Search found 7605 matches

by 1024MAK
Sun Aug 19, 2018 11:52 am
Forum: hardware
Topic: I2C 4 U
Replies: 200
Views: 13202

Re: I2C 4 U

Forget the tin foil. Just put up a load of shelving and line up a row of at least ten working ZX Spectrum computers per outside wall, each running Manic Miner...

The resulting RF interference will confuse the hell out of whatever equipment "they" are using :lol:

Mark
by 1024MAK
Sun Aug 19, 2018 11:07 am
Forum: off-topic
Topic: Printing a capacitor
Replies: 4
Views: 131

Re: Printing a capacitor

An ideal capacitor should never get hot. Real capacitors in low power signal paths don't get even slightly warm, let alone hot. By low power, I mean low current. Electrolytic capacitors that experience high ripple currents (smoothing in power supply sections), some output stage coupling capacitors i...
by 1024MAK
Sat Aug 18, 2018 2:17 pm
Forum: hardware
Topic: I2C 4 U
Replies: 200
Views: 13202

Re: I2C 4 U

Sooo, SPI as your next project?... :wink:

Mark
by 1024MAK
Sat Aug 18, 2018 9:07 am
Forum: other vintage computer hardware, software and games
Topic: Caution: Latest TL866A/CS firmware can brick programmer
Replies: 3
Views: 92

Re: Caution: Latest TL866A/CS firmware can brick programmer

This brings up an interesting question. Apart from buying direct from the manufacturer, how would you know which sellers are selling a genuine programmer?

And along the same lines, if you already have a programmer, is there an easy way to tell if it is a genuine one?

Mark
by 1024MAK
Sat Aug 18, 2018 7:25 am
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2670
Views: 220854

Re: Worth Taking a Look At

Spares... (mine has a damaged case :( )...
by 1024MAK
Sat Aug 18, 2018 7:23 am
Forum: for sale / freebies
Topic: Having a clear out
Replies: 65
Views: 2636

Re: Having a clear out

Regarding the Starfighter joystick- PM sent...

Mark
by 1024MAK
Sat Aug 18, 2018 6:43 am
Forum: software: other
Topic: software troubleshooter for beeb hardware SelfTestOs
Replies: 36
Views: 3129

Re: software troubleshooter for beeb hardware SelfTestOs

Hi Tricky For the BBC A and B machines, the following applies for the OS ROM socket. /CE ( /CS ) CPU address lines A14 and A15 are decoded by IC21 to map the ROM to the C000 - FFFF range. This is the primary address decoding. This signal tells the ROM chip to get the data from it's memory at the add...
by 1024MAK
Fri Aug 17, 2018 7:59 pm
Forum: hardware
Topic: Seeking repair help! *Solved*
Replies: 6
Views: 248

Re: Seeking repair help! *Solved*

Good, the only mouse to have is one that works =D>

Mark
by 1024MAK
Fri Aug 17, 2018 6:24 pm
Forum: software: other
Topic: software troubleshooter for beeb hardware SelfTestOs
Replies: 36
Views: 3129

Re: software troubleshooter for beeb hardware SelfTestOs

The Beeb's OS ROM socket uses both /CE (/CS) and /OE, with the different signals coming from separate sources. So no, I don't think it would work without problems.

Mark
by 1024MAK
Fri Aug 17, 2018 5:51 pm
Forum: hardware
Topic: Seeking repair help! *Solved*
Replies: 6
Views: 248

Re: Seeking repair help!

Stuart I think I have an AMX mouse somewhere, but it's likely in storage :( However, the principles are not too hard to understand. There are two signals for left / right, and two signals for up/down. I don't know what AMX called these signals, so I will call them X1, X2, Y1 and Y2. So when you move...
by 1024MAK
Fri Aug 17, 2018 5:41 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2670
Views: 220854

Re: Worth Taking a Look At

You took your time spotting that one :shock:
I been watching it for days... :lol:

Mark
by 1024MAK
Fri Aug 17, 2018 5:21 pm
Forum: hardware
Topic: Microcitec Cub 452 (Lack of) Display Issue
Replies: 8
Views: 161

Re: Microcitec Cub 452 (Lack of) Display Issue

I don't think using the analogue inputs would make any difference. I think this fault may be a problem with the electron beam scanning system. It looks like the horizontal scan may be partly working, but it appears to me that vertical scan is not working. Most CRT displays, when the brightness and c...
by 1024MAK
Fri Aug 17, 2018 3:33 pm
Forum: hardware
Topic: Microcitec Cub 452 (Lack of) Display Issue
Replies: 8
Views: 161

Re: Microcitec Cub 452 (Lack of) Display Issue

The other inputs are analogue red, green, blue and sync inputs (all terminated at 75 ohm). When using with a Beeb, you can ignore them. When using the DIN socket, the switch needs to be in the TTL position. I'm on a phone at the moment, so can't see the photo very well. Is it showing a bright horizo...
by 1024MAK
Fri Aug 17, 2018 4:36 am
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10916

Re: Open Source Logic Analyzer Experiments

Elminster wrote:
Thu Aug 16, 2018 9:31 pm
So /RSTA (pin 34 on 6522) goes low on power up only, and RST on pin 3 on 555 IC16 always flips on warm or cold rest. So that should be fairly easy to monitor while I poke about in other place.
Yeah.

