Search found 195 matches

by johnkenyon
Mon Mar 11, 2019 2:15 pm
Forum: off-topic
Topic: RCM on the TV
Replies: 2
Views: 160

Re: RCM on the TV

I just saw an announcement on the local BBC news that the RCM is going to be on "Inside Out" East Midlands tonight as they cover the "craze" of collecting old home computers. I'm guessing that the show will appear on the following link sometime after 8:30pm tonight (11th March) for everyone that do...
by johnkenyon
Fri Mar 08, 2019 8:17 am
Forum: hardware
Topic: Rom daughterboard
Replies: 19
Views: 475

Re: Rom daughterboard

1. IC76 You need to fit a 74LS163 (BBC B Circuit diagram and others here: http://mdfs.net/Info/Comp/BBC/Circuits/ look for bbc.gif ) Note that the header from the daughterboard may have spread out the contacts making an IC a loose fit. The fix is either to replace the socket, or if you want to avoid...
by johnkenyon
Tue Mar 05, 2019 5:02 pm
Forum: other vintage computer hardware, software and games
Topic: Megastor 8" drive unit
Replies: 17
Views: 498

Re: Megastor 8" drive unit

What's the 40 pin device?
(Edit: Cancel that question - found this https://www.mirrorservice.org/sites/www ... manual.pdf
and it says "Large Scale Integrated Circuit BASF 81041-001")

And have you located a replacement?
by johnkenyon
Sat Mar 02, 2019 12:23 am
Forum: hardware
Topic: Am I a Monster?
Replies: 22
Views: 622

Re: Am I a Monster?

I replaced the BNC connector on one of my Beebs with a chassis phono socket. BNC connectors are reserved for test gear and 10base2 as far as I'm concerned. Unhappy memories of numerous broken composite video cables at school, and spending half your lunchtime trying to get a working picture...
by johnkenyon
Mon Feb 25, 2019 6:18 pm
Forum: off-topic
Topic: Stag Orbit 32 Programmer
Replies: 21
Views: 2650

Re: Stag Orbit 32 Programmer

Mine kept shutting down about 45 seconds after being powered up. Problem was caused by a botched/leaky battery pack. The battery pack died, and electrolyte from the batteries wicked up the lead and rotted the molex contact. It then continued to rot a track on the PCB. Luckily I could trace where it ...
by johnkenyon
Sat Feb 23, 2019 1:11 pm
Forum: wanted
Topic: Off Topic Wanted: Vintage Sound Blaster & Roland MT32
Replies: 3
Views: 169

Re: Off Topic Wanted: Vintage Sound Blaster & Roland MT32

I've got a CT3990 AWE32 PNP...
by johnkenyon
Sat Feb 23, 2019 1:03 pm
Forum: hardware
Topic: Help - scart output
Replies: 6
Views: 279

Re: Help - scart output

Does your scart lead have the required resistors installed?
I'm wondering if the screen is having problems handling the sync signal.
by johnkenyon
Thu Feb 21, 2019 1:22 pm
Forum: hardware
Topic: Sideways Ram
Replies: 23
Views: 550

Re: Sideways Ram

What Roms/utils do I need to get sideways rom/ram working? *ROMS doesn't work for me at all. *SRLOAD doesn't either. I've got a Watford Electronics 12 ROM board with RAM in position 14. Aside: It's also got provision for a solder-on battery. I have no idea what voltage it needs to be (the instructi...
by johnkenyon
Mon Feb 18, 2019 2:47 pm
Forum: hardware
Topic: i-Cubed EtherLan 500 circuit diagram or good photo
Replies: 7
Views: 320

Re: i-Cubed EtherLan 500 circuit diagram or good photo

Great, thank you for all the replies - that's really helpful, and I think with a combination of the data sheet, the better photo and a general knowledge of how Ethernet transceivers behave I should be able to get the values right. The extra components look like they're just decoupling for the trans...
by johnkenyon
Sun Feb 17, 2019 4:05 pm
Forum: hardware
Topic: i-Cubed EtherLan 500 circuit diagram or good photo
Replies: 7
Views: 320

Re: i-Cubed EtherLan 500 circuit diagram or good photo

More digging. The MX98902 is equivalent to the NS83902. The only thing I can find which uses the NS83902 is an IBM "PPC403GCX Evaluation Board". If you can find the documentation for that board, you might also get a schematic thrown in for free. Details of the HALO FD12-101G magnetics can be found a...
by johnkenyon
Sun Feb 17, 2019 3:07 pm
Forum: hardware
Topic: i-Cubed EtherLan 500 circuit diagram or good photo
Replies: 7
Views: 320

