stardot.org.uk

i tried to launch zxspec, following instruction displayed with !boot on ssd spectrom, but i get "bad command" error with MOS 3.2 in my Master (@RobC: i take off for the moment one of my 2 videonula from other BBC... but i hope to get my 3rd vnula soon! ;) ). *zxinit let screen a bit darker, and *zxs...

Reallly an interesting project Dave!
i am interested in one or two pcbs too... are there some left?
You should put a countdown counter for them!

Thanks Kazzle, your hints are very helpful! I will use the weekend for resocketing and getting pics of board when "nude". A little OT, about instruments, I bought from aliexpress the scope (LA1010 usb) for 25£ shipped, after some years of a Diy kit that worked in a very random way. And, from aliexpr...

Kazzle, now I realized that there was a misunderstanding: S21E goes to IC18 (the sl138), and I referred test and probing to it, while you was talking about ic16! Really sorry for it, I will have to sleep a bit more in the night instead of playing with old computers.. 😁 Anyway I'll follow your guidel...

in my case it seems i have two inputs... it's not the wiring the fault Ah. Ok. Is it possible that S21W is actually connected to more than one IC on the ROM / RAM board, or to more than one pin on IC1? That's what i thought too and... yes! s23w is connected to IC19 pin 8 too (74ls20)... an output! ...

Thank you Kenlowe for the info, but in my case it seems i have two inputs... it's not the wiring the fault, but i'd like to understand the board to perform further test.

But.. S21 West is connected to Pin 1 of IC1 (74ls00), that is an input to the first nand gate of ICs... and pin 3 in fact is not flat and waves... So, is W the input and E the output, or viceversa? i am confused... That does sound like it's the wrong way round! On the beeb motherboard S21 SE is nor...

Does the board need it's own 5v supply? Where does it pick that up from? it keep power from vcc2 psu spades and return it to board with its wires... But.. S21 West is connected to Pin 1 of IC1 (74ls00), that is an input to the first nand gate of ICs... and pin 3 in fact is not flat and waves... So,...

So the Beeb is sending plenty of (active low) S21 requests to the board, but the board isn't sending any back. That's in keeping with the behaviour you've described so far. (BTW, is S21E connected to IC16 pin 5 or pin 6? Your last two posts mention both pins.) Now that you've got a scope to hand, i...

Anyway, i get this wave at boot for S21 pins from expansion board:
West go high and stay there...

Briliant analysis!
i confirm West S21 is connected to IC1 pin 1, and Est S21 to pin 5 IC18 (active low inputs? i expected an output...)
i'll made some test... if only i'll find the probe for my usb scope... it's an hour i am looking for them!

Great work Mark, even better than schematics! I will start this evening from suspect ICs, testing continuity and looking for correct response.. Some works to do!

@Paul: a test without ram was one of first things I tried.. No difference
@kazzle & Mark: thanks for all info! I had a little idea of selection logic, made myself while doing the "diy sw ram for under a fiver" in other BBC... Now I have more starting point for testing.

Thank you Kazzle, you explained very well the rom selection logic, and confirmed most of the ideas I made myself. I have already checked E and W expansion board for continuity, and they are ok from connectors to the two ICs on the Watford card. So, I am afraid of one or more 74xx failure, but they a...

Thank you Mark, control signal and control circuit is the direction I intend investigate, since the only case I get basic rom working is when fitted in mb slot and link S21 closed with classic bridge (I.e. not connected to expansion board via dedicated wires). All other combinations port to "languag...

Thank you, but i am sure it's not a metter of slots or eprom, they work fine in mb slots and in mb other micros, and i tried a lot of combination, included no rom at all on expansion board, getting always the "language? " prompt...

Just got the same board in a BBC last weekend. The user guide is here: http://chrisacorns.computinghistory.org.uk/docs/Watford/WE_RAMROMBoard.pdf Thank you Paul, but it's the manual I quoted in my first post, and it only relate "language?" Error to S21 link. I had the 2 fixed voltage I reported in ...

found : https://stardot.org.uk/forums/viewtopic.php?f=3&t=8755&p=96318&hilit=watford+rom+ram+disc#p96318 your board should be like this, ignore the extra ram top right : Really a monster your WE! why didn't you fit the battery? you already put the read only switch i se... if i'll get mine working, ...

Thanks for the hints CMcDougall, but it's not the slot the problem.. i made several tests, but even without any roms in the boards i get only the "language?" error...

That's the WE ram/rom 128k board:

I bought in the bay a second BBC Micro, reasonable price, with an interesting big black suitcase with Micro siluette for carrying it (yes, a portable beeb diy!) :lol: I power on it and.... continuos beep! Ok, let's look inside. Open the case and... a varta 3.6 battery rolls away on the table, and a ...

Hi Philb, i am interested in one of the B32's, is there one still available?

Good news! My complimenta to you and ians!

i used simple "male pin strip" bought for pennies in the bay, cutted and soldered in 2 rows... if you have to cut.. what's about doing same thing with female ones?

Great works! And your desk is in great order compared to my kitchen! (My Amiga 600 still doesn't boot.. I must move soldering station elsewhere ...)

After hours spent in trying to repair the A5000 i bought "not working" in the bay, i must admit it's death.

Anyone has in a A5000's motherboard to sell at a reasonable price?

And a useful proof about A5000 is working may be if it "beep" when booting, and if keyboard leds works.
And, of course, opening the A5000 and looking around battery area. As robc said, I am afraid the A5000 is damaged, and it is not a video question... I hope for you I am wrong

Thanks, sorry I'm confused what do I use the db9 serial cable for, the mouse? I thought I plugged the mouse into the DIN socket at the rear of the keyboard? No, you are right, the standard mouse port is a mini Din-9. I was confused by your writing about the DB9, and i thought you was planning a DB9...

I usually use db9 serial cable, cheap and with less wires than a scart.
Give a tray to your floppy and ide ports if working, you can check them from command line, without mouse.
If you had damage to keyboard tracks, more probably you lost some connection on that ports, that are nearest to battery

So, in a couple of months they will arrive!