Search found 246 matches

by johnkenyon
Fri Jul 20, 2018 6:24 pm
Forum: general
Topic: *TAPE baud rates
Replies: 24
Views: 2245

Re: *TAPE baud rates

The answer might be here: https://en.wikipedia.org/wiki/Kansas_City_standard The BBC tape interface is based on CUTS, and 300bd is the lowest common denominator. I don't know if 300baud was more reliable or not - by the time I was hacking around on BBC's my stuff was either stored on the college's L...
by johnkenyon
Fri Jul 20, 2018 6:15 pm
Forum: 8-bit acorn hardware
Topic: BBC Micro Serial ULA
Replies: 7
Views: 809

Re: BBC Micro Serial ULA

Have you tried Mark Haysman (Retroclinic)? He might well have a drawer full of serial ULAs rescued from dead boards. Mark was selling Compact serial upgrade kits on eBay so might well have some. Looking at the Master Compact circuit diagram, the only bits of the serial ULA used are the baud rate ge...
by johnkenyon
Fri Jul 20, 2018 3:04 pm
Forum: 8-bit acorn hardware
Topic: BBC Micro Serial ULA
Replies: 7
Views: 809

Re: BBC Micro Serial ULA

Has anyone reverse-engineered the serial ULA (2C199E / VC2026)? I seem to be getting a lot of machines lately with defective chips. In most cases this keeps the cassette motor turned on at all times, with pin 11 remaining high. As far as I can see, the only way to get replacements these days is to ...
by johnkenyon
Fri Jul 13, 2018 6:00 pm
Forum: 8-bit acorn hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 137
Views: 11262

Re: Cheap web-modem for the beeb/master (and arc if ya like!)

OK, I've been keeping this one to myself for too long. I've posted an annotated disassembly of the Commstar 1.40 ROM at https://stardot.org.uk/forums/viewtopic.php?f=32&t=15377 If someone wants to provide me with the strings you need to send, I'm willing to either hack together a version which will ...
by johnkenyon
Fri Jul 13, 2018 5:51 pm
Forum: archive submissions
Topic: Commstar 1.40 disassembly
Replies: 0
Views: 681

Commstar 1.40 disassembly

Here's my annotated disassembly of Commstar 1.40 Note that it's written to be assembled using the xa 6502/RC65C02/68516 cross-assembler. For the uninitiated, this means: 1) $FF not &FF for hex 2) % indicates binary (used once) 3) ROR replaces ROR A, ROL replaces ROL A, and ASL replaces ASL A To asse...
by johnkenyon
Fri Jul 13, 2018 5:31 pm
Forum: 8-bit acorn hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 137
Views: 11262

Re: Cheap web-modem for the beeb/master (and arc if ya like!)

Use commstar version 1.4. Once connected change from terminal to viewdata mode and ensure you press I and change the speeds back to 2400 before pressing C to enter chat mode again (ie connect to the modem). Commstar 2 won't work. Why don't you patch Commstar so that it starts in 2400 baud mode for ...
by johnkenyon
Thu Jun 28, 2018 11:57 pm
Forum: 8-bit acorn hardware
Topic: bbc b version finding
Replies: 3
Views: 559

Re: bbc b version finding

Note that the board issue does not tell you if it's a model A or a model B. Mark The absence of most interface connectors on the back (beyond cassette, RGB, video and RF) is usually a good indicator of a Model A, as is a missing user VIA+all underside IDC connectors. The absence of an Econet connec...
by johnkenyon
Mon Jun 18, 2018 12:33 pm
Forum: 8-bit acorn hardware
Topic: Master PSU repair - not going well
Replies: 14
Views: 1309

Re: Master PSU repair - not going well

If you are dealing with a short and want to probe around with the supply connected and without fuses popping, then use a lightbulb current limiter aka "the light bulb in series with load". Take one mains socket (preferably switched), a batten lightbulb holder, a length of 3 core mains flex and a plu...
by johnkenyon
Fri Jun 08, 2018 7:19 pm
Forum: 8-bit acorn hardware
Topic: Cassette player maintenance
Replies: 14
Views: 1001

Re: Cassette player maintenance

Many years ago I worked for a company which, amongst other things used to service cassette player modules used in TOA BA-410 background music systems. These had 1 to 4 tape modules in a 19" case, and they played crappy background music in posh food pubs that didn't want a jukebox back in the 1980s. ...
by johnkenyon
Fri Jun 08, 2018 10:17 am
Forum: 8-bit acorn hardware
Topic: Early BBC Micro's (ICL)
Replies: 9
Views: 1400

Re: Early BBC Micro's (ICL)