Re: i-Cubed EtherLan 500 circuit diagram or good photo

First result after a bit of digging: https://commons.m.wikimedia.org/wiki/File:Acorn_AEH75_Access%2B_A5000_(top).jpg Possibly copied from/originally taken for: http://chrisacorns.computinghistory.org.uk/Network/Pics/Acorn_AEH75_Access+.html Better: http://www.computinghistory.org.uk/det/33963/i-cube...
by johnkenyon
Sat Feb 16, 2019 12:17 pm
Forum: hardware
Topic: My new beeb - A to B? But why no analogue?
Replies: 19
Views: 622

Re: My new beeb - A to B? But why no analogue?

The ADC socket looks like it's been installed and removed.
It's also got a speech synth upgrade installed - TMS5220 + TMS6100.
by johnkenyon
Wed Feb 13, 2019 7:05 pm
Forum: general
Topic: Today I received.....
Replies: 5058
Views: 369581

Re: Today I received.....

What is it? What does it do? Enquiring minds want to know! This enquiring mind also wants to know :lol: No software or documentation as of yet... The TMS320 is a series of digital signal processors. (aka DSP) You've probably bought yourself a programmable audio filter. You'll have fun getting that ...
by johnkenyon
Sun Feb 03, 2019 12:27 pm
Forum: hardware
Topic: Tube port fault?
Replies: 7
Views: 350

Re: Tube port fault?

Hello again! No news 'till today. I replaced the near 6522 but with no result. I unplugged all the eproms except from Basic and OS, i placed a NFS(I tried also a DNFS eprom) eprom, but with no avail. I get the same symptom when i just plug the flat cable. What i am trying to do, is to use a PiTubeD...
by johnkenyon
Wed Jan 30, 2019 11:34 am
Forum: hardware
Topic: Issue 6 Acorn Electron
Replies: 17
Views: 637

Re: Issue 6 Acorn Electron

I wonder if it would be possible to install this mod internally, by removing R45, R46, R47, connecting the left hand pad (on the schematic, the one connected to the ULA) to the gate inputs, and the outputs to the right hand pad, through some replacement 68R resistors. You would of course need flyin...
by johnkenyon
Sun Dec 02, 2018 5:47 pm
Forum: hardware
Topic: Loss of output on Electron RGB Port
Replies: 24
Views: 579

Re: Loss of output on Electron RGB Port

1024MAK wrote:
Sun Dec 02, 2018 5:43 pm
By default, both the BBC B and the Electron only output a monochrome (black and white) video signal on the composite video outputs.

Mark
Fitting LK4 should add chroma to the video output.
by johnkenyon
Sat Dec 01, 2018 12:36 am
Forum: hardware
Topic: Econet clock?
Replies: 15
Views: 615

Re: Econet clock testing...

Using *notify I tried to send a message across, but no luck. :? Should this work or is a socket box needed for this setup? Have you got NOTIFY on disk or in ROM? ... It seems I may have the basics wrong. I (probably wrongly) assumed that *notify was an NFS command contained in the NFS rom. *help is...
by johnkenyon
Sat Nov 24, 2018 1:38 pm
Forum: wanted
Topic: DS3691 RS423 Line Driver
Replies: 2
Views: 220

Re: DS3691 RS423 Line Driver

Have you googled for AM26LS30 which AFAIK is the same part/pin compatible?
by johnkenyon
Tue Nov 20, 2018 11:28 am
Forum: hardware
Topic: Econet clock?
Replies: 15
Views: 615

Re: Econet clock?

