Search found 7173 matches

by 1024MAK
Sat Mar 17, 2018 3:51 pm
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

Yeah, generally speaking you should set up the port for input first, then set up the port being used for output. Then you lessen the chances of two active outputs fighting one another.

Mark
by 1024MAK
Sat Mar 17, 2018 1:41 pm
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

daveejhitchins wrote:Could I use one of the control pins to latch-out from Port B and Latch-in to Port A ?
Yes, I think there is (using one control pin to indicate new data and another control pin to receive thus signal), but as I don't use this mode very often, I'll have to go and eat the datasheet...

Mark
by 1024MAK
Sat Mar 17, 2018 12:48 pm
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

6522 VIA Port A Normally (input latching disabled) reading the port results in the actual logic levels on the pins being transferred to the data bus. Port B This is similar, but in output mode, a read will return the logic level for that bit that is stored in the output latch. Not the actual logic ...
by 1024MAK
Sat Mar 17, 2018 11:58 am
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

Dave, in case I have missed it, what (if anything) is connected to the port A pins?

Mark
by 1024MAK
Sat Mar 17, 2018 11:47 am
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2574
Views: 206062

Re: Worth Taking a Look At

The first Beebs used a conventional PSU with a 50Hz mains transformer and a series voltage regulator system (often called a 'linear' power supply, but as this term is often misused and a poor description of how they work, I dislike the term). These can be identified by having no aux power connector....
by 1024MAK
Sat Mar 17, 2018 11:37 am
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

I don't know about on the Elk, but on the Beeb, the OS may change the 6522 VIA settings in some circumstances. Hence the control registers have to be set up each time the program is run. If one of the registers is not specifically set by the program, you are relying on the setting last used, or afte...
by 1024MAK
Sat Mar 17, 2018 11:24 am
Forum: hardware
Topic: BBC B Micro Power Supply - okay if run unloaded?
Replies: 17
Views: 637

Re: BBC B Micro Power Supply - okay if run unloaded?

DRAM chip failure is a very common fault in 1980s built computers. Single supply DRAM chips (as used in the Beeb) are slightly more reliable compared to triple supply DRAM (like 4116 used in other machines). But there are plenty of failures where a DRAM chip has failed on it's own. Having said that,...
by 1024MAK
Sat Mar 17, 2018 1:29 am
Forum: hardware
Topic: I've wondered this for thirty years...
Replies: 19
Views: 866

Re: I've wondered this for thirty years...

IMHO, what was the B+ should have been launched soon after DRAM prices tumbled...

Why? Because the lack of usable RAM for programs using the 20k byte graphics modes was a limitation that put the Beeb in a poor light compared to some of the competitors.

Mark
by 1024MAK
Sat Mar 17, 2018 1:24 am
Forum: hardware
Topic: BBC B Micro Power Supply - okay if run unloaded?
Replies: 17
Views: 637

Re: BBC B Micro Power Supply - okay if run unloaded?

If it was going to blow, it would only take 3 to 5 seconds... :lol: It's normally not dangerous to run a PSU off-load. But as hinted above, some of the output voltages may go outside the specifications. With the Beeb PSU, the 5V rail should be okay-ish, as that is the regulated rail. A 6V motorcycle...
by 1024MAK
Fri Mar 16, 2018 10:19 pm
Forum: hardware
Topic: Testing all 4 Ports on the New AP5
Replies: 37
Views: 684

Re: Testing all 4 Ports on the New AP5

Is it a problem wirh port A or port B?

Only there are differences between the two.

Mark
by 1024MAK
Fri Mar 16, 2018 9:40 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2574
Views: 206062

Re: Worth Taking a Look At

Nope, it went over my bid...

Reviewing the pictures and the problems listed by the seller, I can say that it has a SMPSU.

Mark
by 1024MAK
Fri Mar 16, 2018 12:38 pm
Forum: hardware
Topic: Model B Fault finding help please :)
Replies: 43
Views: 1098

Re: Model B Fault finding help please :)

On some LCD TVs you may have to go into the menus/settings and manually select PAL 50Hz mode.

I have a LCD TV that when it is set to AUTO mode, it can't lock on to the video signal :(

Mark
by 1024MAK
Fri Mar 16, 2018 12:37 am
Forum: hardware
Topic: IntegraB PAL Decoding
Replies: 41
Views: 1668

Re: PAL Decoding

I think you misunderstood what I mean... If the 74HCT244 and 74HCT174 ICs are soldered, if it is possible to feed outputs from either the printer port, or the user port to the inputs of these ICs, then do that. They will then control the PALs. As long as you know what the inputs are doing, and what ...
by 1024MAK
Thu Mar 15, 2018 11:29 pm
Forum: hardware
Topic: Model B Fault finding help please :)
Replies: 43
Views: 1098

Re: Model B Fault finding help please :)

Most Ferranti video processors (ULAs) need a heatsink. Very late versions don't need a heatsink. VTi types don't need a heatsink.

Which type is fitted?

