Search found 212 matches

by johnkenyon
Wed Sep 11, 2019 9:14 am
Forum: hardware
Topic: Acorn 28-AKF17 Monitor
Replies: 21
Views: 1980

Re: Acorn 28-AKF17 Monitor

Does any one happen to have information on the rgb socket layout of the AKF17 ? Does this 9-pin-male socket differ from the common Commodore/Philips monitors then ? Or did just the Acorn 9-pin-RGB cable sort out those connections the right way as the Acorn being known for off-standards pin outs ? I...
by johnkenyon
Tue Aug 20, 2019 5:04 pm
Forum: programming
Topic: Detecting available file systems
Replies: 17
Views: 727

Re: Detecting available file systems

That's part of the psychic abilities. How does the person writing the program know that there's a filing system number 73 which is selected with the *ZEEBAR command, but must be selected with the *XEBURE command to prevent it attempting to electrocute nearby cats on selection? How did that get out ...
by johnkenyon
Tue Aug 20, 2019 10:13 am
Forum: programming
Topic: Detecting available file systems
Replies: 17
Views: 727

Re: Detecting available file systems

The proper way is to use Service Call 18 and cycle through all filing system numbers 1-255, unfortunately, DFS 0.90 doesn't respond to Service Call 18, and (if configured) ADFS tries to mount a disk. You then have to fall back on *commands, which means requiring psychic abilities, dealing with Bad ...
by johnkenyon
Tue Aug 13, 2019 9:42 am
Forum: hardware
Topic: what's the use of Mode 0
Replies: 24
Views: 906

Re: what's the use of Mode 0

cmorley wrote:
Tue Aug 13, 2019 8:09 am
80 column text.
You can do that in Mode 3.
by johnkenyon
Fri Aug 09, 2019 8:08 am
Forum: hardware
Topic: BBC Master outputs green text
Replies: 10
Views: 336

Re: BBC Master outputs green text

Thanks for the extra info 🙂 I've now tested with RF and get white text in modes 4 and 7 so moved on to look at the board. There are no obvious signs of dry joints or damaged tracks in those areas so I'll look at swapping the transistors out and go from there. If the drive transistors were weak/dyin...
by johnkenyon
Thu Aug 08, 2019 10:25 am
Forum: hardware
Topic: BBC Master outputs green text
Replies: 10
Views: 336

Re: BBC Master outputs green text

Not sure off the top of my head if the composite out on a Master is supposed to have colour but if you have an RF lead do you get colour on the UHF output? If so then the problem is with the resistors/RGB socket. If that is green too then it is the Red & Blue buffer transistors or upstream of that....
by johnkenyon
Tue Jul 30, 2019 9:00 am
Forum: hardware
Topic: High res picture of area around composite video out
Replies: 19
Views: 456

Re: High res picture of area around composite video out

Hi guys I just revived an old bbc master 128 and when I opened the case I was treated to the lovely surprise that there was a 2nd processor board fitted. I am wanting to do the modification to add a 470pf capacitor so as to make composite video into colour. As the board is perilously close to the a...
by johnkenyon
Tue Jul 30, 2019 8:31 am
Forum: software: other
Topic: Burning MOS on M27C256B
Replies: 9
Views: 284

Re: Burning MOS on M27C256B

The images at http://mdfs.net/System/ROMs/AcornMOS/Compact510/ and http://mdfs.net/System/ROMs/AcornMOS/Compact511/
are both 65536 bytes in size.

Bear in mind that the 64K ROM contains ADFS, Basic, Utils, plus MOS.
Are you sure you haven't just got the MOS bit?
by johnkenyon
Sat Jun 29, 2019 10:16 am
Forum: hardware
Topic: Trouble formatting a floppy .dsd on my Gotek
Replies: 13
Views: 438

Re: Trouble formatting a floppy .dsd on my Gotek

In the PC zone, thinking of 1.44Mb floppy discs, but bear with me Back in the mists of time, you bought blank unformatted floppies. Then (in the PC age), you bought preformatted floppies Then after nearly 20 years later, along comes the gotek, and everyone goes back to using "unformatted floppies" a...
by johnkenyon
Tue Jun 11, 2019 2:37 pm
Forum: hardware
Topic: 1770 wire links
Replies: 12
Views: 454

