Search found 7169 matches

by 1024MAK
Sun Apr 22, 2018 11:49 am
Forum: hardware
Topic: Electron: no output from RGB but video and UHF out OK
Replies: 6
Views: 210

Re: Electron: no output from RGB but video and UHF out OK

Good that you have finally found the problem. And thanks for reporting back.

Well done :D

Mark
by 1024MAK
Sun Apr 22, 2018 10:35 am
Forum: hardware
Topic: Where to start resurrecting a RiscPC 700
Replies: 10
Views: 333

Re: Where to start resurrecting a RiscPC 700

It's not a good idea to try to desolder anything at this stage. The alkaline battery leakage affects the solder, making it very difficult to get it to heat up and flow. So clean the affected areas as described above. Start by a wash with white vinegar only. Then take photos of the affected areas. Th...
by 1024MAK
Sat Apr 21, 2018 5:58 pm
Forum: off-topic
Topic: Safely working on older equipment?
Replies: 1
Views: 108

Re: Safely working on older equipment?

For future reference, it's wise to either mark the board with a marker pen (showing the + and - leads), and / or take photos showing the polarity of electrolytic capacitors before replacing them. If an electrolytic capacitor is fitted with the incorrect polarity, it is very likely to go bang with th...
by 1024MAK
Sat Apr 21, 2018 3:25 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 1 to 3 June 2018 (near Camberley)
Replies: 7
Views: 159

Re: ABUG SOUTH 1 to 3 June 2018 (near Camberley)

Yes, looking at the StarDot members who have already said that they will be attending, there should be a number of people present that may have hot soldering irons at the ready :D

May
by 1024MAK
Sat Apr 21, 2018 2:32 pm
Forum: emulators
Topic: Video Timing
Replies: 11
Views: 290

Re: Video Timing

I don't think the chip manufacturer expected it to be reprogrammed dynamically!

Remember, at the time, it was designed to drive a text screen and be controlled with (the relatively) slow microprocessors of the day.

Mark
by 1024MAK
Sat Apr 21, 2018 2:16 pm
Forum: hardware
Topic: Where to start resurrecting a RiscPC 700
Replies: 10
Views: 333

Re: Where to start resurrecting a RiscPC 700

Sorry, I disagree with you Simon on the dilution of the white vinegar. It's better to use it as is. It will not damage any tracks or components any more than they already are, as it will only be on the board for a matter of minutes. It's very important that any remaining alkaline is dealt with, or i...
by 1024MAK
Fri Apr 20, 2018 9:39 pm
Forum: hardware
Topic: Printing to a Level 4 Econet Printer Server from a BBC Micro
Replies: 8
Views: 295

Re: Printing to a Level 4 Econet Printer Server from a BBC Micro

Before I discovered StarDot (read: what feels like a lifetime ago :shock: ) I had a Beeb printing via RS423 / RS232 to a Windows 95 PC. IIRC this was just a comms program on the PC that captured the ASCII text. Or I may have been running a GW BASIC program (can't actually remember). Then I just prin...
by 1024MAK
Fri Apr 20, 2018 9:25 pm
Forum: software: classic games
Topic: Commando -Elite Systems1985- Space Invasion??
Replies: 9
Views: 190

Re: Commando -Elite Systems1985- Space Invasion??

CMcDougall wrote:PS the beeb & elk versions are exactly the same(apart from loader screen is either Red or Green on some),
so just a money spinner to buy both BITD :|

Does not surprise me with Elite Systems...
by 1024MAK
Fri Apr 20, 2018 8:56 pm
Forum: hardware
Topic: ECONET WOES
Replies: 28
Views: 925

Re: ECONET WOES

Do you have a multimeter?
The bias network / terminator should define the 'static' levels on the network when no station is transmitting.

Checking the voltages may give a clue.

