Search found 7257 matches

by 1024MAK
Mon May 21, 2018 7:36 pm
Forum: hardware
Topic: Disc rot on 5 1/2” disc
Replies: 9
Views: 195

Re: Disc rot on 5 1/2” disc

<in a wonderful world where new disks are readily available> Discard any jackets that are affected / have the rot. Carefully clean any affected disks. I heard that plain soap helps, but not tried this. Once the disk is clean, allow to dry. Then, once completely dry, put in new jacket. Copy data off ...
by 1024MAK
Mon May 21, 2018 12:12 pm
Forum: hardware
Topic: Disc rot on 5 1/2” disc
Replies: 9
Views: 195

Re: Disc rot on 5 1/2” disc

I strongly recommend that you remove your jacket.
by 1024MAK
Sun May 20, 2018 5:31 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2596
Views: 211114

Re: Worth Taking a Look At

VincentVega wrote:An Acorn System 1:

https://www.ebay.co.uk/itm/Expanded-Aco ... SwkLJbAXde

Well, rather a lot of non-Acorn modules, but still very interesting, I think I'll put a bid in...

Mark
by 1024MAK
Sat May 19, 2018 6:33 pm
Forum: hardware
Topic: Screaming CUB monitors
Replies: 8
Views: 240

Re: Screaming CUB monitors

The horizontal/ line transformer and / or the horizontal defection yoke coil(s) vibrate at the horizontal/ line frequency, which is just within the hearing range of non-decrepit humans... [For system I video, it's 15625Hz]. As we get all old and... our ears become less able to detect the higher &quo...
by 1024MAK
Fri May 18, 2018 10:02 pm
Forum: general
Topic: Today I received.....
Replies: 4574
Views: 301952

Re: Today I received.....

Today's and yesterday's arrivals...
IMG_7112.JPG
Beeb SCSI

IMG_7113.JPG
Beeb SCSI

IMG_7110.JPG
NodeMCU LoLin ESP8266 ESP12E WiFi module

IMG_7109.JPG
6V solar panels

IMG_7106.JPG
gigatron kit

IMG_7107.JPG
gigatron IC's

IMG_7108.JPG
gigatron PCB

Mark
by 1024MAK
Thu May 17, 2018 8:06 am
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2596
Views: 211114

Re: Worth Taking a Look At

Slo wrote:
Lardo Boffin wrote:£134 as it turns out.


:shock: For 12 pages :shock: What's in it future proof fuel formula?


:shock: £11.17p per page :?
by 1024MAK
Thu May 17, 2018 8:04 am
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

Any addresses that are below 0F hex and / or which refer to a/the 8255 (82C55) are Z80 I/O port addresses.
You are looking for the base address of the 6522 VIA in the Tube address range.

Mark
by 1024MAK
Wed May 16, 2018 9:29 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

Hi, Z80, 6522 and 8255 and the ROM are the only socketed chips on this board. Cheers :) I think, if you don't use (maybe have to disable) the Torch ROM in the Beeb, you should be able to adapt a program designed to test the user port 6522 VIA to test the 6522 VIA on the Torch board. You would have ...
by 1024MAK
Wed May 16, 2018 9:24 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

There is no single signal that goes from the Torch board to the Beeb. All communications from the Torch Z80 go via data through the 8255 and 6522 chips.

The Z80 /BUSRQ and /BUSAK system is not used.

Mark
by 1024MAK
Wed May 16, 2018 9:04 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

The link between the two is via the 6522 VIA, controlled via the Beeb's CPU, and the 8255 PIO controlled by the Z80 CPU. The two interface chips (6522 and 8255) have their 'external' I/O pins connected between them. So that the two different CPU's can pass data between themselves. Anything that prev...
by 1024MAK
Wed May 16, 2018 8:16 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

So, it looks like the Torch board is trying to do something, the Z80 CPU is trying to execute a program.

Mark
by 1024MAK
Wed May 16, 2018 3:59 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

If after cleaning the connector pins, you still have problems, then the next step is to remove and refit any/all of the socketed chips on the Torch board. Next up, using your oscilloscope, I suggest the following checks/tests on the CPU. Does the reset pin (Z80 pin 26) go from low to high at power-u...
by 1024MAK
Wed May 16, 2018 3:30 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

Bat wrote:Hi,
Would IPA and a cotton bud be suitable for cleaning?
Cheers :)

Yes if it is general grime or grease.
If the problem is oxidation on connector pins, try using an "ink" eraser. You may need to cut it up...

Mark
by 1024MAK
Wed May 16, 2018 3:11 pm
Forum: hardware
Topic: Torch Z80 Problems
Replies: 33
Views: 384

Re: Torch Z80 Problems

Hi, Guys the start of this thread is someone else, not me! I purchased my Z80 with the ROMs and the guy assures me it all works fine. I have obtained some system discs but haven't tried them as the drive does nothing. From a ROM perspective the only thing I could think of was that it may be incompa...
by 1024MAK
Mon May 14, 2018 9:59 pm
Forum: hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 60
Views: 1695

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

“I love deadlines. I love the whooshing noise they make as they go by.”
― Douglas Adams
by 1024MAK
Mon May 14, 2018 9:27 pm
Forum: hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 60
Views: 1695

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

IMG_7063.JPG
schematic

Files attached.

Thanks to czietz over at Atari-Forum for working out how to use flow control :D =D>
[Details are in this post and one a bit further down]

Mark
by 1024MAK
Mon May 14, 2018 6:09 pm
Forum: other vintage computer hardware, software and games
Topic: Some Apple II's needing TLC at Hampshire ABUG
Replies: 7
Views: 242

Re: Some Apple II's needing TLC at Hampshire ABUG

danielj wrote:The IIe PSU has a 0.47uF RIFA, and a 0.1uF too. Not sure about any of the others - I know that the US PSUs only have one X2 ...

d.