Mark
by 1024MAK
Thu Aug 16, 2018 5:30 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10916

Re: Open Source Logic Analyzer Experiments

The NE555 reset circuitry can certainly cause "lock-ups" / "freezing". At a past ABUG, I had a machine which did this when the Beeb had been on for a while. It turned out to be a contaminated PCB in the area where the NE555 and it's timing resistor and capacitor are located. After a good clean, it n...
by 1024MAK
Thu Aug 16, 2018 4:40 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10916

Re: Open Source Logic Analyzer Experiments

The normal reset system uses a NE555 timer. This times whenever the system is powered up, or when the break ("reset") button is pressed.This reset signal resets the 6502 and also the user port 6522 and various other chips. This reset is available as inverted and non-inverted (/RST and RST). It's eas...
by 1024MAK
Thu Aug 16, 2018 2:23 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10916

Re: Open Source Logic Analyzer Experiments

If you have a known good working Beeb, try any suspect 6522 VIAs in this...

Mark
by 1024MAK
Wed Aug 15, 2018 5:04 pm
Forum: hardware
Topic: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male
Replies: 27
Views: 443

Re: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male

A couple of points:- Despite being "standard" machines, each machine is slightly different, this is partly due to parts from different manufacturers, and partly due to manufacturing tolerances on those parts. With a high speed computer bus (which is what the TUBE is), adding a cable, especially a ri...
by 1024MAK
Wed Aug 15, 2018 11:48 am
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2198

Re: Z80 Protocol Decoder

Wow, some deep diving into the inner workings of the Z80 CPU going on here 8)

Mark
by 1024MAK
Wed Aug 15, 2018 9:49 am
Forum: hardware
Topic: Rrad only 8271!
Replies: 6
Views: 206

Re: Rrad only 8271!

Rrad only 8271!
:shock:
Is this for radioactive software? :lol:

Yes, older floppy drive system circuitry will use 150 ohm resistors. Keep in mind that up to four drives/devices are permitted on a floppy drive bus of this type (but Acorn systems only actually support two actual drives).

Mark
by 1024MAK
Tue Aug 14, 2018 9:55 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10916

Re: Open Source Logic Analyzer Experiments

If the 6845 is working (needed to refresh the DRAM), a video fault like you describe should not affect the CPU side of the machine. Most likely two separate faults. Using the serial port to control the machine is rather fun :D When I first did this, it took me a couple of attempts to persuade it to ...
by 1024MAK
Tue Aug 14, 2018 9:46 pm
Forum: off-topic
Topic: Juice 5000mA Power bank - Aldi
Replies: 4
Views: 213

Re: Juice 5000mA Power bank - Aldi

I think I have caught a cross-virus, a cross between a Big Clive bug and a Dave Hitchins bug :shock: Last week, I found myself in B&M buying a LED worklight, as featured on the Big Clive YouTube channel, plus various solar lights. Then today, I found myself in Aldi buying a Juice power bank... Befor...
by 1024MAK
Tue Aug 14, 2018 7:48 pm
Forum: software: new games
Topic: New adventure - Send in the Clones
Replies: 6
Views: 326

Re: New adventure - Send in the Clones

Lardo Boffin wrote:
Tue Aug 14, 2018 7:03 pm
I see that this has been downloaded a few times now. Anyone made any progress?
Admissions to the local mental help clinics have apparently gone up...
by 1024MAK
Tue Aug 14, 2018 6:50 pm
Forum: hardware
Topic: Z80 Tube Speed
Replies: 2
Views: 103

Re: Z80 Tube Speed

The Acorn Z80 runs at 6MHz.
The Torch Z80 runs at 4MHz.

I think there may have been confusion over which second processor was being talked about...

Mark
by 1024MAK
Tue Aug 14, 2018 7:33 am
Forum: hardware
Topic: BBC Micro B Repair Problems
Replies: 67
Views: 754

Re: BBC Micro B Repair Problems

I wonder if a previous owner got a bit too aggressive with an upgrade/expansion, or when working on the board.
Resistors don't normally cause problems in Beebs, let alone break like you have described...

Mark
by 1024MAK
Mon Aug 13, 2018 10:52 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2198

Re: Z80 Protocol Decoder

Interesting idea Tony 8)

Mark
by 1024MAK
Mon Aug 13, 2018 10:29 am
Forum: hardware
Topic: BBC Micro B Repair Problems
Replies: 67
Views: 754

Re: BBC Micro B Repair Problems

Good progress =D>

Well done :D

Mark
by 1024MAK
Sun Aug 12, 2018 10:06 pm
Forum: hardware
Topic: Quick measurement
Replies: 28
Views: 381

Re: Quick measurement

Rockwell R6522 Port B.png
Rockwell R6522 Port B
G65SC22 Port B.png
G65SC22 Port B
Mark
by 1024MAK
Sun Aug 12, 2018 9:42 pm
Forum: hardware
Topic: Quick measurement
Replies: 28
Views: 381

Re: Quick measurement

Yeah, it's a CMOS type. Datasheet available from here :wink:

Mark
by 1024MAK
Sun Aug 12, 2018 9:29 pm
Forum: hardware
Topic: Quick measurement
Replies: 28
Views: 381

Re: Quick measurement

Ok, thanks Mark. Maybe you’ve previously robbed the 6522 from that Master for another fix because it’s almost as if it doesn’t have one fitted! 😜 Hah ha! You should know that pinching bits from a Master 128 is most likely too much like hard work, as in most Masters, everything except the ROMs are s...