Search found 6854 matches

by 1024MAK
Fri Jan 19, 2018 10:52 pm
Forum: upcoming and recent events & exhibitions
Topic: RISC OS SouthWest Show 2018 - Saturday 24th February, 2018
Replies: 0
Views: 3

RISC OS SouthWest Show 2018 - Saturday 24th February, 2018

RISC OS SouthWest Show 2018 - Saturday 24th February, 2018

Image

Web site http://www.riscos-swshow.co.uk
by 1024MAK
Fri Jan 19, 2018 9:52 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

danielj wrote:I'll be joining you all bright and early :) Let me know if there's any bits and bobs needed! :)

d.

Ian has requested some help with repairs... so bring your entire workshop!

Mark
by 1024MAK
Fri Jan 19, 2018 7:07 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

Arcadian wrote:Everybody else in the Bridgewater! :)

Yes, currently plenty of room, just three of us so far...

Mark
by 1024MAK
Fri Jan 19, 2018 3:42 pm
Forum: hardware
Topic: Large project box
Replies: 5
Views: 215

Re: Large project box

If you want a plastic rectangular box with a flat top, search for 19 inch rack plastic boxes.

E.g. On eBay "Black 19 Inch ABS Plastic Rack Mount Case Box Enclosure"

Mark
by 1024MAK
Thu Jan 18, 2018 10:40 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

Why can you never find what you want when your time is limited... :shock: :(

Mark
by 1024MAK
Thu Jan 18, 2018 9:47 pm
Forum: other vintage computer hardware, software and games
Topic: Reading EPROMS
Replies: 10
Views: 241

Re: Reading EPROMS

/OE (negative logic output enable) turns on the three state drives on the output pins, while /CE or /CS (negative logic chip enable or chip select) brings it out of "standby" mode and tells it to read it's memory. So normally /CE or /CS is connected to address decoder logic and /OE is conn...
by 1024MAK
Thu Jan 18, 2018 4:08 pm
Forum: other vintage computer hardware, software and games
Topic: Reading EPROMS
Replies: 10
Views: 241

Re: Reading EPROMS

The data area of an EPROM is actually analog. Comparators actually decide if each memory cell is a zero or a one based on the voltage from the cell. The rest of the circuitry is either NMOS or CMOS logic circuits, with the CPU interface designed to be compatible with 5V TTL logic (for the smaller/ol...
by 1024MAK
Thu Jan 18, 2018 3:54 pm
Forum: other vintage computer hardware, software and games
Topic: Reading EPROMS
Replies: 10
Views: 241

Re: Reading EPROMS

You may find that it works with a 3.3V supply voltage (well, for reading, not recommended for programming). Unless the original programming was marginal (in which case some cells may return incorrect data). It may also not meet the datasheet timing values.

Mark
by 1024MAK
Wed Jan 17, 2018 8:14 pm
Forum: hardware
Topic: Newbie question regarding first machine
Replies: 16
Views: 428

Re: Newbie question regarding first machine

The Master series were Acorn's last 8 bit machines, in the same way that Amstrad's Sinclair +2B/+3B were the last of the Sinclair Spectrum range. Although the Model B is more advanced than a Sinclair Spectrum+ in many ways, the Spectrum has the advantage of more RAM and a display system that is more...
by 1024MAK
Tue Jan 16, 2018 11:42 pm
Forum: off-topic
Topic: Decoupling capacitor for ic
Replies: 11
Views: 295

Re: Decoupling capacitor for ic

Y'know, I've recently seen on eBay a set of dip sockets with I integrated capacitors. Can't remember much about 'em but I thought they looked quite novel. They've been around for many years. But in the past, unless I was very tight on space, I've found it's much cheaper to use a normal DIP/DIL sock...
by 1024MAK
Tue Jan 16, 2018 10:47 am
Forum: hardware
Topic: BBC B Running slow
Replies: 11
Views: 452

Re: BBC B Running slow

There is also the possibility that there is a strange fault with the circuitry that selects between 2MHz and 1MHz for the CPU clock.

Do you have an oscilloscope, or are you able to borrow one?

Mark
by 1024MAK
Mon Jan 15, 2018 4:09 pm
Forum: off-topic
Topic: How many people found computer self-assembly annoying?
Replies: 10
Views: 336

Re: How many people found computer self-assembly annoying?

I think there are a number of things to consider here. Speaking from a perspective of being in the U.K., here are my thoughts. It could well be a different story elsewhere in the world. The computer kits were initially mainly aimed at the electronic hobbyists. Various electronics and radio enthusias...
by 1024MAK
Sun Jan 14, 2018 8:26 pm
Forum: hardware
Topic: Which replacement parts are available new?
Replies: 5
Views: 267

Re: Which replacement parts are available new?

