Risc PC - boot issues?
Paul Turner (6061) 10 posts |
I am working on a Risc PC with RISCOS 4.02 for a friend (I owned one about 20 years ago!) and seem to have a problem with the boot sequence. Only low resolution (or limited colour) desktop modes are available despite having 2MB VRAM and moving windows around is very sluggish. Scrolling is very slow and dragging the scroll bar moves a dotted outline rather than the bar itself. It’s as if something has not been initialised properly during the boot sequence. Any hints on where to start looking? Many thanks, Paul. |
Chris Evans (457) 1614 posts |
Have tried doing a power on delete? The first character will be a pipe character “|” replace it with “L” When you click on the hard drive for the first time do you get a ’No Boot application has been run…" error? |
Paul Turner (6061) 10 posts |
Thanks for the quick response Chris. Power on delete has helped a bit – the scrollbar does move without the “outline” effect but it is still quite slow and jerky and screen modes are still restricted in colours/resolution. Does the machine need to be told it has VRAM? If so, where? 20 years is a long time and I can’t remember. I had RISC OS 3.70 back in the day and it seems 4.02 is a bit different. I don’t get the “No boot application has been run …” message, BTW. Thanks again, Paul. |
Chris Evans (457) 1614 posts |
Are you able to change screen resolution? VRAM is auto sensed. On booting the pre desktop text gives the amount of RAM found, it includes your VRAM, what does it say? If VRAM faulty you need to edit “To reset that look in:ADFS::HardDrive.$.!Boot.Choices.Boot.PreDesk.Configure.noVRAM” |
Paul Turner (6061) 10 posts |
Yes, I can change screen resolution, but with a limited number of colours. Best I can do with 256 colours is 800 × 600 – if I select 32K colours the resolution drops. I doubt the VRAM is actually faulty as it was working fine last week. I can’t read the pre-desktop text as it disappears off the screen too fast. I still think it’s some kind of boot sequence issue; I have an almost identical machine and I might try copying some of the boot files from that – if I can work out which ones I need and can get the necessary files to fit on floppy disks! Thanks, Paul. |
Will Ling (519) 98 posts |
Perhaps the boot sequence is starting, but something early on causes an error. To catch the text on screen, hold Shift and Ctrl togeather after the first lines appear (not too soon or boot will skip altogeather, might need a few goes to get the timing right), then briefly release and repress shift and you should be able to get one line to appear at a time. You might be able to catch any error message that way. Also, worth double checking the monitor is configured correctly: double click !Boot to open Configure, then check the Screen section. |
Steve Pampling (1551) 7925 posts |
The Rick Murray utility Harinezumi will help by logging the boot sequence and logging the successes and failures in the boot sequence. |
Paul Turner (6061) 10 posts |
Thanks Will and Steve. I will have another go tomorrow. |
David Feugey (2125) 2687 posts |
Check the total amount of RAM with a click on the Acorn logo. You’ll now if the VRAM is recognized or not. |
Paul Turner (6061) 10 posts |
“Check the total amount of RAM with a click on the Acorn logo. You’ll now if the VRAM is recognized or not.” Where does it show VRAM? The machine has 72MB of RAM and shows all the usual memory allocations (red and green bars) but no mention of VRAM. I don’t remember seeing VRAM listed on there when I owned a Risc PC. EDIT: The machine appears to have its original CMOS backup battery (now reading about 1.3 volts) so obviously that needs sorting. However, I still think there are boot sequence issues. |
Rob Andrews (112) 160 posts |
This must be a kintic strongarm machine with 64Mb on the card with maybe 2 × 4mb simms or 1 × 8mb simm in the socket so the vram is not working because a 1mb vram would show an odd number of ram ie 73mb a 2Mb vram would show 74MB |
Paul Turner (6061) 10 posts |
It seems to have a 64MB SIMM and an 8MB SIMM and reports 72MB at startup and on the task display. I’ve just realised that the CMOS battery is only a single cell so 1.3 volts is fine, but there are early signs of leakage so I think it needs replacing anyway. |
Rob Andrews (112) 160 posts |
so no vram working try taking the vram out of the slot and reinserting to clean the contacts sometimes works the cmos will have no effect on the ram total as i said before odd number for 1 MB even for 2MB so 73 or 74MB with working vram the risc Pc may not be reliable with a 64Mb simm as i remember 2 32Mb simms ok but timing problems with 64Mb simm |
John Williams (567) 768 posts |
There’s a DIY option here which may be of interest. CJE also do a kit, I believe. |
Chris Evans (457) 1614 posts |
As Rob says, the VRAM is not being detected. If it could see VRAM you wouldn’t be limited to 256 colours in 800 × 600. I have seen damaged VRAM sockets mean the SIMM is not detected. |
Will Ling (519) 98 posts |
It is possible for a leaky battery to wipe out the vram. I had one risc pc with quite severe leakage that had welded the vram in. Check the module and socket for blue/green residue or a general dulling. Hopefully there is nothing that bad, but gentle cleaning and reseating the vram may fix it. Also a leaky battery wants replacing sooner rather than later. |
Paul Turner (6061) 10 posts |
It’s certainly beginning to look like a VRAM issue. Cleaning and reseating has partially brought it back to life, with 74MB RAM now reported at boot-up but considerable corruption of the display. There is no obvious corrosion or discolouration on the top side of the main board but the VRAM has tinned connections rather than gold plated and I guess after 25 years the tin could be suffering a bit. Thanks for your help. Paul. |
Chris Evans (457) 1614 posts |
Not sure if it relevant, Simtec VRAM used a thicker PCB than Acorn and were very very hard to fit! |
Steffen Huber (91) 1945 posts |
Try to reseat it multiple times, it looks like the socket might be a bit dirty. Tin connections are a good thing here since the socket is also a tin connection, and gold-vs-tin is chemically a bad thing (or at least that was what I was told years ago in some audio forum). |
Wouter Rademaker (458) 197 posts |
Try to clean the contacts with a pencil eraser, that will help sometimes. |
David Feugey (2125) 2687 posts |
Or a toothbrush with some alcohol on it (for the VRAM socket, not your mouth :) ) |