Search found 339 matches

by Colday
Sun Sep 20, 2020 8:51 pm
Forum: 8-bit acorn hardware
Topic: Beeb keyboard types
Replies: 6
Views: 160

Re: Beeb keyboard types

There is some interesting info here: https://deskthority.net/wiki/Acorn_BBC_Microcomputer This is interesting as in my experience (and I can provide photographic evidence) that wiki page is inaccurate. I have 7x beebs here and the key switches are distinct. I have fully angled futaba keyboards, str...
by Colday
Sun Sep 20, 2020 5:51 pm
Forum: 8-bit acorn hardware
Topic: Beeb keyboard types
Replies: 6
Views: 160

Re: Beeb keyboard types

Aas far as I am aware there are 4 types of keyswitch, therefore 4 versions of keyboard? There are the Futaba Black switches (2x types, straight and angled), there are the white switches, and the PED (Phillips design). These are the ones I have found so far anyway. As for quality... I've not really n...
by Colday
Fri Sep 18, 2020 7:48 pm
Forum: 8-bit acorn hardware
Topic: I need to learn
Replies: 7
Views: 296

Re: I need to learn

I had this back in the day. From memory, it doesn't go into every aspect of 6502 assembly language (possibly ignoring some addressing modes) but it was a good introduction and can be downloaded from here . If you can get hold of it, "Assembly Programming made easy for the BBC Micro" by Ian Murray w...
by Colday
Fri Sep 18, 2020 5:47 pm
Forum: 8-bit acorn hardware
Topic: I need to learn
Replies: 7
Views: 296

I need to learn

Good evening all. Ok, I've been reading (a dangerous exercise) and I find that I need to learn... stuff. I want to understand this... https://tobylobster.github.io/mos/index.html And I do understand lots of it, but it's the jargon that gets me (as it does with most specific directly oriented subject...
by Colday
Fri Sep 18, 2020 4:02 pm
Forum: 8-bit acorn hardware
Topic: Master startup beep question
Replies: 6
Views: 153

Re: Master startup beep question

The first beep is the result of the registers in the sound chip being in random states when it's turned on, hence it'll never be quite the same. Second is issued by the operating system and will always be the same :) d. Is that the same for the Model B? As I often get a choral note Also, does the R...
by Colday
Sun Sep 13, 2020 10:32 am
Forum: 8-bit acorn hardware
Topic: Keyboard switches
Replies: 1
Views: 94

Re: Keyboard switches

So, I've tested all the switches and it seems 10 have failed.

This is what I'm dealing with...
IMG_4877.jpg
by Colday
Sun Sep 13, 2020 9:04 am
Forum: 8-bit acorn hardware
Topic: Keyboard switches
Replies: 1
Views: 94

Keyboard switches

Morning all. So, now the dishwasher beeb is working, I am turning my attention to the keyboard from it. You can see from the huge rust splotch where the water was dripping into the machine and obviously over the years several of the key switches have rotted away internally (and the solder had also c...
by Colday
Sat Sep 12, 2020 2:58 pm
Forum: 8-bit acorn hardware
Topic: Silent, nothing visible
Replies: 130
Views: 2763

Re: Silent, nothing visible

Well, through some trial and error. I removed the UHF output bin, cleaned underneath and re soldered it all, I cleaned as best I could the traces on the bottom of the board with white vinegar, I checked and reseated several of the IC's. Innumerable checks for continuity and a wee bit of soldering......
by Colday
Sat Sep 12, 2020 1:54 pm
Forum: 8-bit acorn hardware
Topic: BBC A/B keyboards and DIP switches
Replies: 1
Views: 93

BBC A/B keyboards and DIP switches

Hi all.

DIP switches on some keyboards....

Why? What? Who?

I notice some have them and some don't.

What's the score?
by Colday
Sat Sep 12, 2020 1:50 pm
Forum: 8-bit acorn hardware
Topic: Model A Issue 7 Constant beep no keyboard
Replies: 13
Views: 388

Re: Model A Issue 7 Constant beep no keyboard

Excellent.

Turns out is was the 6522.

Replaced with a known good one. Working perfect.

Unmolested, boxed with manuals and welcome pack, BBC Model A.

Nice!
by Colday
Fri Sep 11, 2020 7:27 pm
Forum: 8-bit acorn hardware
Topic: PSU securing screws
Replies: 3
Views: 132

Re: PSU securing screws

I shall go and peruse through my box of M3 'machine screws' and see if them thar things a'fit.

Sorry, been watching a redneck on YouTube try and fix an old car.
by Colday
Fri Sep 11, 2020 7:22 am
Forum: 8-bit acorn hardware
Topic: PSU securing screws
Replies: 3
Views: 132

PSU securing screws

Morning. Does anyone have any of the little screws (or are they officially bolts if they screw into a captive nut?), anyway, does anyone have any surplus to needs? Actually need both the ones the secure the PSU to the case as well as the ones that secure the PSU board to it's metal surround. Or if a...
by Colday
Fri Sep 11, 2020 7:19 am
Forum: 8-bit acorn hardware
Topic: Which 6845?
Replies: 4
Views: 285

Re: Which 6845?

PM sent.
by Colday
Wed Sep 09, 2020 8:47 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

So, now it's working happily, I initially got the 'Language' message. When I got the beeb the Basic ROM (Actually labelled Acorn BASIC for the first time I've seen rather than PB05) was over int he far South East socket. I popped it back in that socket and all was good. Which indicates at least IC52...
by Colday
Wed Sep 09, 2020 8:37 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

I am proud to announce that I fixed it, all by myself!! I looked at the still pic I produced, could see it was the 4th line in where there was an extra pixel. I went with the flow and looked up D4 on the schematic which is either IC57 or IC65. On checking the beeb IC65 was in /CAS0 so I replaced it....
by Colday
Wed Sep 09, 2020 7:38 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

Yeah, I've just watched it myself. It's not great is it?

