A5000 Only Showing 1MB of RAM

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
User avatar
vectorlight
Posts: 189
Joined: Sun Apr 10, 2016 12:23 pm
Location: UK
Contact:

A5000 Only Showing 1MB of RAM

Postby vectorlight » Fri Mar 02, 2018 4:04 am

Hi All,

I'm attempting to fix one of my A5000's that has been sat in the loft for a while. It suffered from the usual battery leak but I've cleaned it up and repaired some of the tracks around the RTC chip area and the computer boots to the desktop okay.

The only problem is it reports only 1MB of RAM. I have the jumper on LK24 between 1 & 2 which I think is wrong? Connecting it between 2 & 3 (which I think is correct for 2MB?) causes a RAM control line fault to be flashed via the floppy drive at boot up.

So I suspect one of the RAM chips is busted. Any tips on how to work out which chip is faulty? Or if I've got the right jumper set on LK24? LK23 has no jumper on it which again I think is correct for 2MB

Thanks!

Dan
3D Printing and Acorn A3010 Owner!

RobC
Posts: 2141
Joined: Sat Sep 01, 2007 9:41 pm
Contact:

Re: A5000 Only Showing 1MB of RAM

Postby RobC » Fri Mar 02, 2018 7:17 am

Here's the info on the memory links taken from the circuit diagram:
A5000_Memory_Links.jpg


For 2MB on-board and no memory expansion, connecting 2-3 on LK24 should be correct so would seem to indicate a fault. I'd buzz out the tracks in the memory circuit before looking to change RAMs. The circuit diagram can be found in the TRM drawings.

User avatar
vectorlight
Posts: 189
Joined: Sun Apr 10, 2016 12:23 pm
Location: UK
Contact:

Re: A5000 Only Showing 1MB of RAM

Postby vectorlight » Mon Mar 05, 2018 9:10 am

Thanks Rob, I'll have a look at that tonight :D
3D Printing and Acorn A3010 Owner!