QL startup issue

[voutsasva]

Hi everyone,
Ι need desperately your precious help. The issue is that on the boot up it displays red, green vertical bars and also white horizontal lines.
QL is connected to tv and the motherboard is issue 6.
What can I do to fix my favourite computer?




Thanks in advance,

Vassilis

[tofro]

Looks like a memory problem.

Either one of the RAM chips failed or one of the multiplexers (74LS257). If I had to guess, I'd guess the latter

what is your measuring equipment like? How's your soldering skills?

Tobias

[voutsasva]

Hi Tobias,
thanks for your reply. I will try to replace the two 74LS257.I hope not to need replacement the RAM chips, because it will be "painful" to find the faulty.
I have a multimeter, so If you have something in your mind to check please enlighten me.

Thanks,
Vassilis

[Martin_Head]

Hi Tobias,
thanks for your reply. I will try to replace the two 74LS257.I hope not to need replacement the RAM chips, because it will be "painful" to find the faulty.
I have a multimeter, so If you have something in your mind to check please enlighten me.

Thanks,
Vassilis

If it's a RAM chip, then a Minerva ROM should be able to tell you which chip is faulty during startup

Martin Head

[stevepoole]

Hi Folks,
I have a JS SGC, SuperHermes, romdisk, with twin ED floppydisk.
When I do a DIR there is no problem, but as soon as I try to load a superbasic program the QL locks up.
HD Programs load and run OK on QPC2...
This means many programs written on ED disks are no longer accessible to me.
What could have gone wrong?
Any suggestions?
Regards,
Steve Poole.

[Martin_Head]

Hi Folks,
I have a JS SGC, SuperHermes, romdisk, with twin ED floppydisk.
When I do a DIR there is no problem, but as soon as I try to load a superbasic program the QL locks up.
HD Programs load and run OK on QPC2...
This means many programs written on ED disks are no longer accessible to me.
What could have gone wrong?
Any suggestions?
Regards,
Steve Poole.

A few more details might help.

Is it just SuperBASIC programs that don't work? or executables as well?
Can you load programs from the romdisk OK?
What about Microdrives (if you have any cartridges)

Can you try another floppy disk drive, it doesn't have to be ED

Do you have any BOOT program (in the romdisk) that might be playing about with things like the FLP_STEP command, or other FLP_ commands which might confuse the floppy disk drives. It might be worth checking out the SGC manual and try setting all the FLP_ commands manually before trying to read a floppy disk.

What happens if you try to format a floppy disk?

Do the floppy disk drives just need cleaning with a cleaning disk?

[tofro]

I am not sure if I get all of the question right. Are you saying "My setup works with HD disks, but not ED disks" (Because you mention QPC)?

Can you check what happens if you are not LOADing the S*Basic program, but rather VIEWing it? You might then be able to locate the corrupted part. Is there a certain point where it reproducibly stops?

The fact that LOADing seems to be working flawlessly on HD disks seems weird, like some buffer memory bad that is not used when HD floppies are involved.

Tobias

[Martin_Head]

I am not sure if I get all of the question right. Are you saying "My setup works with HD disks, but not ED disks" (Because you mention QPC)?

Can you check what happens if you are not LOADing the S*Basic program, but rather VIEWing it? You might then be able to locate the corrupted part. Is there a certain point where it reproducibly stops?

The fact that LOADing seems to be working flawlessly on HD disks seems weird, like some buffer memory bad that is not used when HD floppies are involved.

Tobias

I think something went wrong with the above message... The first line was not displayed.

[Martin_Head]

An then it suddenly appeared...

[stevepoole]

Hi Folks,
Here is the beginning of answers to the various questions posed :
I try to load a program on HD diskette on my SGC ED floppy drive. Result, the loaded program is riddled with MIStakes, or the QL locks up.
I load the same program on the same diskette on a QPC2 PC with floppy drive and all is OK.
Normally the ED drives used to read HD disks OK.
Result : I can access my programs on HD diskettes on my QPC2 PC.
I cannot access programs on HD nor ED diskettes on my SGC QL.
The SGC QL reads programs OK off ROM1_ where most commercial programs are located.
Most of my own superbasic programs are on diskettes, many on ED...
I was trying to sort through my routines for the QL preservation scheme, which would have needed some tidying up!
Hope this helps...
Steve Poole.