Search found 7835 matches

by 1024MAK
Sat Oct 20, 2018 3:57 am
Forum: acorn atom and system
Topic: System floppy controller clone....
Replies: 2
Views: 70

Re: System floppy controller clone....

Does BeebMaster not have an enormous stockpile of Econet modules in the BeebVault? :mrgreen:

Although joking aside, yes it’s wise to have the Econet component positions on the PCB :D.

Mark
by 1024MAK
Sat Oct 20, 2018 12:22 am
Forum: other vintage computer hardware, software and games
Topic: Poxy German DRAMs!
Replies: 6
Views: 110

Re: Poxy German DRAMs!

Part 2 So ‘Boot-repair’ started to do it’s thing. I answered the questions and entered the terminal commands into a bash terminal. It downloaded some files. Spat out a warning, but finished without any errors. Time to remove the DVD and let the system try to boot from the HDD. At last, Linux booted ...
by 1024MAK
Fri Oct 19, 2018 11:38 pm
Forum: other vintage computer hardware, software and games
Topic: Poxy German DRAMs!
Replies: 6
Views: 110

Re: Poxy German DRAMs!

Not done anything with any 1980s/1990s computers for a while :-( What follows is the slightly shortened (!) version... (no, honestly...) On Tuesday evening, I let my main (Linux) PC do an update. When rebooting, I found it had a very (and nearly useless) command line interface. No, not even ‘bash’. ...
by 1024MAK
Fri Oct 19, 2018 6:47 pm
Forum: other vintage computer hardware, software and games
Topic: Poxy German DRAMs!
Replies: 6
Views: 110

Re: Poxy German DRAMs!

The data sheet that I found looks to give the access time as 200ns.

Mark
by 1024MAK
Fri Oct 19, 2018 6:38 pm
Forum: other vintage computer hardware, software and games
Topic: Poxy German DRAMs!
Replies: 6
Views: 110

Re: Poxy German DRAMs!

I don’t think I have any U256D chips. There are lots of equivalents for 4116 DRAMs though. I have bought some 16k x 4 bit chips by accident in the past when I was not paying attention :oops: I’m sure one day, I will find a use for them... Back to your problem. Is the pin-out the same? Are the U256D ...
by 1024MAK
Fri Oct 19, 2018 9:19 am
Forum: general
Topic: Were 'podules' ever considered for the BBC Micro?
Replies: 5
Views: 232

Re: Were 'podules' ever considered for the BBC Micro?

To nick a phrase from elsewhere in the computing industry, “where do you want to go today”? Or rather, which market segment do you want to sell to? What do you want a computer for? Games? Educational? Business? Scientific? Accounts? Process control? In the 1980s engineers/inventers/companies came up...
by 1024MAK
Wed Oct 17, 2018 8:34 pm
Forum: hardware
Topic: Colour link on BBC Master
Replies: 7
Views: 174

Re: Colour link on BBC Master

In simple terms, a composite signal that does not include the colour carrier (be it PAL or NTSC) is equivalent to a single colour channel of an analogue RGB signal. So for example, if you have a display device which accepts an analogue RGB input and there is an option for sync on green, you can feed...
by 1024MAK
Mon Oct 15, 2018 12:30 pm
Forum: other vintage computer hardware, software and games
Topic: SCSI2SD on the Victor 9000
Replies: 19
Views: 1261

Re: SCSI2SD on the Victor 9000

There is no quick way of reverse engineering a complex PCB. However, educated guesses and a multimeter on the resistance range can help when dealing with certain chips. Especially if the design of that part of the circuit is the same as, or similar to the chip manufacturers example or typical circui...
by 1024MAK
Mon Oct 15, 2018 7:45 am
Forum: hardware
Topic: Tatung Einstein Monitor to C64
Replies: 4
Views: 85

Re: Tatung Einstein Monitor to C64

RGB TTL (or TTL RGB) uses 5V logic level signals to communicate the eight (additive) primary colours via three circuits (three wires) plus one or two synchronisation signals and a 0V/GND connection. The BBC B, BBC Master and Acorn Electron use this system to connect to suitable Microvic Cub monitors...
by 1024MAK
Mon Oct 15, 2018 5:47 am
Forum: hardware
Topic: Tatung Einstein Monitor to C64
Replies: 4
Views: 85

Re: Tatung Einstein Monitor to C64

C64/C128 output composite video (some output what these days we call S-Video as well). So as long as the monitor has a composite input (or better yet, S-Video or equivalent inputs) it should be possible. Looking at this web page , a monochrome image looks possible. But without a signal converter cir...
by 1024MAK
Sun Oct 14, 2018 2:02 pm
Forum: software & utilities for the pc, mac or unix
Topic: Wires? Pah.....
Replies: 833
Views: 111079

Re: Wires? Pah.....

