V and second to one Altera and one GAL. The 14 MHz is going only to CPU. Any ideas what should I look for ? What changes ?

[Zetr0]

instead of 20mhz try 21 (ie. a derivative of 7) that might just work, but its most-likely all tried to the timing of the GALs =(

whats the memory onboard?

[bebek]

Originally Posted by Zetr0

instead of 20mhz try 21 (ie. a derivative of 7) that might just work, but its most-likely all tried to the timing of the GALs =(

whats the memory onboard?

I will try 28MHz from Amiga, that is the only one I have got. i do not know what mem it have as I did not use addmem yet. BTW I have no idea what addresses I should give to addmem. Would GAL's be so slow ? Maybe I will try 7MHz and see if this works ...

Ok - tested 28MHZ - no luck, grey screen - dead, tried 12MHz - 3 grey screens like normal boot and locks. So it looks like it is synchro problem.