Search found 7527 matches

by 1024MAK
Sun Jul 08, 2012 6:30 pm
Forum: general
Topic: Has BBC Docs disappeared?
Replies: 47
Views: 5522

Re: Has BBC Docs disappeared?

Until this week I used to use HTTrack to copy websites, but I always found it slow and inefficient, only managing a data transfer rate of about 20K/sec and only coping with one file at a time. I probably abandoned the copy after a couple of days of sluggish copying! Change the settings then! Here I...
by 1024MAK
Sun Jul 08, 2012 10:36 am
Forum: software: other
Topic: Best /most essential roms to blow onto 64k EPROMs?
Replies: 10
Views: 1406

Re: Best /most essential roms to blow onto 64k EPROMs?

As stated above, every image must start on a 16k byte (16384 byte) boundary. &0000 - first ROM image &4000 - second ROM image &8000 - third ROM image &C000 - 4th ROM image etc The above example will be the layout as seen by the programmer and the application that assembles the file. However the Beeb...
by 1024MAK
Sun Jul 08, 2012 10:17 am
Forum: hardware
Topic: Both shift keys stopped working
Replies: 35
Views: 4098

Re: Both shift keys stopped working

So if the the shift keys test okay with the BASIC test program it means it is a software / firmware issue, not a hardware fault.

Mark
by 1024MAK
Sat Jul 07, 2012 11:12 pm
Forum: hardware
Topic: Both shift keys stopped working
Replies: 35
Views: 4098

Re: Both shift keys stopped working

You say that you do not have another Master, but do you have a model A, B, or B+ ? It is possible to connect a A, B or B+ keyboard to a Master. Also both shift keys are electrically connected. But as far as I can see, have no common connection with the £ key. However it is possible that the encoder ...
by 1024MAK
Sat Jul 07, 2012 7:32 pm
Forum: hardware
Topic: Both shift keys stopped working
Replies: 35
Views: 4098

Re: Both shift keys stopped working

Weird :shock: :?
by 1024MAK
Sat Jul 07, 2012 5:48 pm
Forum: hardware
Topic: Both shift keys stopped working
Replies: 35
Views: 4098

Re: Both shift keys stopped working

Do you have any problems with any other keys (including the Control key)?
Does the Beeb start up okay?

Mark K.
by 1024MAK
Sat Jul 07, 2012 5:34 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

Assuming I am not going completely loopy, I would say that IC65 is the troublesome RAM chip in your machine.

Mark
by 1024MAK
Sat Jul 07, 2012 3:24 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

So in my case, am I right in thinking this points to IC57 before I get the hammer, chisel and soldering iron out?? :) In my above post I confused myself :oops: Jumping from watching the F1 race, entertaining my sister and her kids and thinking about this subject has overloaded me single tasking bra...
by 1024MAK
Sat Jul 07, 2012 2:24 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

Data bits - IC numbers /CAS0 /CAS1 D0= IC61 IC53 D1= IC62 IC54 D2= IC63 IC55 D3= IC64 IC56 D4= IC65 IC57 D5= IC66 IC58 D6= IC67 IC59 D7= IC68 IC60 With a model A /CAS1 controls the only 16k RAM bank, as IC61 to IC68 are not present. With a model B /CAS0 controls the lower 16k RAM bank and /CAS1 cont...
by 1024MAK
Sat Jul 07, 2012 1:33 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

Code: Select all

             76543210
16 decimal = 00010000
So still a bit D4 fault.

Mark K.
by 1024MAK
Sat Jul 07, 2012 1:18 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

Often the faults are intermittent or temperature dependent. When I say temperature dependent , I mean the components warm up over time until the temperature stabilises at its normal level. This varies between different models. But a time between 30 minutes and 2 hours is typical. As the temperature ...
by 1024MAK
Sat Jul 07, 2012 10:12 am
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

The result, 239 is a decimal number. When converted to a binary number, it has more meaning:- 239 decimal = 11101111 binary bit number 76543210 result= 11101111 So it looks like the DRAM chip in that bank that provides data bit D4 is faulty and needs to be replaced. (Data bits are normally numbered ...
by 1024MAK
Sat Jul 07, 2012 10:05 am
Forum: hardware
Topic: Display Problems
Replies: 8
Views: 3175

Re: Display Problems

Cross reference to other thread >>> http://stardot.org.uk/forums/viewtopic. ... 305#p49142
by 1024MAK
Fri Jul 06, 2012 11:36 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

16384-word X 1-bit Dynamic Random Access Memory The HM4816 is a new generation MOS dynamic RAM circuit organized as 16,384 words by 1 bit. As a state-of-the art MOS memory device, the HM4816 (16K RAM) incorporates advanced circuit techniques designed to provide wide operating margins, both internal...
by 1024MAK
Fri Jul 06, 2012 9:15 pm
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

Right - I've made all the mods (except tying CE to OE - looking at the datasheet I couldn't see how that would work) As long as your timing signals are correct, connecting the SRAM pin 24 (OE#) and pin 22 (CE#) should work okay. I have just checked the data sheet and when operating on a +5V supply,...
by 1024MAK
Fri Jul 06, 2012 9:07 pm
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

An obvious problem is that the OE signal is less than 1V pp, and it looks like a sine wave not a square wave. I've probably made a schoolboy error - I used a 4k7 resistor and a 47pF capacitor in my RC circuit. Is the resistor way too big - should I use something like 200R and a bigger cap? I think ...
by 1024MAK
Fri Jul 06, 2012 7:31 pm
Forum: hardware
Topic: Amazing Beeb Model B
Replies: 11
Views: 1576

Re: Amazing Beeb Model B

Funny, I never wanted a open top sports car.