Pitch (pin spacing distance) would be helpful :wink:

Mark
by 1024MAK
Mon May 14, 2018 5:48 pm
Forum: hardware
Topic: Cheap web-modem for the beeb/master (and arc if ya like!)
Replies: 60
Views: 1695

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

It's a shame my Master Compact is lacks the serial upgrade to make use of this, but plan on building one for use with my Arc and Psion 3a. There's some discussion of implementing flow control on an Atari forum thread I found when researching a similar project: http://www.atari-forum.com/viewtopic.p...
by 1024MAK
Mon May 14, 2018 5:45 pm
Forum: off-topic
Topic: Safely working on older equipment?
Replies: 6
Views: 469

Re: Safely working on older equipment?

I noticed that someone has moved the input voltage selector from 230V to 115V! No doubt that is the cause of the failure! The effect of the input voltage selector being in the wrong position, is effectively the same as feeding it 460V AC. When the input voltage selector is in the 115V position, the...
by 1024MAK
Mon May 14, 2018 12:20 am
Forum: upcoming and recent events & exhibitions
Topic: An important message for new members about ABUG
Replies: 1
Views: 196

Re: An important message for new members about ABUG

  • Will I need ear defenders?
:lol:

Mark

(Sorry, I couldn't resist...!)
by 1024MAK
Sun May 13, 2018 10:09 pm
Forum: software: other
Topic: SN76489 best sample playback?
Replies: 44
Views: 1005

Re: SN76489 best sample playback?

My issue 3 beeb has a SN76489AN, however my issue 2 beeb has a SN76489N. I'm very surprised and confused by this info as everything I've read suggests that the SN76489 max clock is 500Khz, (whereas SN76489A is 4Mhz max) so unless the issue 2 MB has a /8 compensation for the 4Mhz sysem clock, it see...
by 1024MAK
Sun May 13, 2018 9:27 pm
Forum: off-topic
Topic: Safely working on older equipment?
Replies: 6
Views: 469

Re: Safely working on older equipment?

Assuming you are in the U.K., you will probably find that the mains plug fuse has blown as well. Whatever died, resulted in a low impedance short circuit between line (live) and neutral. MCBs can trip, as they can have a faster response time to such faults compared to a fuse. There are various diffe...
by 1024MAK
Sat May 12, 2018 4:55 pm
Forum: hardware
Topic: BBC Serial cable
Replies: 21
Views: 2175

Re: BBC Serial cable

Daniel, keep in mind that the original purpose of RS232 and related serial interfaces was to connect to modems for communication along private telecommunications 'wires'. So the relationship between CTS and RTS and the UART (or equivalent) is not as well defined as you would have believed. I've used...
by 1024MAK
Sat May 12, 2018 11:37 am
Forum: hardware
Topic: Master 65C102 Co-pro - Hi-res PCB scans
Replies: 1
Views: 150

Re: Master 65C102 Co-pro - Hi-res PCB scans

Good luck with the schematic :wink:

That will be useful :D

Mark
by 1024MAK
Sat May 12, 2018 11:33 am
Forum: software: other
Topic: SN76489 best sample playback?
Replies: 44
Views: 1005

Re: SN76489 best sample playback?

Photos from three different issue 7 Beebs:-
IMG_7050.JPG
SN76489AN in an issue 7 BBC B
IMG_7049.JPG
SN76489AN in an issue 7 BBC B
IMG_7048.JPG
SN76489AN in an issue 7 BBC B

The earliest Beeb I have is an issue 3, but that one is somewhere in storage...

Mark
by 1024MAK
Sat May 12, 2018 10:40 am
Forum: hardware
Topic: Restoring an A3000 with lots of battery damage
Replies: 8
Views: 413

Re: Restoring an A3000 with lots of battery damage

:shock: My, that machine looks like it has been through the wars! Nice work with the restoration of the PCB 8) I I couldn't get all the green/blue corrosion off everything, but it's looking a lot nicer than it did. That's verdigris. The big electrolytics on the PSU have possibly leaked; there's some...
by 1024MAK
Sat May 12, 2018 9:15 am
Forum: software: other
Topic: SN76489 best sample playback?
Replies: 44
Views: 1005

Re: SN76489 best sample playback?

There are a number of variants. This Wikipedia page explains the differences ;-)

Mark
by 1024MAK
Fri May 11, 2018 11:28 pm
Forum: hardware
Topic: bbc master 512 keyboard acting funny
Replies: 6
Views: 292

Re: bbc master 512 keyboard acting funny

The only thing i havnt said is, ages ago, one or two of the keys where not working so i sprayed the lot with electrical cleaner... I wonder if that has done something? Depends on the chemical makeup of the "electrical cleaner"... Next, have a good look at the tracks on the keyboard PCB. W...
by 1024MAK
Fri May 11, 2018 10:38 am
Forum: software: other
Topic: SN76489 best sample playback?
Replies: 44
Views: 1005

Re: SN76489 best sample playback?

I have often pondered the same question. I figured either: ⋅ The speaker cone position goes between 0 and v, instead of -v/2 and +v/2, so the average position ends up as v/2 instead of 0. ⋅ Inertia prevents the speaker cone from actually physically moving back and forth at 125kH...
by 1024MAK
Thu May 10, 2018 8:34 am
Forum: off-topic
Topic: Pimping My Desoldering Station
Replies: 9
Views: 201

Re: Pimping My Desoldering Station

vanpeebles wrote:I think they are cutting mats?

It could be an anti static workbench mat.

Mark