Search found 6644 matches

by 1024MAK
Wed Oct 18, 2017 2:48 am
Forum: hardware
Topic: BBC Model B takes up smoking
Replies: 34
Views: 797

Re: BBC Model B takes up smoking

As I understand it, moisture getting in to the capacitors, and/or large numbers of high voltage mains spikes, helps to kill them. The plastic package should stop moisture getting in, but if it becomes damaged... If you do suspect mains spikes, use a good quality extension socket that contains VDRs. ...
by 1024MAK
Tue Oct 17, 2017 10:56 pm
Forum: general
Topic: Beeb Spotting
Replies: 15
Views: 1389

Re: Beeb Spotting

Were those disks double the capacity of the 3 inch type :lol:

Mark
by 1024MAK
Tue Oct 17, 2017 1:29 pm
Forum: hardware
Topic: Resurrecting a BBC-B, and running with it!
Replies: 7
Views: 134

Re: Resurrecting a BBC-B, and running with it!

The *ROMS command is not included in a BBC Micro. Unless a third party ROM provides a *ROMS command. So when you type *ROMS, the DFS is looking for a file with the same name on the currently selected disk... hence what appears to be a hang... However, *ROMS is a valid command on the Master range of ...
by 1024MAK
Tue Oct 17, 2017 1:07 pm
Forum: hardware
Topic: Mystery object, fits Econet socket
Replies: 18
Views: 230

Re: Mystery object, fits Econet socket

If the size of the image/picture/photo is below a certain size, the forum software will not create a 'thumbnail' image. In this case, click on the highlighted link in the preview display window, which will display the image, then copy this URL. Now go back (back button) to the post, use the Img tag ...
by 1024MAK
Tue Oct 17, 2017 12:09 pm
Forum: software: other
Topic: Z80 on a BBC B
Replies: 30
Views: 245

Re: Z80 on a BBC B

The Torch is slightly different as it does not do things in the same way as the Acorn second processor systems. With the Acorn second processor systems, when the OS in the BBC Micro detects the ROM in the BBC, that ROM then checks for a second processor, it can then "transfer" control to ...
by 1024MAK
Tue Oct 17, 2017 7:15 am
Forum: software: other
Topic: Z80 on a BBC B
Replies: 30
Views: 245

Re: Z80 on a BBC B

The Torch is slightly different as it does not do things in the same way as the Acorn second processor systems. With the Acorn second processor systems, when the OS in the BBC Micro detects the ROM in the BBC, that ROM then checks for a second processor, it can then "transfer" control to t...
by 1024MAK
Mon Oct 16, 2017 1:53 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 16
Views: 560

Re: Electron ULA Schematics

CKxRST1 and CKxRST2 may be some kind of clocked reset pulse, but guessing is not always reliable :mrgreen: MONOINX, MONOOUT - I don't think it very likely that "audio" would be described as mono in a system that was never intended to have stereo sound. Therefore it's very likely that the s...
by 1024MAK
Mon Oct 16, 2017 1:47 pm
Forum: hardware
Topic: 6502 second processor poll
Replies: 36
Views: 748

Re: 6502 second processor poll

I doubt you will get a true proportion of people having/not having a 2p. Logically people who don't have one don't want to bother doing effort for what they don't have, and those who do have one will have a desire to 'show off' what they have (don't deny it, it's true!)... But in the real world, AL...
by 1024MAK
Mon Oct 16, 2017 1:31 pm
Forum: hardware
Topic: BBC Model B takes up smoking
Replies: 34
Views: 797

Re: BBC Model B takes up smoking

Ah when I did the Master, it was left for a number of days but I was still a bit weary :) So you touch the points of a single capacitor together? Yes, you short the pair of two pads/leads of the first capacitor to each other. Then do the same for the other capacitor. Try to short across the bits of...
by 1024MAK
Mon Oct 16, 2017 11:49 am
Forum: hardware
Topic: BBC Model B takes up smoking
Replies: 34
Views: 797

Re: BBC Model B takes up smoking

How long could a BBC PSU capacitor hold a charge for? When I did the ones in my Master I left it turned off for a day, flicked switch on and off etc. I'm still very wary of working on electronics. In general, there isn't a simple answer to this, as it depends on the circuit, the voltage and the cap...
by 1024MAK
Mon Oct 16, 2017 11:20 am
Forum: hardware
Topic: 6502 second processor poll
Replies: 36
Views: 748