Mark
by 1024MAK
Fri Apr 20, 2018 3:23 pm
Forum: hardware
Topic: SWRAM protection at power down
Replies: 5
Views: 231

Re: SWRAM protection at power down

You can use a 74HCxxx gate powered from the battery supply to control the SRAM control inputs. Plus any suitable device to detect when the main +5V supply is low. This then feeds some of the 74HCxxx gate inputs. The other inputs being the normal SRAM control signals like /WR and maybe/CS. If you get...
by 1024MAK
Thu Apr 19, 2018 5:21 pm
Forum: hardware
Topic: DFS fault codes
Replies: 6
Views: 238

Re: DFS fault codes

Keep in mind that a floppy disk drive is fairly dumb. It switches the motor on/off and steps the head forward or back on in response to the control signals from the computer. Also if the drive is to write to the disk, and the write data. With double sided drives, the computer can also choose which d...
by 1024MAK
Wed Apr 18, 2018 8:45 pm
Forum: hardware
Topic: Electron: no output from RGB but video and UHF out OK
Replies: 6
Views: 210

Re: Electron: no output from RGB but video and UHF out OK

The later PCB issues have a buffer chip between the RGB outputs from the ULA and the DIN socket.

It could be this chip.

Sorry, I'm away from my Elks, so can't check to give you any further details.

Mark
by 1024MAK
Wed Apr 18, 2018 1:10 pm
Forum: hardware
Topic: Fault finding index
Replies: 96
Views: 20100

Re: Fault finding index

There is a whole thread about using EEPROMs in Acorn computers, so make some lots of time available and go and have a nice long read of this thread :wink:

Dave H. (A member on here) can supply the correct EEPROM chips for a very reasonable price.

Mark
by 1024MAK
Wed Apr 18, 2018 12:43 pm
Forum: hardware
Topic: RGB to Component Video
Replies: 5
Views: 219

Re: RGB to Component Video

A lot of the inputs on the GBS8200 board are just paralleled connections. So for example, with the multiway PCB connector (P11), the video input connections are connected to the video input connections on the 'VGA' input D-connector. You can use either to feed 15625Hz, 625 line 50Hz TV video standar...
by 1024MAK
Tue Apr 17, 2018 11:40 pm
Forum: hardware
Topic: RGB to Component Video
Replies: 5
Views: 219

Re: RGB to Component Video

That device on Amazon looks like a GBS8200

That will work with the RGB outputs from a Beeb. See this thread for details :wink:

Also have a read through this thread :wink:

Mark
by 1024MAK
Tue Apr 17, 2018 11:35 pm
Forum: software: classic games
Topic: Is there a list of games that use co-pros?
Replies: 14
Views: 505

Re: Is there a list of games that use co-pros?

I'm primarily a hardware tinkerer rather than a assembly coder (although I have written bits and pieces of machine code for both the Z80 and the 6502, and many BASIC and some other high level language programs). But my thoughts are: as the program is designed to only run on a Z80 second processor, t...
by 1024MAK
Tue Apr 17, 2018 11:22 pm
Forum: general
Topic: Today I received.....
Replies: 4538
Views: 293633

Re: Today I received.....

If you want the contents of the EPROM chip with the uncovered window not to decay, it's best to cover the window with either a paper label or black insulation tape. Yeah I noticed that. I'm guessing that whatever is/was on it wasn't that important to the previous owner Actually, wouldn't an EPROM b...
by 1024MAK
Tue Apr 17, 2018 1:08 pm
Forum: hardware
Topic: P.R.E.S. AP5 - Original and Re-Design
Replies: 279
Views: 20047

Re: P.R.E.S. AP5 - Original and Re-Design

daveejhitchins wrote:
1024MAK wrote:I'm perfectly happy to have a kit with case instead.

Kit it is . . .

Dave H :D

Mine arrived today :D
See the Today I Received thread...

Thanks Dave =D>

Mark
by 1024MAK
Tue Apr 17, 2018 1:02 pm
Forum: general
Topic: Today I received.....
Replies: 4538
Views: 293633

Re: Today I received.....

Today...
Another box of delights from Dave H :D
IMG_6811.JPG

IMG_6812.JPG
AP5 kit with nice case

Thanks Dave =D>

Mark
by 1024MAK
Mon Apr 16, 2018 11:57 pm
Forum: software: classic games
Topic: Is there a list of games that use co-pros?
Replies: 14
Views: 505

Re: Is there a list of games that use co-pros?