If you are getting data errors, they are much more likely with disk images rather than ROM images, simply due to the size. Most people leave unused bytes in EPROMs/EEPROMs as 0xFF. Because that is the value that a byte goes to when a EPROM or EEPROM goes to when erased. So it saves a programmer (a b...
by 1024MAK
Sun Oct 14, 2018 10:37 am
Forum: other vintage computer hardware, software and games
Topic: CRT fungus removal ("cataracts")
Replies: 23
Views: 343

Re: CRT fungus removal ("cataracts")

Two things... It’s not a very good “screen protector” if it can’t even keep mould out...! I’m disappointed that the big white power button does not light up... Mark It's the glue that goes mouldy! But you knew that . . . Dave H :D Oi! Someone’s cut a link in the chain that I was yanking! :shock: :l...
by 1024MAK
Sun Oct 14, 2018 2:07 am
Forum: other vintage computer hardware, software and games
Topic: CRT fungus removal ("cataracts")
Replies: 23
Views: 343

Re: CRT fungus removal ("cataracts")

Two things...
It’s not a very good “screen protector” if it can’t even keep mould out...!
I’m disappointed that the big white power button does not light up...

Mark
by 1024MAK
Sun Oct 14, 2018 1:58 am
Forum: hardware
Topic: BBD B+ Issues..please help
Replies: 20
Views: 535

Re: BBD B+ Issues..please help

Yes, that is the next step. Freezer spray (or an air duster spay can uses upside down)...

Mark
by 1024MAK
Fri Oct 12, 2018 4:57 pm
Forum: software: other
Topic: What will stop ADI2 accessing DFS Track 0?
Replies: 17
Views: 337

Re: What will stop ADI2 accessing DFS Track 0?

Yeah, but the system reads the disk to locate that logical position. Sector and track data is stored on the disk as part of the format. The drive is a dumb device (and on soft sectored disks) there is only a single physical index pulse and on some drives, a single “track zero” signal. All the clever...
by 1024MAK
Fri Oct 12, 2018 1:26 pm
Forum: off-topic
Topic: Convert master psu to bench psu
Replies: 37
Views: 1002

Re: Convert master psu to bench psu

And don’t forget to enjoy destroying that deathdaptor :lol:
by 1024MAK
Fri Oct 12, 2018 1:19 pm
Forum: hardware
Topic: BBC B repair help
Replies: 9
Views: 254

Re: BBC B repair help

The MODE used for start-up is determined by the keyboard links/DIP switches (as are some filing systems options). See this web page . If the “system” 6522 VIA (IC3) is not present, the OS can’t read the keyboard links/DIP switches. Yes, I know that most machines don’t have any links or DIP switches ...
by 1024MAK
Fri Oct 12, 2018 12:14 pm
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 294

Re: Master 128 SCART Fun

Elminster wrote:
Fri Oct 12, 2018 11:42 am
So the idea is that each diode drops about 0.65Vs?

Wouldnt you traditionally use a zenner to clamp the voltage instead?

Just trying to follow along.
Yes, you could use a 2.7V Zener diode. But how many of us have one spare?

Mark
by 1024MAK
Fri Oct 12, 2018 11:32 am
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 294

Re: Master 128 SCART Fun

I suggest for pin 16, to limit the voltage to between 2.4V and 2.8V, connect four 1N4148 (or equivalent) signal diodes in series between pin 16 (first diode anode connection) and a suitable 0V/GND pin (last diode cathode connection). The original resistor stays connected between the Beeb’s +5V pin a...
by 1024MAK
Fri Oct 12, 2018 9:33 am
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 294

Re: Master 128 SCART Fun

I would not worry about the input voltages from the Beeb not dropping down after the resistors. It may well be the case that the TV does not load all the inputs to 75 ohms unless it is in RGB input mode. And in any case, it’s highly unlikely that the 5V will do any harm, as (1) the current must be v...
by 1024MAK
Fri Oct 12, 2018 9:22 am
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 294

Re: Master 128 SCART Fun

This picture:
Image
Is typical of a TV in SCART composite mode, but with only a RGB signal being fed to it. The visible white elements are simply crosstalk.

