Search found 7510 matches

by 1024MAK
Mon Jul 16, 2018 3:10 pm
Forum: hardware
Topic: Electron +Plus 1 + AP5 + MMFS question(s)
Replies: 8
Views: 169

Re: Electron +Plus 1 + AP5 + MMFS question(s)

Information on the ROM and the ROM socket inside the Plus 1 here.

Mark
by 1024MAK
Mon Jul 16, 2018 2:54 pm
Forum: hardware
Topic: 2nd User port for Beeb?
Replies: 96
Views: 6158

Re: 2nd User port for Beeb?

It's possible to use a 74LS138 (or a 74HCT138) in place of the 74LS42 in position IC4, but the pin-outs are different.

Mark
by 1024MAK
Mon Jul 16, 2018 11:54 am
Forum: hardware
Topic: 2nd User port for Beeb?
Replies: 96
Views: 6158

Re: 2nd User port for Beeb?

Yes you can connect multiple devices on the 1MHz bus. Each device must use a different address (or address range if more than one address required per device). Only the last device should have line terminating resistors fitted. The length of the total length of ribbon cable between the 1MHz connecto...
by 1024MAK
Mon Jul 16, 2018 7:33 am
Forum: hardware
Topic: I2C 4 U
Replies: 160
Views: 11964

Re: I2C 4 U

I have seen I2C RTC modules on eBay based on these: Mark
by 1024MAK
Mon Jul 16, 2018 7:07 am
Forum: hardware
Topic: Electron RGB to VGI
Replies: 6
Views: 169

Re: Electron RGB to VGI

The RGB DIN connector is the same on both BBC B/BBC Master and Electron machines. However, the Electrons with earlier issue PCBs don't produce such a bright picture compared to the Beebs and the later Electron machines.

Mark
by 1024MAK
Mon Jul 16, 2018 7:03 am
Forum: hardware
Topic: Need help figuring out how to fix a couple of Beeb PSUs
Replies: 21
Views: 383

Re: Need help figuring out how to fix a couple of Beeb PSUs

GadgetUK164 wrote:
Sun Jul 15, 2018 8:23 pm
Do you happen to have the secondary side of that diagram? Just for future reference!
See the text in the post of mine that you quoted! I have not finished it yet.

Mark
by 1024MAK
Mon Jul 16, 2018 6:59 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 32
Views: 442

Re: BeebSCSI 7_7

Just to add to the confusion, the normal description in the U.K., is that for the normal dual pin IDC connectors, the PCB mounting part is the male plug. The connector that fits the male plugs, that attach to ribbon cable are line sockets. I am not sure that is right... Isn't a PCB box header a rec...
by 1024MAK
Sun Jul 15, 2018 7:04 pm
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 32
Views: 442

Re: BeebSCSI 7_7

There's really only one type of cable connector; so it's just the type of socket on the BeebSCSI that can be varied. Sounds like you have a plan now though :) Just to add to the confusion, the normal description in the U.K., is that for the normal dual pin IDC connectors, the PCB mounting part is t...
by 1024MAK
Sat Jul 14, 2018 6:11 pm
Forum: hardware
Topic: Need help figuring out how to fix a couple of Beeb PSUs
Replies: 21
Views: 383

Re: Need help figuring out how to fix a couple of Beeb PSUs

i am a old men pc's are to moderne for me :) i can only work with paper , pencile and so on :shock: i even have plastic things with symbols #-o to draw :) Yeah, but I often work with paper and pen or pencil. It's only when I intend to publish or make a PCB board that I go to the effort of using a s...
by 1024MAK
Sat Jul 14, 2018 5:16 pm
Forum: acorn atom
Topic: new to atom: ram rom mmc joystick
Replies: 18
Views: 290

Re: new to atom: ram rom mmc joystick

Phill (Prime) is a regular here, so PM him. Alternatively he is on Facebook.