Mark
by 1024MAK
Thu Mar 15, 2018 11:17 pm
Forum: hardware
Topic: IntegraB PAL Decoding
Replies: 41
Views: 1668

Re: PAL Decoding

If you can workout how to feed the PAL inputs (directly or indirectly via other chips), then it's not hard to use the printer and user ports on a Beeb to step through each combination of logic inputs while monitoring the outputs. From this, it is possible to work out the internal logic. This applies...
by 1024MAK
Thu Mar 15, 2018 8:32 pm
Forum: other vintage computer hardware, software and games
Topic: No more leaded solder
Replies: 47
Views: 1384

Re: No more leaded solder

Don't forget to only use water supplied via lead pipe work :lol: Now you mention it, pipes were soldered with lead-based solder too. Also, there was a segment of lead pipe to the wash basin upstairs until my parents had the bathroom re-done. That's probably OK; it's not as though we brushed our tee...
by 1024MAK
Wed Mar 14, 2018 10:25 pm
Forum: hardware
Topic: Printerface 5
Replies: 4
Views: 292

Re: Printerface 5

That would be the Alphacom 32 Printer then :wink:

Mark
by 1024MAK
Wed Mar 14, 2018 10:16 pm
Forum: other vintage computer hardware, software and games
Topic: No more leaded solder
Replies: 47
Views: 1384

Re: No more leaded solder

I intend to keep using lead for hand-soldering. I gather leaded solder is still mandated for various military applications in the USA, so it's going to continue being available for a while. I don't personally do much soldering, but it's pretty clear I urgently need to pick up a reel of thin stuff t...
by 1024MAK
Wed Mar 14, 2018 10:06 pm
Forum: general
Topic: Maplin Electronics in administration
Replies: 79
Views: 3196

Re: Maplin Electronics in administration

I went in one of the Bristol branches this week and bought some items. It appears the signage in the stores is not very good. I checked some prices on the web site. Example, an MB7 project box. On the web site it was shown as £4.65. In store it was £9 something. But IIRC the sale sign showed only a ...
by 1024MAK
Wed Mar 14, 2018 4:18 pm
Forum: other vintage computer hardware, software and games
Topic: No more leaded solder
Replies: 47
Views: 1384

Re: No more leaded solder

For making new add-ons, how bad is lead free? It is strongly recommended that you use different soldering iron bits (or separate irons), and different tip cleaners. So that the lead based solder does not contaminate the lead free solder alloy. It also requires the component legs/pins and the board ...
by 1024MAK
Wed Mar 14, 2018 2:59 pm
Forum: hardware
Topic: Model B Fault finding help please :)
Replies: 43
Views: 1098

Re: Model B Fault finding help please :)

With the Beeb, the CPU has to run the code from the ROM in order to correctly set up the CRTC chip. Now, the code in the ROM is the Acorn OS. This was written assuming that the RAM between 0x0000 and 0x3FFF is fully functional. If the RAM is faulty (in any significant way), the CPU will be unable to...
by 1024MAK
Wed Mar 14, 2018 12:09 am
Forum: archive submissions
Topic: Unidentified BBC B service Manual Extract
Replies: 7
Views: 366

Re: Unidentified BBC B service Manual Extract

marcusjambler wrote::D Its been sat under my bed :roll:

You haven't been sleeping on it for too long have you? :lol:

Mark
by 1024MAK
Wed Mar 14, 2018 12:07 am
Forum: hardware
Topic: Model B Fault finding help please :)
Replies: 43
Views: 1098

Re: Model B Fault finding help please :)

Hi Gavin

Read this post. It gives details of how the memory in a Beeb works, more details on extra tests you can do, including some BASIC programs.

See how you get on, and shout out if/when you need more help.

Mark
by 1024MAK
Tue Mar 13, 2018 12:30 am
Forum: wanted
Topic: WTD: NTSC Compatible TV
Replies: 8
Views: 329

Re: WTD: NTSC Compatible TV

That's a shame, as although European TVs are usually able to display NTSC colour pictures via baseband/composite video, most are unable to do this via the RF 'aerial' input :(

Mark
by 1024MAK
Mon Mar 12, 2018 11:34 pm
Forum: general
Topic: Maplin Electronics in administration
Replies: 79
Views: 3196

Re: Maplin Electronics in administration

As to Focus, where I live, this was (at the time) the best DIY store for the items that I was interested in. It was cheaper than Homebase (who had the highest prices and were more interested in selling homeware stuff than DIY stuff), and cheaper than B&Q. At one time, we had three DIY stores wit...
by 1024MAK
Mon Mar 12, 2018 11:13 pm
Forum: general
Topic: Maplin Electronics in administration
Replies: 79
Views: 3196

Re: Maplin Electronics in administration

To be fair, some plug-in SMPSU from Maplin that I have bought in the past have been good quality. Mind, they were not the super cheap type.

I have never bought a USB PSU from Maplin.

Mark
by 1024MAK
Mon Mar 12, 2018 1:22 am
Forum: wanted
Topic: WTD: NTSC Compatible TV
Replies: 8
Views: 329

Re: WTD: NTSC Compatible TV

I don't have a NES, so forgive me if this is unhelpful.

What video outputs does a NTSC NES actually have? I'm guessing just RF and monochrome baseband/composite video...?

Mark
by 1024MAK
Mon Mar 12, 2018 1:18 am
Forum: archive submissions
Topic: Cascade 50 - Electron tape
Replies: 7
Views: 560

Re: Cascade 50 - Electron tape

I haven't checked, but I would guess most (if not all) of the 50 games on this tape are exactly the same as on the beeb tape. :-k Who would like to do the honours and check them all? :D http://bbcmicro.co.uk/index.php?rt_R=&search=Cascade+Cassette+50&on_T=on&on_Y=on&on_P=on&on_A...
by 1024MAK
Mon Mar 12, 2018 1:15 am
Forum: software & utilities for the pc, mac or unix
Topic: iOS edition of BBC BASIC announced
Replies: 38
Views: 1383

Re: iOS edition of BBC BASIC announced

Ahh, that explains why we were talking at cross purposes...

I was assuming that at some stage you were going to release it as an app on the App Store.

Please do carry on and sorry for the distraction :oops:

Mark
by 1024MAK
Sun Mar 11, 2018 10:45 pm
Forum: archive submissions
Topic: Cascade 50 - Electron tape
Replies: 7
Views: 560

Re: Cascade 50 - Electron tape

Is this as bad as the other Casade 50 tapes that were a available for other machines?

Mark