The Sinclair QL Forum

The aurora I have with Minerva 1.92 and SGC attached always fails ram test first time with this error.
The thing is that’s the first 4 bytes of Minerva rom. So it shouldn’t be testing it.

Any ideas?

Is that the redirected ROM address?

The location it is having an issue with is 0x0400000, which is the address immediately after the 4MB SGC RAM area - I believe this is where SGC maps the original ROM to (in your case Minerva).

I wonder if you need to tell the boot loader not to test after 4MB limit? - there was a way to do that in the I2C battery backed RAM that's on your Minerva.

I vaguely remember reading an article about how to reset that RAM so that it will default to checking for duplicated ROM images in the address map - which it should do...

Pr0f wrote:Is that the redirected ROM address?

The location it is having an issue with is 0x0400000, which is the address immediately after the 4MB SGC RAM area - I believe this is where SGC maps the original ROM to (in your case Minerva).

I wonder if you need to tell the boot loader not to test after 4MB limit? - there was a way to do that in the I2C battery backed RAM that's on your Minerva.

Yes according to Markus excellent doc that’s the remapped rom!

I suspect that with the age of that Minerva board - the battery is long dead - may just need to be replaced and the RAM left to clear itself.

Pr0f wrote:Is that the redirected ROM address?

The location it is having an issue with is 0x0400000, which is the address immediately after the 4MB SGC RAM area - I believe this is where SGC maps the original ROM to (in your case Minerva).

I wonder if you need to tell the boot loader not to test after 4MB limit? - there was a way to do that in the I2C battery backed RAM that's on your Minerva.

So when that ram is invalid it tests the whole 16M address space?

Stores the first address it fails in i2c?

Reads this on subsequent boots?

As that would 100% explain behaviour I am seeing with dead battery!

This is from the Minerva manual - page 53:

Fitting and Getting Started

Fitting is very similar to the original Minerva - see the instructions for this. The rechargeable
battery can be placed anywhere convenient in the QL; we have allowed
enough wire to put it in the spare corner of the case between the 64-way expansion connector
and the back wall.

All Minerva RTCs are tested and pre-configured with the correct time. Mishaps do occur,
however, and it is possible that the contents of the RAM will have become sufficiently
scrambled to prevent the QL from starting. To get the system going, press and
release the QL’s reset button TWICE within one second or so: you should then see the
usual tweed pattern.

The clock will always be copied into the QL’s 32-bit seconds counter whenever the QL
is re-started. You can prevent the other configuration information (see below) from being
used by pressing the left-arrow key after reset but before the F1/F2 etc. message appears
- useful if you want to check what ROMs you have plugged in without changing
the configuration, for instance.

hopefully that will get you going - but you really do want to get that battery swapped out It's probably just a 3.6V NiCd with tags - and then shrink wrapped to stop it shorting to anything.

Pr0f wrote:hopefully that will get you going - but you really do want to get that battery swapped out It's probably just a 3.6V NiCd with tags - and then shrink wrapped to stop it shorting to anything.

That I found
I assume a cr2032 would be suitable replacement!

the CR2032 is a non rechargeable lithium cell - and the Minerva board probably has a charge circuit on board for that battery - in fact I think it may even be built into the RTC chip on the board - so you should replace it with a rechargeable.

However, you can wire a diode in series with the battery - with the stripe on the diode being furthers away from the battery positive - and this will prevent current entering the battery - then you can use a Lithium cell.



Positive to Minerva (red lead) ----|<---+||- ----O volts (black lead)