Mark
by 1024MAK
Sat Jul 14, 2018 5:10 pm
Forum: hardware
Topic: BBC Master weirdness
Replies: 2
Views: 181

Re: BBC Master weirdness

AFAIK, all 3 1 / 2 " drives use an optical sensor or microswitch to sense track zero. And I believe nearly all 5 1 / 4 " drives do the same. For most drives, there is however no sensor to detect the last track (40 or 80). So if the system is trying to step beyond track 41 to 42, or 81 to 85 (depends...
by 1024MAK
Sat Jul 14, 2018 6:55 am
Forum: hardware
Topic: Electron +Plus 1 + AP5 + MMFS question(s)
Replies: 8
Views: 169

Re: Electron +Plus 1 + AP5 + MMFS question(s)

It's well worth while reading the Acorn Electron Expansion Application Note . Especially the bit about using ROMs. The Plus 1 ROM is ROM 12 (decimal). Note that the ROM socket on the Plus 1 PCB is not wired up so that a standard EPROM can be used. An alteration is needed if you want to fit a device ...
by 1024MAK
Sat Jul 14, 2018 6:30 am
Forum: hardware
Topic: Need help figuring out how to fix a couple of Beeb PSUs
Replies: 21
Views: 383

Re: Need help figuring out how to fix a couple of Beeb PSUs

This one: https://stardot.org.uk/forums/download/file.php?id=24205&mode=view :?: That's something I doodled. In the service manual there is a schematic diagram of the Beeb PSU. But there are some differences to the actual real life PSUs. Hence why I reverse engineered the important primary side. I h...
by 1024MAK
Fri Jul 13, 2018 11:09 am
Forum: hardware
Topic: Electron overheating video
Replies: 24
Views: 384

Re: Electron overheating video

Or use a Beeb / Master etc...

Mark
by 1024MAK
Fri Jul 13, 2018 11:07 am
Forum: hardware
Topic: FreeFi-232 v2
Replies: 54
Views: 1338

Re: FreeFi-232 v2

If the software can individually control the spare RS232 outputs (DCD, RING etc), they can be used as status outputs if connected to a LED via a current limiting resistor. Gotta have some Blinkenlights =D>

Mark
by 1024MAK
Fri Jul 13, 2018 10:52 am
Forum: hardware
Topic: Electron overheating video
Replies: 24
Views: 384

Re: Electron overheating video

And a Rigol 1102E. Set up the 'scope on the composite output (monochrome mode) on a working Elk with some chunky graphics showing on screen. E.g. Coloured vertical bars. So that you can actually see the diffent voltage levels for the differently coloured bars on the 'scope. If available, set the tr...
by 1024MAK
Fri Jul 13, 2018 6:51 am
Forum: hardware
Topic: Electron overheating video
Replies: 24
Views: 384

Re: Electron overheating video

In the event of fire and/or smoke, call BeebMaster, I mean, in the event that you don't have any 'electronic' freezer spray, if you have a can of air, aka 'air duster', turn the can upside down and spay this on the chip you suspect. Failing that, put the whole naked board in the air path of a powerf...
by 1024MAK
Wed Jul 11, 2018 9:29 pm
Forum: hardware
Topic: Music 500 mod
Replies: 4
Views: 100

Re: Music 500 mod

Also, where exactly were you measuring from and to? And I trust that the power was disconnected and the 1MHz bus connector was not connected at the time.

Mark
by 1024MAK
Wed Jul 11, 2018 12:05 pm
Forum: introduce yourself
Topic: Just saying Hi
Replies: 11
Views: 231

Re: Just saying Hi

Welcome to StarDot Dave :D

Enjoy the forum :)

Mark
by 1024MAK
Wed Jul 11, 2018 11:58 am
Forum: introduce yourself
Topic: Just saying Hi
Replies: 11
Views: 231

Re: Just saying Hi

davidb wrote:
Wed Jul 11, 2018 11:46 am
Welcome! :D

And another Dave, too! Are things getting confusing for non-Daves yet? ;)
Note to self: must remember to turn off the Dave cloning machine :mrgreen:

Mark
by 1024MAK
Wed Jul 11, 2018 9:55 am
Forum: introduce yourself
Topic: Another Dutchie resurrects his A5000
Replies: 7
Views: 117

Re: Another Dutchie resurrects his A5000

Welcome on board Erik!