Something to do with the lovely summer weather I think :lol:

Mark K.
by 1024MAK
Fri Jul 06, 2012 7:27 pm
Forum: hardware
Topic: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please
Replies: 62
Views: 6252

Re: Beeeeeeeeeeeeeeeeeeeeeeeee faulty beeb help please

I think it is based on checking one bank only for one type of individual bit fault. Each DRAM chip is actually a one bit by 16k memory. So to make a 16k byte memory bank you need 8 chips. Each chip being connected to a different data bit. If one chip is faulty due to a faulty data input or output ci...
by 1024MAK
Fri Jul 06, 2012 1:01 am
Forum: general
Topic: Has BBC Docs disappeared?
Replies: 47
Views: 5522

Re: Has BBC Docs disappeared?

=D> =D> =D> :D :D :D

A BIG thank you to BeebMaster and Sam 8)
by 1024MAK
Thu Jul 05, 2012 9:20 am
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

You may find these web pages useful:- http://wilsonminesco.com/6502primer/addr_decoding.html http://wilsonminesco.com/6502primer/LogicFamilies.html http://wilsonminesco.com/6502primer/ClkGen.html As you will find as you are reading them, the phase 2 clock is normally used for bus-control. But cannot...
by 1024MAK
Wed Jul 04, 2012 1:14 am
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

Timing diagrams attached for ease of reference :D
W65C02S timing S.png
W65C02S timing
W65C02S timing S.png (58.05 KiB) Viewed 1199 times
AS6C1008 SRAM Read timing S.png
AS6C1008 SRAM Read timing
AS6C1008 SRAM Read timing S.png (43.22 KiB) Viewed 1199 times
AS6C1008 SRAM Write timing S.png
AS6C1008 SRAM Write timing
AS6C1008 SRAM Write timing S.png (60.87 KiB) Viewed 1199 times
6502 timing.png
6502 timing
6502 timing.png (41.6 KiB) Viewed 1199 times
In the 6502 timing diagram, you want the SRAM to respond in the area of the vertical line marked Ref "C" (at the bottom of the image).
by 1024MAK
Tue Jul 03, 2012 8:46 pm
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

One (well two) important points that I feel need talking about. Logic levels on a data bus take time to get to a logic high and take time to get to a logic low. Even though the 2P MPU only has the 64k (of the possible 128k) SRAM on its data bus, when the MPU switched from reading to writing to the S...
by 1024MAK
Tue Jul 03, 2012 7:40 pm
Forum: general
Topic: Has BBC Docs disappeared?
Replies: 47
Views: 5522

Re: Has BBC Docs disappeared?

TopBanana wrote:You mean there's life outside of the Stardot forums ?? :shock: :shock: :lol:
"It's life, Jim, but not as we know it."
by 1024MAK
Tue Jul 03, 2012 12:20 am
Forum: hardware
Topic: Electron Second Processor project
Replies: 228
Views: 22026

Re: Electron Second Processor project

The diagrams that were attached to the earlier post do print out fairly well (having Firefox I just right clicked, saved them and then send them to my network laserJet). I course finding the bits of paper now is another matter :roll: As MartinB said, DRAM chips are correctly addressed (accessed and ...
by 1024MAK
Mon Jul 02, 2012 9:20 am
Forum: hardware
Topic: Soldering how to
Replies: 13
Views: 1431

Re: Soldering how to

Trying to repair old gear using the lead-free cr*p can be a nightmare. Maybe a silly question, but why would it be harder to repair old gear with lead free solder than new gear? Is that just because lead and lead free solder dont mix? Yep. It is not a good idea to mix them. Even small amounts of co...
by 1024MAK
Sun Jul 01, 2012 8:45 am
Forum: hardware
Topic: LTM Portable Master
Replies: 2
Views: 450

Re: LTM Portable Master

Unless there has been a physical knock, or an internal flash-over it is unlikely that the tube itself has died. When following the fault finding notes below, be very careful as CRT's and the driver and control circuitry operate at high voltages (HV or HT) and (EHT - extra-high tension). Keep one han...
by 1024MAK
Fri Jun 29, 2012 7:09 pm
Forum: for sale / freebies
Topic: Original Beebug disks
Replies: 6
Views: 1239

Re: Original Beebug disks

Yes, it is funny how some things go. I normally assume that items for sale get snapped up quick (at least often on the same day, if not within hours). Please give us some idea of the amount that you are looking for. I imagine postage for this lot is not going to be cheap either. As you may have gues...
by 1024MAK
Fri Jun 29, 2012 6:27 pm
Forum: hardware
Topic: 3.5" FDD. [SOLVED]
Replies: 12
Views: 1275

Re: 3.5" FDD

I use Sony MPF920 drives with my BBC Master (plus my other non Acorn computers). I also have a number of other non-Sony 3.5" drives, but cannot remember which I have used with my Masters. The Sony MPF920 drives are often available on eBay but as they were intended for PC's always come without an out...
by 1024MAK
Tue Jun 26, 2012 11:56 pm
Forum: hardware
Topic: PSU and over heating question
Replies: 38
Views: 2456

Re: PSU and over heating question

<snip> beeb are powered from an odd 4 plug extension adapter that takes 2 pin plugs. Aha, that be the problem then, see! :!: :!: :!: :shock: You just don't yea get the right current flow through them thar 2 pin lugs. That be the wee problem! :!: :shock: :lol: :lol: :lol: Unlike the coool Beeb you w...