DRAM Coreboard repair. Advice sought

Ernest · 17-04-2022, 09:30 PM

That's Great Chesh,

As ChickenMan stated you may like to try a different boot disk image.
The 256TC was designed for an expanded graphics with 16K of PGC RAM instead of the 2K on your current Mainboard.
You will need to be careful of any of the software that was written for released specifically for the Premium or above.

Ernest

***MbeeTech*** · 18-04-2022, 12:57 AM

(17-04-2022, 08:18 PM)CheshireNoir Wrote: Wow. It boots! I'm not completely out of the woods yet. I think I might have some bad RAM somewhere. Why? If I choose "Word Processor" I get:
[Photo of Simply Write not looking as it should]

Simply Write (the word processor) needs to run on a Premium Series (or 256TC) Microbee with the extended PCG graphics banks.

The square symbols etc on the screen are actually supposed to be values that get written to the Attribute ram in the Premium / 256TC graphics
system that is not part of a standard Microbee. The Attribute ram tells the system (among other things) which bank of PCG ram to reference at that
character cell on the screen. If there is no Attribute ram in the system (in the case of a non-premium machine) the data that was meant for the
attribute ram ends up in normal screen ram, at which point you see that data instead of regular screen characters.

This explains what you are seeing on the screen.
the Square symbol is character value 0, which means that character cell is supposed to reference PCG bank 0.

An earlier version of the boot disk (made for non-premium machines) would be better to run on your system.
Great work in getting the machine going.

CheshireNoir · 25-04-2022, 11:09 AM

I just wanted to say a final big "Thanks!" to everyone who assisted me with the DRAM Microbee.
It's pretty much doing everything I want it to now. Without a Premium, I realise some software is going to not work, but I can recognise that pretty easily now I know what I'm looking at. (Thanks Ewan for the deep dive on the details there)
Currently still working on a laser cut case to top this all off. I'm up to my 6th revision, having done a fairly major rework after version 4 to fix a fundamental issue that I only noticed once everything else was working right :-D
(Version 5 was for SRAM so version 6 has been tweaked for DRAM)
Once I get the case "just right" I'll post final glamour shots in a new thread and release the DXF files so everyone can play. Think of this PDF as a "preview" :-)

.pdf

MicrobeeEasy2.0d.pdf (Size: 387.58 KB / Downloads: 278)

Ernest · 25-04-2022, 03:10 PM

That’s great Chesh,
As with all computing, there is always that, oh now I just need this one more extra?

Case progressing very well? I like how its looking.

Ernest

***MbeeTech*** · 25-04-2022, 06:17 PM

Great job with the laser cut case design Chesh.
Very impressive.

Robert · 27-04-2022, 06:57 PM

Can't open the document.

CheshireNoir · 27-04-2022, 07:03 PM

Hey Robert,
is that because you don't have access to it, or that once you download it, you can't open it in a PDF viewer?

Chesh

Ernest · 27-04-2022, 10:51 PM

(27-04-2022, 06:57 PM)Robert Wrote: Can't open the document.

Try logging off then access it.
There seem to be something strange with this site, but it only affects some of us sometimes?

Ernest

Robert · 01-05-2022, 07:19 PM

(27-04-2022, 07:03 PM)CheshireNoir Wrote: Hey Robert,
is that because you don't have access to it, or that once you download it, you can't open it in a PDF viewer?

Chesh

Don't have access - the forum gives a full-screen error message.

Anyway I accessed the site on another computer where I've never logged in, and it downloaded fine.

I was one of the first people to sign up here, and downloads / embedded pictures have never worked, and the admins can't find out why.