Re: 1770 wire links

If I don't have any spare resistor/<insert any other radial electronic component here> legs lying around the bench, I would reach for the reel of insulated single strand insulated copper wire, strip one end, cut link size+1cm, then strip the other end. Bend neatly with pliers and insert. For links l...
by johnkenyon
Tue Jun 11, 2019 10:22 am
Forum: hardware
Topic: 1770 wire links
Replies: 12
Views: 454

Re: 1770 wire links

Elminster wrote:
Tue Jun 11, 2019 9:48 am
I guess to get them as good at the ones you get in the kit you would want to heat shrink some heat shrink in the middle of your resistor leg.
Or increase the leg length (if inserted in an IC socket), or solder with an air gap between wire and PCB if being soldered in...
by johnkenyon
Tue Jun 11, 2019 9:18 am
Forum: hardware
Topic: 1770 wire links
Replies: 12
Views: 454

Re: 1770 wire links

Take a couple of resistors from that pack of 1000 you got cheap on eBay, clip the leads off, bend to the right spacing with your pliers, trim to length, install....
That's the cheap way...
by johnkenyon
Thu May 23, 2019 12:24 pm
Forum: software
Topic: How to clone a 'master' disc on Archimedes
Replies: 17
Views: 538

Re: How to clone a 'master' disc on Archimedes

Now here's a thing... Tried !Rat (!Pirat) on my A5000 last night and it crashed out and wouldn't copy the Touch Window disk. Copied the program to my A3000 and it worked perfectly making a virgin 'Master' disk which then would register to my A3000. :D Is this because the A3000 has an 800K drive and...
by johnkenyon
Tue Mar 26, 2019 11:05 am
Forum: other vintage computer hardware, software and games
Topic: Megastor 8" drive unit
Replies: 66
Views: 1969

Re: Megastor 8" drive unit

I would suggest a small AVR or PIC device.
Then you could code whatever parameters you like - delayed spinup, delayed spindown, with no rummaging around the parts bin looking for resistors or capacitors when you want to change.
by johnkenyon
Fri Mar 22, 2019 3:11 pm
Forum: hardware
Topic: Best SD card disk drive for the beeb
Replies: 9
Views: 504

Re: Best SD card disk drive for the beeb

B+ Doesn't have the HAZEL RAM that the Master uses for filing systems... d. See: http://beebwiki.mdfs.net/ANDY There's a job there for someone who wants to rewrite/extend the B+ MOS to support service calls &21, &22, &24, and supports HAZEL for calls &0F, and possibly &12. Then they'd have to tweak...
by johnkenyon
Thu Mar 21, 2019 9:29 am
Forum: other vintage computer hardware, software and games
Topic: UM1662 RF Modulator
Replies: 2
Views: 196

Re: UM1662 RF Modulator

I've also found out that the A3010 used a UM1662. Unfortunately the A3010 doesn't have a composite video output, so I can't see how the UM1662 video in differs from bog standard CVBS out. I'm struggling to find a useful Atari circuit diagram. I think I will just suck it and see. My expected problems...
by johnkenyon
Wed Mar 20, 2019 12:23 pm
Forum: other vintage computer hardware, software and games
Topic: UM1662 RF Modulator
Replies: 2
Views: 196

UM1662 RF Modulator

Whilst rummaging around a box of spares I've found a UM1662 RF modulator - It modulates video+mono sound onto channel 36 with the sound on the former UK standard 6MHz subcarrier. I can find a couple of photos of the first page of the datasheet, and absolutely nothing else. I then thought of searchin...
by johnkenyon
Mon Mar 11, 2019 2:15 pm
Forum: off-topic
Topic: RCM on the TV
Replies: 2
Views: 291

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: 865

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: 66
Views: 1969

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: 921

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: 3152

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: 324

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: 402

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: 789

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: 496

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: 496

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: 496

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: 815

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: 5409
Views: 416912

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 ...