@ Andy - go for it :wink: Actually, thinking about it, even if the existing OS Tube routines are used, it should be possible to port many of the ZX Spectrum / Amstrad CPC / Memotech MTX games where fast graphics / lots of graphic data changes are not a requirement. So adventure games and tactical ga...
by 1024MAK
Mon Apr 16, 2018 10:12 am
Forum: hardware
Topic: IntegraB PAL Decoding
Replies: 41
Views: 1618

Re: IntegraB PAL Decoding

Well done :D =D>

Mark
by 1024MAK
Sun Apr 15, 2018 9:31 pm
Forum: hardware
Topic: ECONET WOES
Replies: 28
Views: 925

Re: ECONET WOES

by 1024MAK
Sun Apr 15, 2018 9:13 pm
Forum: hardware
Topic: AP5, Pegasus/AP3-4/EUPURS Metal Case Design
Replies: 24
Views: 1286

Re: AP5, Pegasus/AP3-4/EUPURS Metal Case Design

@Dave - blooming marvellous =D> =D> =D>

Mark
by 1024MAK
Sat Apr 14, 2018 11:00 pm
Forum: hardware
Topic: Restoring Beeb #5
Replies: 16
Views: 569

Re: Restoring Beeb #5

All the pins should be straight and true. The two eject arms/levers should sit so that the line socket can 'plug' in freely. On the line socket, none of the connector holes should be filled in or blocked. Maybe give the plug and the line socket a clean with IPA (IPA in a spray can / aerosol can is w...
by 1024MAK
Sat Apr 14, 2018 7:40 pm
Forum: hardware
Topic: Restoring Beeb #5
Replies: 16
Views: 569

Re: Restoring Beeb #5

The problem with the 1MHz port is likely to be the pins being dirty and or tarnished. Try the usual trick of plugging/unplugging lots of times... Again, the problem with the ROM that contains BASIC not being recognised is likely to be contact problems. Remove the ROM chip and if they are dirty or ta...
by 1024MAK
Sat Apr 14, 2018 12:26 pm
Forum: general
Topic: Today I received.....
Replies: 4538
Views: 293633

Re: Today I received.....

An "untested" BBC Model B Issue 2 with Sideways ROM (+RAM?) Board. Nice 8) . If you want the contents of the EPROM chip with the uncovered window not to decay, it's best to cover the window with either a paper label or black insulation tape. Also got an EEPROM programmer with it Do you me...
by 1024MAK
Sat Apr 14, 2018 10:40 am
Forum: hardware
Topic: Restoring Beeb #5
Replies: 16
Views: 569

Re: Restoring Beeb #5

KarateEd wrote:Geez, you could grow potatoes in there.

Ed......

Potatoes? That's deep enough for a whole allotment worth of vegetables :lol:

Having said that, I found actual soil and mud in one old computer once :shock:

Mark
by 1024MAK
Fri Apr 13, 2018 10:10 pm
Forum: hardware
Topic: Tv display top line problem
Replies: 12
Views: 365

Re: Tv display top line problem

I’ll take a look online but the set is from 98, so 20 years old. Richard B If it does not have on screen menus, then there may well be preset vararable resistors on the PCB to enable adjustment. But unless you are used to working inside CRT displays, I don't recommend trying to do it yourself. Oh, ...
by 1024MAK
Fri Apr 13, 2018 7:39 pm
Forum: hardware
Topic: Elk advice
Replies: 14
Views: 423

Re: Elk advice

But before you take the keyboard apart, if the operation of individual keys is erratic, operating each of the offending keys repeatedly about 50 to 100 times can help clean the contacts inside.

Mark
by 1024MAK
Fri Apr 13, 2018 7:36 pm
Forum: hardware
Topic: Tv display top line problem
Replies: 12
Views: 365

Re: Tv display top line problem

How old is the TV that you are using? Does it have an on screen menu system? If yes, it may be worthwhile searching online to see if you can find the special key sequence to get to the engineering/technician/set-up menu. This often has values that can be changed to alter the displayed image position...