Here's my issue 2 model A, Cleartone manufactured, serial 100403 and all chips socketted which is very nice :) It's in great condition, so I don't want to modify (other than easily reversible) but it is rather limited without any ports...! I'm currently working up a reliable and reversible fitment ...
by johnkenyon
Thu Jun 07, 2018 4:38 pm
Forum: 8-bit acorn hardware
Topic: ECONET WOES
Replies: 74
Views: 6900

Re: ECONET WOES

Thanks John, means nothing to me though, I don’t do networks - I was just trying to help Darren with the question... :lol: One point of clarification, you said OSWORD &14 but the RTC call RAMagic supports is OSWORD 14 (decimal) or &0E. Maybe you meant &14 because that’s an NFS functions call but it...
by johnkenyon
Thu Jun 07, 2018 3:01 pm
Forum: 8-bit acorn hardware
Topic: ECONET WOES
Replies: 74
Views: 6900

Re: ECONET WOES

I could be completely wrong here but I don't think you can 'remotely read' the RTC dongle from a station, not a lot (as I have understood anyway) is known about it really. Darren doesn’t have a User Port RTC dongle, he has one of my RAMagic units which, amongst other things, includes a sideways rom...
by johnkenyon
Mon Jun 04, 2018 5:14 pm
Forum: 8-bit acorn hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 137
Views: 11262

Re: Cheap web-modem for the beeb/master (and arc if ya like!)

Just a thought of mine will look at this weekend unless anyone else has? Just pure laziness but has anyone moded the commstar Rom image to default the send and receive and parity options to N81 9600 ? Just saves the time! I’ve moded Daniels Sketch to add a ATMYFI command that adds in my ssid etc an...
by johnkenyon
Tue May 22, 2018 10:00 am
Forum: wanted
Topic: Wanted Prestel Adapter
Replies: 7
Views: 984

Re: Wanted Prestel Adapter

That is a very kind offer, I have sent a message to John Kenyon in the hope of purchasing his, however, if for any reason that doesn't work out, I may take you up on your offer. I am particularly interested in the signalling that occurs on the RTS/CTS lines for dialling and call set up etc. The Aco...
by johnkenyon
Sun May 20, 2018 12:39 pm
Forum: wanted
Topic: Wanted Prestel Adapter
Replies: 7
Views: 984

Re: Wanted Prestel Adapter

I have one - PM me with an offer (letting me know your location), noting that I won't be able to ship it for at least a fortnight.

/John
by johnkenyon
Fri May 04, 2018 12:16 am
Forum: 8-bit acorn hardware
Topic: TEAC FD55V floppy phototransistor
Replies: 8
Views: 917

Re: TEAC FD55V floppy phototransistor

Any chance of some dimensions?
Outside diameter
Depth (base to start of dome)
Depth (base to tip of dome)
The electrical characteristics of a replacement device are probably secondary to how big the thing is.
/john
by johnkenyon
Thu May 03, 2018 9:26 pm
Forum: 8-bit acorn hardware
Topic: EPROM programmer
Replies: 18
Views: 1892

Re: EPROM programmer

1024MAK wrote: [Some units don't prevent the UV light from escaping, so if light does leak out, don't look at the light!!!
But it's so beautiful...
(I'll get my coat)
by johnkenyon
Thu Apr 19, 2018 7:06 pm
Forum: 8-bit acorn hardware
Topic: SWRAM protection at power down
Replies: 8
Views: 1128

Re: SWRAM protection at power down

The back in the day solution would be to copy the ATPL Sidewise board had a brown out protection circuit which prevented spurious RAM writes. A look at page 6 the battery backup installation manual may help: http://8bs.com/othrdnld/manuals/hardware/ATPLBatteryBackup_pdf.zip This did a pull down on o...
by johnkenyon
Fri Apr 13, 2018 12:12 am
Forum: 8-bit acorn hardware
Topic: ECONET WOES
Replies: 74
Views: 6900

Re: ECONET WOES

Refer to the BBC B circuit diagram at http://mdfs.net/Info/Comp/BBC/Circuits/BBC/bbc.gif top left hand corner. Recheck the Econet installation see: https://www.beebmaster.co.uk/BeebShop/Downloads/BeebMaster%20Econet%20Upgrade%20Kit%20Fitting%20Instructions%20v2-5.pdf Double check all resistor values...
by johnkenyon
Sat Mar 31, 2018 3:14 pm
Forum: general
Topic: Today I received.....
Replies: 5956
Views: 588042

Re: Today I received.....