Re: 6502 second processor poll

I doubt you will get a true proportion of people having/not having a 2p. Logically people who don't have one don't want to bother doing effort for what they don't have, and those who do have one will have a desire to 'show off' what they have (don't deny it, it's true!)... But in the real world, AL...
by 1024MAK
Sun Oct 15, 2017 11:24 pm
Forum: wanted
Topic: WTB 6 x 2114 SRAM
Replies: 3
Views: 82

Re: WTB 6 x 2114 SRAM

Hi Jon

I've found these to be okay: 10pcs TC5514APL-3 TOSHIBA Encapsulation DIP-18. They are direct equivalents (except much lower power) to 2114L chips.
eBay item no. 391241285361

Mark
by 1024MAK
Sun Oct 15, 2017 5:54 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 19
Views: 366

Re: Open Source Logic Analyzer Experiments

The last thing to report is that yesterday Ed pointed out that the 6502 annotations seemed to lag the bus signals by one cycle. So the Fetch cycle didn't actually line up with SYNC being high. That explains why it did not conform to my expectations of how a 6502 works and why there was a bit of puz...
by 1024MAK
Sun Oct 15, 2017 5:48 pm
Forum: for sale / freebies
Topic: Monitor, cables, ARM2s, RISC OS ROMs, and more
Replies: 7
Views: 214

Re: Monitor, cables, ARM2s, RISC OS ROMs, and more

Whoops! :oops: #-o

My fault. I forgot to actually send it :oops:
You should have it now...

When you send a PM, it will sit in your 'Outbox' until the recipient opens it. Then it will be moved to your 'Sent' box.

Mark
by 1024MAK
Sun Oct 15, 2017 2:40 pm
Forum: for sale / freebies
Topic: Monitor, cables, ARM2s, RISC OS ROMs, and more
Replies: 7
Views: 214

Re: Monitor, cables, ARM2s, RISC OS ROMs, and more

You should have PM privileges.

See if you can reply to the test PM I just sent to you.

Mark
by 1024MAK
Sun Oct 15, 2017 12:56 pm
Forum: hardware
Topic: CUB 451 with lots of interference
Replies: 26
Views: 592

Re: CUB 451 with lots of interference

Had a diode in the switch mode go too, fast recovery schottkey (apologies for speeling) replaced with 1N4004 That part is just not up to the job! It's a FAST recovery schottky diode for a reason . . . Dave h :D Yep, a 1N4004 (or any 1N400x diode) will be too slow. This series is designed for rectif...
by 1024MAK
Sun Oct 15, 2017 12:39 pm
Forum: hardware
Topic: Electron ULA Schematics
Replies: 16
Views: 560

Re: Electron ULA Schematics

If a high resolution grey scale scan could be done, then an image editing program may be able to improve the contrast of some of the hard to read detail.

Mark
by 1024MAK
Sun Oct 15, 2017 8:58 am
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 19
Views: 366

Re: Open Source Logic Analyzer Experiments

Thank you Dave and Ed, some excellent work there =D> =D> =D>

I will have to dig out my Open Bench Logic Sniffer again and have a play :mrgreen:

Mark
by 1024MAK
Sat Oct 14, 2017 11:59 pm
Forum: hardware
Topic: LCD TVs and monitors for use with BBCs
Replies: 183
Views: 49199

Re: LCD TVs and monitors for use with BBCs

Thanks for info. Bought 8820 for £20, old TV at charity shop for £10, cardboard box 8220 packed in for free, and brilliant results. Few little flashing spots only when screen full of text hardly noticeable, else black. Great job! New Master on left with video board, original B on right running Soli...
by 1024MAK
Fri Oct 13, 2017 8:13 pm
Forum: general
Topic: Today I received.....
Replies: 4202
Views: 223518

Re: Today I received.....

danielj wrote:You will be needing, at the very least, a plus one, and AP5, and mega-games cartridge ;)

Before that a cassette lead :)

d.