6522 CMOS versions are indeed still being manufactured. As are various Z80 support chips. It's highly unlikely that any of the older display controller, sound chips or floppy disk controller chips are still being made. As there is significant no market for them. Most 74 series logic is still availab...
by 1024MAK
Fri Jan 12, 2018 2:11 pm
Forum: off-topic
Topic: Decoupling capacitor for ic
Replies: 11
Views: 295

Re: Decoupling capacitor for ic

There is lots of information on decoupling capacitors in this thread and further on, here . In general, a 100nF capacitor is used. But the value is not critical in most cases. So a 47nF or 220nF capacitor may well be okay. Manufacturers can sometimes use smaller values, as they can either use wider ...
by 1024MAK
Fri Jan 12, 2018 12:58 am
Forum: off-topic
Topic: Internet of Strings
Replies: 8
Views: 277

Re: Internet of Strings

It's amazing what types of electrical signal you can actually send over a relatively short section of poor quality cable... (and for AC communication signals, a wet salty "conductor" for 2 metres is equivalent to a "poor quality cable"). It's been known for a weak, but usable sig...
by 1024MAK
Thu Jan 11, 2018 9:46 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

On the Friday , numbers gradually fall during the afternoon. Leaving very diminished numbers after 16:30. Mark From the intro text, on Friday , we have the room from 5pm. Sunday, people start to drift away from about lunch time. Sorry, brain fart :oops: #-o [-X :lol: I was indeed thinking of Sunday...
by 1024MAK
Thu Jan 11, 2018 7:14 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

On the Friday, numbers gradually fall during the afternoon. Leaving very diminished numbers after 16:30.

Mark
by 1024MAK
Wed Jan 10, 2018 10:56 pm
Forum: upcoming and recent events & exhibitions
Topic: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*
Replies: 101
Views: 3624

Re: ABug NORTH User Group meeting | 19-21 JAN 2018 | MANCHESTER *BOOKING INFO*

I once came across a 8 bit computer where someone had glued a broken connector back on :shock:. Never mind about these bits of broken and unjointed metal pins... Unsurprisingly, anything plugged into said connector did not work :lol: As the connector was obsolete, I had to get a spare from a shop th...
by 1024MAK
Wed Jan 10, 2018 5:03 pm
Forum: hardware
Topic: Electron cassette counter revolution rate
Replies: 26
Views: 555

Re: Electron cassette counter revolution rate

Not with the same motor as driving the capstan as there is no single gear ratio between the captan and the take-up spool that would work, hence the slipping clutch. I guess so. Though I think only very early decks relied on a single motor. I came to the party rather later. If tape recorders/players...
by 1024MAK
Wed Jan 10, 2018 1:42 pm
Forum: hardware
Topic: Electron cassette counter revolution rate
Replies: 26
Views: 555

Re: Electron cassette counter revolution rate

the missing piece of the puzzle is that the take up spool has a clutch, often comprising a spring and a piece of felt, that enables it to slow down as the circumference of the tape wound into that spool becomes greater I thought cheap decks just used a motor with low enough torque not to stretch th...
by 1024MAK
Sun Jan 07, 2018 3:49 pm
Forum: hardware
Topic: Broken Beeb - strange memory issue, what to try next?
Replies: 12
Views: 554

Re: Broken Beeb - strange memory issue, what to try next?

Well, there goes the Beeb's build reputation :lol:

Well done =D>

Poor connections can cause all manner of hard to trace weird and not so wonderful fault symptoms :twisted:

Mark
by 1024MAK
Sat Jan 06, 2018 6:24 pm
Forum: hardware
Topic: Floppy switch configs
Replies: 41
Views: 697

Re: Floppy switch configs

Don't enter extra spaces... and check any separators are correct.

Mark
by 1024MAK
Sat Jan 06, 2018 6:18 pm
Forum: hardware
Topic: Floppy switch configs
Replies: 41
Views: 697

Re: Floppy switch configs

Post above edited.
by 1024MAK
Sat Jan 06, 2018 6:13 pm
Forum: hardware
Topic: Floppy switch configs
Replies: 41
Views: 697

Re: Floppy switch configs

BBC BASIC, link to JGH's site

Acorn MOS versions are here ;-)

Mark
by 1024MAK
Sat Jan 06, 2018 2:47 pm
Forum: hardware
Topic: Floppy switch configs
Replies: 41
Views: 697

Re: Floppy switch configs

You may also need to install a later OS chip. If you are not able to program an EPROM or EEPROM chip, buy a ROM chip from Mark of RetroClinic. Contact him via PM (if PM's have been enabled on your account) or via his web site . If you can program chips, you need a 27128, 27C128, 27256 or 27C256 EPRO...
by 1024MAK
Sat Jan 06, 2018 2:38 pm
Forum: off-topic
Topic: CPU International Crisis - Are We All Doomed?
Replies: 16
Views: 427

Re: CPU International Crisis - Are We All Doomed?

The only long term solution that I can see, is for a different architecture. Maybe splitting different code between different CPU cores that each have their own cache and therefore run completely independently from one another. The system to copy main memory to the various cache memory would however...
by 1024MAK
Fri Jan 05, 2018 6:46 pm
Forum: off-topic
Topic: CPU International Crisis - Are We All Doomed?
Replies: 16
Views: 427

Re: CPU International Crisis - Are We All Doomed?

It's simple. Just dedicate web browsing to a computer that has absolutely no private information on it and keep your private information on a separate system that has no internet connection :wink: Oh, and all 8 bit, and a lot of older 16 bit/32 bit systems have no, little or ineffective protection t...
by 1024MAK
Fri Jan 05, 2018 1:34 am
Forum: other vintage computer hardware, software and games
Topic: Early 70s Calculators
Replies: 43
Views: 2426

Re: Early 70s Calculators

fordp wrote:I had a Fx-451 at sixth form. Very good except the Flexi to the fold out keyboard breaks after a while.

Yeah, as soon as I noticed signs of cracks appearing, I stopped folding it. It has laid open and flat ever since.

Mark

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