I was thinking about adding a voltage regulator to allow the clock to be safely powered from a Beeb auxiliary power port.... My Econet is only small at the moment, but it is growing, and my plan is to have separate 8bit and 32bit nets linked via a bridge :D You've already got a +5v supply on the BB...
by johnkenyon
Tue Mar 27, 2018 11:19 am
Forum: 8-bit acorn hardware
Topic: Capacitor size
Replies: 5
Views: 584

Re: Capacitor size

As a follow on, for radial capacitors (where the 2 leads stick out of the same end), if the pitch of the leads doesn't match the pitch on the board, the recommendation back in the day was that you keep the positive lead straight, and only bend the negative lead, on the basis that (1) you only bend o...
by johnkenyon
Mon Mar 12, 2018 9:52 am
Forum: wanted
Topic: WTD: NTSC Compatible TV
Replies: 8
Views: 1169

Re: WTD: NTSC Compatible TV

Hi Guys, I have aquired a US NES for playing Tetris but need a compatible TV for it, preferably under 20". Had a look in the usual places but no joy. Anyone got any ideas or a set hanging around they would be happy to part with? thanks nOm If the NES has a composite video (yellow RCA/phono jack) ou...
by johnkenyon
Thu Mar 08, 2018 4:58 pm
Forum: 8-bit acorn hardware
Topic: 5.25" Drive Cleaning Kit
Replies: 27
Views: 2286

Re: 5.25" Drive Cleaning Kit

A google for "chamois cleaning swabs" (without the quotes) gives you a few options.

As for cleaning fluids, a bottle of IPA/iso-propyl alcohol/propan-2-ol from the local chemist was always my solvent of choice for tape heads back in the day.

/john
by johnkenyon
Sat Feb 24, 2018 2:11 am
Forum: archive submissions
Topic: Logotron Logo - Welsh version
Replies: 9
Views: 2118

Logotron Logo - Welsh version

I've found this version of Logotron Logo - original label on the EPROM, looked like a match for http://mdfs.net/System/ROMs/Graphics/ACTLOGO100 However after running the image through the Unix/Linux "strings" command I see things like "CROESO I LOGO_C" and "rhif rhy uche" which Google translate tell...
by johnkenyon
Fri Feb 23, 2018 5:55 pm
Forum: archive submissions
Topic: Prestel and Teletext Adaptor ROMs
Replies: 2
Views: 854

Re: Prestel and Teletext Adaptor ROMs

Here's a zip file with the four images.

/John
by johnkenyon
Fri Feb 23, 2018 4:58 pm
Forum: archive submissions
Topic: Prestel and Teletext Adaptor ROMs
Replies: 2
Views: 854

Prestel and Teletext Adaptor ROMs

Whilst digging through a box of old stuff, I found the following four ROMs which I've "imaged". The first one appears to be an early version for the Prestel Adaptor (the version on mdfs.net is v1.10) PRS-1.00: PRESTEL 1.00 (C)1984SofMac The next three appear to be an early version of what became ATS...
by johnkenyon
Thu Feb 22, 2018 9:29 am
Forum: 8-bit acorn hardware
Topic: Solidisk Tic-Toc RTC
Replies: 34
Views: 7879

Re: Solidisk Tic-Toc RTC

Have to smile, it assumes 20th century, ie. Feb 1918!! Reading manual, shows the various registers, there's not one for century as best I can tell. Not sure whether it's good or not our friend Jon's HADFS60 doesn't pick up date from Tic-Toc as it does in the Master, albeit not tried Jon's fsys on m...
by johnkenyon
Tue Feb 20, 2018 11:07 am
Forum: 8-bit acorn hardware
Topic: BeebSCSImini
Replies: 45
Views: 4598

Re: BeebSCSImini

the machine hangs at the Acorn ADFS message The usual reason for this is that ADFS uses an odd type of detection on boot to see if the SCSI card is present. Basically it sends a pattern of data which (if a board is connected) it can read back from one of the data latches on the board. BeebSCSI emul...
by johnkenyon
Mon Feb 19, 2018 3:38 pm
Forum: 8-bit acorn software: other
Topic: Hacking the school Econet
Replies: 24
Views: 2982

Re: Hacking the school Econet

My technique was to keep my eyes peeled for one of the two teachers leaving the Network Manager menu program on an unattended computer. The sequence then went something like. 1) Hit break on the computer logged in with a privileged account. 2) *PRIV <myid> S 3) Hit break again 4) Move to another com...
by johnkenyon
Sat Feb 10, 2018 7:51 pm
Forum: other vintage hardware, software and languages
Topic: Solutions for a sheered screw
Replies: 11
Views: 1138

Re: Solutions for a sheered screw

danielj wrote:I'm wondering if I can just unfill the old head, unscrew it and do as Mark said. I can't work out what size screw it was - it seems to be 4.4mm diameter... That doesn't seem to correlate to anything?

d.
Possibly a BA thread/screw?

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