Here is a still of what I was trying to show.
screen1.png
by Colday
Wed Sep 09, 2020 7:11 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

IMG_4865.MOV
(4.75 MiB) Downloaded 4 times
I've no idea if this actually shows anything or not really.
by Colday
Wed Sep 09, 2020 7:04 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

So, it looks like there may be a discrepancy on the 4th vertical line from the left.

It's very hard to get a picture of cos of the CRT.
by Colday
Wed Sep 09, 2020 6:56 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

I'm watching trickys test ROM go round through it's cycle, back to Frogger then through the RAM tests again. I cannot see anything different. Does each 'flash' denote a different RAM IC or are there a number of flashes before it moves on? Doesn't help using an LCD screen to run it on. I think I will...
by Colday
Wed Sep 09, 2020 6:54 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

Is there a way I can measure individual pins on the RAM chips with scope and/or multi-meter to identify the faulty one. A oscilloscope can sometimes pick up a faulty DRAM chip. However, you do need to be experienced with using a ‘scope and you need to connect up the sync and other channels so you c...
by Colday
Wed Sep 09, 2020 6:34 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Re: Simple RAM

This doesn't exactly answer your question, but one common tactic is to use a finger to see if any one RAM chip is running hot (or indeed cold) compared to the others. And another idea is to boot Tricky's Test OS ROM. See for example software troubleshooter for beeb hardware and for example 2 dead b...
by Colday
Wed Sep 09, 2020 4:54 pm
Forum: 8-bit acorn hardware
Topic: Simple RAM
Replies: 11
Views: 262

Simple RAM

Hi all. Is there a way I can measure individual pins on the RAM chips with scope and/or multi-meter to identify the faulty one. I've got it down to /CAS0 where there is a faulty chip, I've checked each has 5v to the IC, but I don't have an inverter to be able to swap the banks over, so can't use the...
by Colday
Tue Sep 08, 2020 12:22 pm
Forum: 8-bit acorn hardware
Topic: DFS differences
Replies: 16
Views: 500

Re: DFS differences

What was the chronology of the various DFS versions? 8271, 1770, WE et al. Did the advances and compatibility merge at any point? A bit like Tolkien's one ring? One DFS to read them all, One DFS to write them, One DFS to join them all, as without it there is blindness. I've quite impressed myself th...
by Colday
Mon Sep 07, 2020 4:24 pm
Forum: 8-bit acorn hardware
Topic: RAM/ROM board battery backups
Replies: 5
Views: 208

Re: RAM/ROM board battery backups

Thanks Ken! I'll bear that all in mind.
by Colday
Mon Sep 07, 2020 4:23 pm
Forum: 8-bit acorn hardware
Topic: Someone's pinched my econet!
Replies: 14
Views: 991

Re: Someone's pinched my econet!

Fingers crossed there's no damage to the traces that I've missed. Next I need to add the spade terminals back to the board and PSU and service the sticky keyboard. The stinky power supply is now looking happy again with the usual suspects replaced. If you want some spade terminals for your beeb, PM...
by Colday
Sun Sep 06, 2020 9:16 pm
Forum: 8-bit acorn hardware
Topic: RAM/ROM board battery backups
Replies: 5
Views: 208

Re: RAM/ROM board battery backups

Ah great.

That's what I wanted to hear to be fair.

I presume 3.7v is not going to cause any issues in that range?
I have some LiOn 3.7v batteries that I was hoping to use. And now I can.
by Colday
Sun Sep 06, 2020 10:31 am
Forum: 8-bit acorn hardware
Topic: Model A Issue 7 Constant beep no keyboard
Replies: 13
Views: 388

Re: Model A Issue 7 Constant beep no keyboard

I popped the shroud back on with no issues and have refitted the VIA. Back to where I was beforehand now. Exactly the same as the start. Nice clean prompt on the screen, no LED's lit on keyboard, no keys working except the Break key which does reset the machine, constant choral Booo of the boobip (I...
by Colday
Sun Sep 06, 2020 10:26 am
Forum: 8-bit acorn hardware
Topic: Identification required please
Replies: 9
Views: 308

Re: Identification required please

Yes, there is another thread BigEd however, I do get a prompt, I don;t get the Beep of the BooBeep but the Boooo is choral. None of the LED's light up, no keys on the keyboard work except the Break key which does reset the machine, I've done further testing on the other thread. https://stardot.org.u...
by Colday
Sun Sep 06, 2020 9:21 am
Forum: 8-bit acorn hardware
Topic: Identification required please
Replies: 9
Views: 308

Re: Identification required please

Yep, that's a model A all right. Mine was a model A issue 3 board BITD. It was gradually upgraded to the full B specification. The IC sockets helped greatly with that. The first upgrade was an extra 16K RAM along with a printer interface, which needed the printer and user port connectors soldering ...
by Colday
Sun Sep 06, 2020 9:06 am
Forum: 8-bit acorn hardware
Topic: RAM/ROM board battery backups
Replies: 5
Views: 208

RAM/ROM board battery backups

Morning all. The backup batteries on the sideways RAM/ROM boards that we all remove cos they leak, what voltage should they be? Appreciate most of the Beeb runs on 5v, but is 5v as a battery backup the required voltage? Just thinking of replacing one (I have a couple of nice external ROM/RAM boards)...

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