Mark
by 1024MAK
Fri Oct 12, 2018 9:19 am
Forum: hardware
Topic: Master 128 SCART Fun
Replies: 17
Views: 294

Re: Master 128 SCART Fun

LG TVs (and a lot of other LCD TVs) default to composite video inputs on their SCART inputs (as is normal). Some TVs have a user manual selection control in the menus or via a remote control button. However this does not apply to all modern(-ish) TVs. For these, you have to supply the correct voltag...
by 1024MAK
Thu Oct 11, 2018 2:04 am
Forum: hardware
Topic: EEPROM - the Holy Grail of Sideways Rom?
Replies: 397
Views: 36534

Re: EEPROM - the Holy Grail of Sideways Rom?

MartinB wrote:
Wed Oct 10, 2018 10:11 pm
it would have looked like I was quoting myself!
Never stopped you before :lol:

Mark
by 1024MAK
Wed Oct 10, 2018 11:45 pm
Forum: off-topic
Topic: Where do you get your retrocomputing fix?
Replies: 31
Views: 434

Re: Where do you get your retrocomputing fix?

There is an old thread that may be relevant Additional fora for non Acorn machines? I mainly use forums and websites. Occasionally I dip my feet into Facebook groups. These are some other 8 bit and 16 bit computer forums where I am a member:- ZX80, ZX81 and clones: Sinclair ZX World forums ZX Spectr...
by 1024MAK
Wed Oct 10, 2018 1:38 pm
Forum: software: other
Topic: ADFS Deleted File Recovery - Assistance Required
Replies: 22
Views: 362

Re: ADFS Deleted File Recovery - Assistance Required

Col does say DFS in his post...
I think he intended that it may show what may be possible on ADFS...

And Colin being a lover of DFS, and, well, shall we say “not too keen” on ADFS, you would not expect him to have a ADFS tool, would you?!

Mark
by 1024MAK
Wed Oct 10, 2018 10:56 am
Forum: hardware
Topic: Master 128 LNK12
Replies: 2
Views: 90

Re: Master 128 LNK12

From the service manual: LK12 Plug, made B (East): CSYNC/Cartridge Machine Detect. Two position link. Position A - This connection to the computer CSYNC line is provided for GENLOCK purposes. Position B - Certain hardware cartridges may need to detect whether they are plugged into a Master Series co...
by 1024MAK
Wed Oct 10, 2018 10:33 am
Forum: off-topic
Topic: Where do you get your retrocomputing fix?
Replies: 31
Views: 434

Re: Where do you get your retrocomputing fix?

Ed, the image/link in your post does not work as a picture, but does work as a link.

Mark
by 1024MAK
Wed Oct 10, 2018 5:06 am
Forum: hardware
Topic: How to Health Check My BBC Master (128/512)
Replies: 27
Views: 508

Re: How to Health Check My BBC Master (128/512)

Acorn did design the Master with a rechargeable battery charging circuit. But it all went rather wrong :shock: Hence Acorn abandoning using rechargeable batteries. And then supplying the Master machines without the recharging circuitry fitted, and with alkaline battery packs. The second problem used...
by 1024MAK
Mon Oct 08, 2018 11:51 am
Forum: hardware
Topic: How to Health Check My BBC Master (128/512)
Replies: 27
Views: 508

Re: How to Health Check My BBC Master (128/512)

IC11 is the CMOS RTC chip (416818). If you can’t get to it, and if you can get to the metal pin, test on the pin header where the battery lead connects to the main board (PL8). The positive connection is the middle pin. With the machine switched on, about 4.3V to 4.7V should be present. With a worki...
by 1024MAK
Mon Oct 08, 2018 10:20 am
Forum: hardware
Topic: How to Health Check My BBC Master (128/512)
Replies: 27
Views: 508

Re: How to Health Check My BBC Master (128/512)

Unless you find a problem, the main things to test with a multimeter are: +5V DC supply within specification (red wires from the PSU to the main board) -5V DC supply within specification (purple wire from the PSU to the main board) +12V DC supply within specification (external power socket) IC11 pin...