You will be needing a plentiful supply of PayPal funds to transfer to a certain member here who produces lots of goodies for Elks... :wink:

Mark
by 1024MAK
Fri Oct 13, 2017 7:33 am
Forum: hardware
Topic: SJ MDFS server circuit diagram/schematic
Replies: 32
Views: 2212

Re: SJ MDFS server circuit diagram/schematic

I made a start at colouring in some of the interconnections to make it slightly easier to understand, I posted the picture in this post :wink:

Mark
by 1024MAK
Thu Oct 12, 2017 11:06 pm
Forum: hardware
Topic: 6502 second processor poll
Replies: 36
Views: 748

Re: 6502 second processor poll

Yes - Original 6502 external second processor
Yes - Master internal co-processor
Yes - Internal remake for Master
Yes - Matchbox

Mark
by 1024MAK
Thu Oct 12, 2017 11:00 pm
Forum: off-topic
Topic: Megadrive 1 power regulators
Replies: 12
Views: 196

Re: Megadrive 1 power regulators

It's not really a surprise that the input terminals are linked, or that the 0V/common/ground terminals are linked.

If you use a multimeter on resistance, test between the output terminals, one lead on each output leg. If the result is more than say 500 ohms, they are not linked :wink:

Mark
by 1024MAK
Thu Oct 12, 2017 12:04 pm
Forum: software: other
Topic: Variants of ADFS
Replies: 12
Views: 337

Re: Variants of ADFS

Well, back in the real world, DFS fitted in a 8k byte ROM. It is a filing system for floppy drives only. And at the time, floppy drives and the floppy drive interface cost a fortune. ADFS was then developed. This came on a 16k byte ROM. Although floppy drives and the interface had fallen in price, t...
by 1024MAK
Thu Oct 12, 2017 11:42 am
Forum: off-topic
Topic: Megadrive 1 power regulators
Replies: 12
Views: 196

Re: Megadrive 1 power regulators

I think you know the answer... [-X Mark Thanks. I have tried to get out of the habit of assuming... I generally seem to get it wrong! :oops: I did think I had read somewhere about the Z80 but then assumed I had imagined it. Sleep deprivation does weird things to the brain. :? Just check that the ex...
by 1024MAK
Thu Oct 12, 2017 11:37 am
Forum: other vintage computer hardware, software and games
Topic: Early 70s Calculators
Replies: 34
Views: 1559

Re: Early 70s Calculators

I should add that the fx-451 keyboard is a bit mucky 'cus it still gets used on a regular basis, even when there is a computer, Psion, iPhone and iPad mini within reach :D

Although these days I never fold the "case" shut anymore, it just stays open and flat like in the photos.

Mark
by 1024MAK
Thu Oct 12, 2017 11:22 am
Forum: other vintage computer hardware, software and games
Topic: Early 70s Calculators
Replies: 34
Views: 1559

Re: Early 70s Calculators

My perception from BITD: Sinclair: remarkable Commodore: affordable TI: capable HP: unattainable For some reason, Casio and Sharp didn't pique my interest much. Later on, I came to like Sharp. From my perspective, it was rather different... At school when I discovered that electronic calculators ex...
by 1024MAK
Thu Oct 12, 2017 10:06 am
Forum: off-topic
Topic: Megadrive 1 power regulators
Replies: 12
Views: 196

Re: Megadrive 1 power regulators

I think you know the answer... [-X Either use a RECOM or a TRACO type like in the links below, they can be used to replace 7805 voltage regulators in most applications :wink: . Prices on these DC/DC converters/regulators often change, so also check the prices of other suppliers ;) Here are some part...
by 1024MAK
Thu Oct 12, 2017 7:33 am
Forum: introduce yourself
Topic: Acorn Atom not working
Replies: 45
Views: 636

Re: Acorn Atom not working

Dave If you use a laptop to load and save games etc. does it matter if the ground connections for the microphone and earphone connections on the laptop are joined together? John In all modern equipment, the microphone and earphone connections will use the same internal 0V/ground. The Atom uses the ...
by 1024MAK
Wed Oct 11, 2017 11:32 am
Forum: announcements
Topic: Server Updates
Replies: 4
Views: 1052

Re: Server Updates

Phew!...

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