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Re: General Stuff(tm)
Posted: Sun Jun 12, 2022 8:49 am
by stephen_usher
Oh, VSCode is an IDE. I won't be using one of those, just a text editor and command line. I may not even bother starting X-Windows.
Re: General Stuff(tm)
Posted: Sat Jun 18, 2022 5:16 pm
by stephen_usher
I hate bit-rot.
I had decided to have one of my spare BBC Model Bs as a prize for the high score competition at Lavecon this year. So, as part of my preparations I brought the machine down to test...
Turn it on.. Boop-Beep!
Oh good.
Now let's test the floppy interface. Oh dear, reads all zeros from any drive and any media.
I've seen this before with a poor floppy cable connection but... I can trace the data right from the interface, through the LS logic and into pin 27 of the Intel floppy controller chip. (I made sure to measure on the actual pin of the chip in case it was a poor socket connection.)
Bad controller chip? Nope, swapped with one from one of my other Beebs and it has the same problem! *sigh*
Oh well, more diagnostics.
Re: General Stuff(tm)
Posted: Sun Jun 19, 2022 10:49 pm
by stephen_usher
After going around in circles and even trying to fit the FDC chip into a socket tower (which didn't work 'cos the turned pins wouldn't sit into the original socket) I got nowhere.
Then a reply on Stardot forums noted that the FDC used the NMI to signal that data was ready. The INT pin on the FDC goes through a NAND gate, with the other input held at 5V, the INT line is also connected to a jumper, S9, which is factory fitted. and holds the line at 0V, meaning that the FDC can never raise an interrupt! A quick Google confirmed that this link must be cut when the floppy disk interface is fitted!
A quick cut of the link and the machine can read disks!
Whoever fitted the floppy interface (a) didn't cut the link, and (b) never tested the machine with a floppy drive.
Given that this machine was used at work as a terminal with a ROM based terminal emulator I'm not surprised that this was never spotted.
Anyway, it all works now!
Re: General Stuff(tm)
Posted: Sun Jun 19, 2022 11:15 pm
by stephen_usher
Well, it worked for a while... but now it looks as if the SEEK signal isn't being sent to the drive so trying to load any files ends with the Error 18 (though *CAT works). I'll have to make sure that the Gotek hasn't gone wrong before opening the machine up again.
*sigh*
Re: General Stuff(tm)
Posted: Sun Jun 19, 2022 11:24 pm
by rubber_jonnie
stephen_usher wrote: ↑Sun Jun 19, 2022 10:49 pm
After going around in circles and even trying to fit the FDC chip into a socket tower (which didn't work 'cos the turned pins wouldn't sit into the original socket) I got nowhere.
Then a reply on Stardot forums noted that the FDC used the NMI to signal that data was ready. The INT pin on the FDC goes through a NAND gate, with the other input held at 5V, the INT line is also connected to a jumper, S9, which is factory fitted. and holds the line at 0V, meaning that the FDC can never raise an interrupt! A quick Google confirmed that this link must be cut when the floppy disk interface is fitted!
A quick cut of the link and the machine can read disks!
Whoever fitted the floppy interface (a) didn't cut the link, and (b) never tested the machine with a floppy drive.
Given that this machine was used at work as a terminal with a ROM based terminal emulator I'm not surprised that this was never spotted.
Anyway, it all works now!
IIRC one of my BEEBs arrived with an intel 8271 in it, though I never hooked up an FDD as I didn't have one. The link was snipped in that one I'm sure, I can go check if you want.
Re: General Stuff(tm)
Posted: Sun Jun 19, 2022 11:37 pm
by stephen_usher
Yeah, S9 needs to be snipped on Issue 4 & 7 boards
Re: General Stuff(tm)
Posted: Mon Jun 20, 2022 10:01 pm
by stephen_usher
OK, I seem to have got the machine stable, though the DFS 0.9 ROM does cause issues with Elite, with 12 second waits before it accesses the disk.
I tried using an EEPROM with DNFS 1.2, as I have in my other Beebs, but the machine doesn't like it. Oh well.
Re: General Stuff(tm)
Posted: Tue Jun 21, 2022 11:55 am
by stephen_usher
Hmm... Looks like I may be picking up a Faclon030 in a little over 3 weeks time.
Re: General Stuff(tm)
Posted: Tue Jun 21, 2022 12:06 pm
by alexh
stephen_usher wrote: ↑Tue Jun 21, 2022 11:55 am
Hmm... Looks like I may be picking up a Faclon030 in a little over 3 weeks time.
Nice. Just in time for the re-release of the CT63?
Re: General Stuff(tm)
Posted: Tue Jun 21, 2022 12:13 pm
by stephen_usher
I'll keep it as stock as possible I think.
It'll need the clock chip looking at. I'll probably just grind the top off the case and solder a CR2032 holder to it. It'll probably also need the clock patch.