:D :D :D

A successful repair, great news =D>

Put yourself on the map by sticking a pin in it at this link :P
You can list your Acorn machines vitals here
You can make your confession here :mrgreen:

I hope you enjoy StarDot :D

Mark
by 1024MAK
Wed Jul 11, 2018 9:43 am
Forum: general
Topic: Today I received.....
Replies: 4684
Views: 316236

Re: Today I received.....

I've found threads on here about combining 2 x 16K images into one 32K chip, but is it also possible to combine 2x8K and 1x16K ROM images? Yes, you can combine two 8K byte ROM images into a single 16K byte EPROM. And also combine 2 x 8K ROMs with a 16K ROM. However there is a big problem with both....
by 1024MAK
Tue Jul 10, 2018 6:15 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 319

Re: Datel Modem 1979 to 1982, anyone used it?

The lines from an exchange have a current limited 50V supply. The MODEM (or telephone on the same line) has to 'load' the line (called going off-hook, same as when lifting the handset of a normal two part telephone, the line voltage then falling to between 3V and 12V approximately) then dial the num...
by 1024MAK
Tue Jul 10, 2018 4:19 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 319

Re: Datel Modem 1979 to 1982, anyone used it?

MODEMs designed only for exchange line use normally need something to simulate the exchange... For an auto dialing modem this simulation would need to be more complete but without autodial I wonder if you could get away with connecting a pair of these back to back and just provide the DC 50V. Assum...
by 1024MAK
Tue Jul 10, 2018 2:39 pm
Forum: hardware
Topic: BBC 2nd Processors: Ribbon cable connectors
Replies: 5
Views: 203

Re: BBC 2nd Processors: Ribbon cable connectors

If the existing PCB translation header and the ribbon cable at that end is okay, you could cut the ribbon cable and fit an in-line male IDC plug like this type:- IMG_7445.JPG I found this on eBay ( link ) They should also be a available from the large electronic component suppliers, but finding the ...
by 1024MAK
Tue Jul 10, 2018 12:35 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 274

Re: BASIC FOR loops

But if you want a more complex loop structure, a different form of loop rather than a FOR - NEXT loop should be used, one that has a command that can cleanly break out of a loop. And yes, many BASIC versions don't have such structures. Hence FOR - NEXT loops being pressed into service and used in un...
by 1024MAK
Tue Jul 10, 2018 12:24 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 319

Re: Datel Modem 1979 to 1982, anyone used it?

Is there any scope for you to use it, even between just two BBCs? MODEMs designed only for exchange line use normally need something to simulate the exchange... (or your own Private Branch Exchange - PBX). Although it may be possible to modify some so they can work as a private wire type (MODEM - c...
by 1024MAK
Mon Jul 09, 2018 10:42 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 319

Re: Datel Modem 1979 to 1982, anyone used it?

This machine had tape drives and HUGE 40 MB disk packs that were about the size of a washing machine." When I was at school, they organised a trip to a Westland Helicopter factory. One of the rooms had two rows of eight (I think) hard disk drives the size of washing machines. This would have been i...
by 1024MAK
Mon Jul 09, 2018 10:30 pm
Forum: other vintage computer hardware, software and games
Topic: Datel Modem 1979 to 1982, anyone used it?
Replies: 15
Views: 319

Re: Datel Modem 1979 to 1982, anyone used it?

^yeah number2, don't plug TalkTalk, PlusNet & Sky rubbish in :lol: seems PO /GPO had total control of the market pre1970, so must be why it was all their stuff plugged in Only. Unless you lived in Hull, or worked for a large company that had their own telecommunications / telephone system... Mark
by 1024MAK
Mon Jul 09, 2018 10:27 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 274

Re: BASIC FOR loops

Many BASIC implementations generate an error if there are mis-matched FOR-NEXT loops.

IMHO, that appears to be the best way of handling the problem.

Mark