Looking at the other side of the pcb it seems there are even more similarities. Looks like someone's brewed copied the original clock PCB, added a track to permanently select one speed and left the link holes undrilled. I love the way the tracks from the transformer secondary pass oh so close to th...
by johnkenyon
Thu Oct 25, 2018 9:54 am
Forum: hardware
Topic: BBD B+ Issues..please help
Replies: 24
Views: 939

Re: BBD B+ Issues..please help

Elminster wrote:
Thu Oct 25, 2018 8:19 am
Could be a crack track or a cold joint, that could cause intermit/self fixing issue.
Or a socketed device being moved microscopically in a tarnished socket by contraction/expansion?
by johnkenyon
Fri Oct 19, 2018 10:38 am
Forum: hardware
Topic: PCF8583 breakout board
Replies: 7
Views: 388

Re: PCF8583 breakout board

For the through hole Archimedes machines, I designed this a couple of years ago. https://stardot.org.uk/forums/viewtopic.php?f=16&t=10968 It simply, replaces a borked through hole version with a SMT version of the same chip and provides I2C as a breakout. It does depend on the basic functionality o...
by johnkenyon
Thu Oct 18, 2018 6:10 pm
Forum: hardware
Topic: PCF8583 breakout board
Replies: 7
Views: 388

Re: PCF8583 breakout board

A bit like this - http://www.cjemicros.co.uk/micros/individual/newprodpages/prodinfo.php?prodcode=CJE-RTCPOD ?? I was thinking something a bit more generic/"maker"/arduino/RPi-ish. Preferably using a CR2032 (and no charging) or having two pads to connect to an "off board", out of harms way AAA base...
by johnkenyon
Thu Oct 18, 2018 1:44 pm
Forum: hardware
Topic: PCF8583 breakout board
Replies: 7
Views: 388

PCF8583 breakout board

Given the number of A5000's (and others) suffering from battery damage near the RTC chip, wouldn't it make more sense to remove the goosed device from the motherboard and then wire in a "PCF8583+crystal+coin cell battery" on a board. You might even be able to get away with connecting it to the i2c i...
by johnkenyon
Tue Oct 16, 2018 9:37 am
Forum: hardware
Topic: BBD B+ Issues..please help
Replies: 24
Views: 939

Re: BBD B+ Issues..please help

OK... I think I found something. I hooked up my logic analyser to IC30 and I can see the following data on the outputs: That seems to indicate that the 3rd bit is stuck high. The 3rd bit seems to correspond to Q2. Looking at the output of Q2 it starts low, and at power-up it jumps high and just sta...
by johnkenyon
Fri Oct 12, 2018 12:12 pm
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 447

Re: Master 128 SCART Fun

So the idea is that each diode drops about 0.65Vs? Wouldnt you traditionally use a zenner to clamp the voltage instead? You traditionally use what's in your spares box first. For me, 1N4148 diodes, generic small signal NPN (e.g. BC109, 2N2222 etc), and PNP (e.g. BC179, 2N2907) transistors are all "...
by johnkenyon
Tue Sep 25, 2018 10:31 am
Forum: hardware
Topic: New econet setup
Replies: 75
Views: 1928

Re: New econet setup

The BBC B library should go to $.LIBRARY The Master library files should go in $.LIBRARY1 If you're copying from an ADFS utilities/fs disc, it's a one for one copy - $.LIBRARY to $.LIBRARY Note that you will have to change the access rights on these files - by default they will probably be WR/, henc...
by johnkenyon
Tue Sep 25, 2018 9:33 am
Forum: hardware
Topic: New econet setup
Replies: 75
Views: 1928

Re: New econet setup

The "Bad command" is because you don't have the "FS" command in the library directory on the file server. If you were using a Master 128 as a client, you wouldn't see this, because FS is built in to ANFS. The simple fix for all this is to hit return when prompted for the file server number. This has...
by johnkenyon
Tue Sep 25, 2018 1:59 am
Forum: hardware
Topic: New econet setup
Replies: 75
Views: 1928

Re: New econet setup

You entered 0 for the file server - you should have entered 254.
by johnkenyon
Wed Sep 19, 2018 2:37 pm
Forum: hardware
Topic: New hardware suggestion - Pi econet server
Replies: 51
Views: 2217

Re: New hardware suggestion - Pi econet server

I would suggest taking the circuit diagram for the Master Econet module, and replacing the ADLC with a bit banging Pi Zero. That would require 3 inputs: clock, data in, "clock present", and two outputs: Data out, and transmit driver enable. There is a lot of circuitry relating to collision detectio...
by johnkenyon
Tue Sep 18, 2018 6:12 pm
Forum: hardware
Topic: New econet setup
Replies: 75
Views: 1928

Re: New econet setup

My Master is going to be the file server. Does it matter what its station number is? Are there reserved numbers that should be used for the file store? I have downloaded a bunch of econet docs but only skim read them so far. Usual practice back in the day was to use station 254 for the 1st file ser...