Search found 8163 matches

by 1024MAK
Mon Jan 21, 2019 3:04 pm
Forum: hardware
Topic: A bit of fun: Which version of BBC Micro is the best?
Replies: 20
Views: 328

Re: A bit of fun: Which version of BBC Micro is the best?

Not sure if it falls into your "serious use" Mark, but some people like to tinker with electronics, which the Beeb (and Master) are especially good for. So, my taxonomy is something like this: there are collectors, gamers, users, fixers, builders, writers. (And every one of us is a bit of a mix.) Y...
by 1024MAK
Sun Jan 20, 2019 11:41 pm
Forum: hardware
Topic: A bit of fun: Which version of BBC Micro is the best?
Replies: 20
Views: 328

Re: A bit of fun: Which version of BBC Micro is the best?

All of the answers above are by sad deluded people who hang about on a forum about 1980s 8 bit computers far too much, or worse, who also go to meet-ups and play with these computers. Hence they have all missed the point... Which is, what do you want to do with it? Possible answers include (but are ...
by 1024MAK
Sun Jan 20, 2019 9:40 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 26
Views: 526

Re: New ROM / RAM Expansion Board for BBC B

Well of course 27128 and 27256 EPROMs will work, but the more modern CMOS versions (27C128 and 27C256) are lower power, which means less additional heat.

As a well known TV commercial tag line goes, every little helps :wink:

Mark
by 1024MAK
Sun Jan 20, 2019 5:26 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 26
Views: 526

Re: New ROM / RAM Expansion Board for BBC B

Board layout progressing well Looking great Ken =D> I'm wondering if it will work with a 65C02 to mitigate some of the extra power consumption Marcus Speaking of which, are you intending to use low power CMOS versions of the glue logic, such as 74HCTxxx chips? And also are you going to recommend us...
by 1024MAK
Sun Jan 20, 2019 10:24 am
Forum: hardware
Topic: Retro Hardware in FPGA's
Replies: 7
Views: 238

Re: Retro Hardware in FPGA's

Stepping back slightly from programmable logic, keep in mind that with 74xxyyy logic (and other logic ranges/chips), as well as microprocessors and support chips, designers often took liberties with proper design rules. Examples: various ULA designs including the Sinclair ZX Spectrum ULA, Acorn with...
by 1024MAK
Sat Jan 19, 2019 8:37 pm
Forum: hardware
Topic: BBC Micro B - SCART INPUT VIA VCR
Replies: 7
Views: 215

Re: BBC Micro B - SCART INPUT VIA VCR

Have you tested your Beeb on another known working colour TV? That is, do we know that the Beeb is actually working okay and producing a colour output on the RF/UHF output?

Mark
by 1024MAK
Sat Jan 19, 2019 8:35 pm
Forum: hardware
Topic: BBC Micro B - SCART INPUT VIA VCR
Replies: 7
Views: 215

Re: BBC Micro B - SCART INPUT VIA VCR

Most VCR’s if they have connections to the RGB pins on a SCART connector, just loop it through to another SCART connector (if fitted). Most are capable of taking a composite video signal and producing a RF/UHF output via their internal modulator (which may well be a better quality unit than the modu...
by 1024MAK
Sat Jan 19, 2019 11:25 am
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD
Replies: 120
Views: 4357

Re: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD

Some random photos for today... 6CAC0A45-3DA3-438D-8CFF-68ECB77522E3.jpeg 88BD6480-847B-408A-9CAA-D0D3CA0B0C54.jpeg 390CF5C9-00E5-4DF5-A46D-7569C4AB3B50.jpeg BFBF1973-0B38-409E-973D-D147F64497B7.jpeg FC5AB555-326A-49AF-A249-257DDEDAB50C.jpeg 4C0CA012-C8B1-46EF-AAE7-EE30AEC034E3.jpeg DEC5A0D6-6CA0-42...
by 1024MAK
Sat Jan 19, 2019 9:41 am
Forum: acorn atom and system
Topic: Acorn 6502 revival
Replies: 11
Views: 314

Re: Acorn 6502 revival

Thanks Kazzie, really appreciated and definitively I will use it. V0_5.JPG Good progress. Keep this in mind when attaching images: the forum software compresses and size reduces image files. So for schematics or other items where fine details are needed, please also attach the file as a zip. Mark
by 1024MAK
Thu Jan 17, 2019 2:52 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

Incidentally, you should see the total lash-up I have on my desk... this'll make you laugh! Who said you shouldn't muck about with CRTs outside their cases? :lol: Nice lash-up 8) But I think you are missing a vital item. Where is the cup of tea / soft drink? :lol: Only people scared due to the inte...
by 1024MAK
Thu Jan 17, 2019 2:14 pm
Forum: software
Topic: The Time Machine
Replies: 8
Views: 258

Re: The Time Machine

Moderators note: some posts moved from a deleted thread originally posted in the 8 bit section.

Mark
by 1024MAK
Wed Jan 16, 2019 1:28 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

In most CRT displays, the drive to both the horizontal (line) and the vertical (field) stages are generated by free running sawtooth oscillators that are synchronised by the incoming synchronisation signal(s). Of course they have very different time periods, hence use different designs of circuit. D...
by 1024MAK
Wed Jan 16, 2019 8:03 am
Forum: hardware
Topic: Romcs* observations
Replies: 5
Views: 181

Re: Romcs* observations

Not specific to Arcs, but in general, in normal use, it’s normal with ROM/EPROM/EEPROM chips to enable them as soon as possible via their chip enable/chip select pins. In most systems the ROM CS will be active anytime that the address bus holds an address pointing to a ROM address area. This is due ...
by 1024MAK
Wed Jan 16, 2019 7:52 am
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 26
Views: 526

Re: New ROM / RAM Expansion Board for BBC B

Nice 8)

I would be interested in a board and a kit of parts :wink: :D

Mark
by 1024MAK
Wed Jan 16, 2019 12:15 am
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

Jon, it’s the relationship between the horizontal sync pulse and the actual video data in the video signal. If the video data is being sent too soon after the horizontal sync, unless you can alter the circuit to produce a slightly earlier sync (or maybe a slightly shorter sync pulse), no messing wit...
by 1024MAK
Tue Jan 15, 2019 11:52 pm
Forum: hardware
Topic: Preemptive maintenance
Replies: 16
Views: 372

Re: Preemptive maintenance

Hi folks, my first post on what looks like a great site! Hello! Welcome to StarDot :D Why don’t you tell us a little more over in the ‪ introduce yourself ‬section? Is there anything else I should do to help prolong its life/catch any issues in advance? Aside from replacing the mains cable and plug...
by 1024MAK
Mon Jan 14, 2019 6:46 pm
Forum: hardware
Topic: BBC Model B faults
Replies: 14
Views: 503

Re: BBC Model B faults

It does look like a display system fault. Do you have anything (such as a PC with RS232 serial port or RS232 serial port to USB adapter) that can receive serial data? As you can get the BBC to redirect output text to the serial port. You can also redirect text input from the serial port. Then you ca...
by 1024MAK
Mon Jan 14, 2019 5:03 pm
Forum: hardware
Topic: BBC Master grumpy sideways RAM detection
Replies: 39
Views: 488

Re: BBC Master grumpy sideways RAM detection

Showing my hardware ignorance... Could this be because there's nothing responding to drive the data bus on that read, and so we're seeing an "echo" of what last went over it? Seems odd we've never seen this before! This “affect” is actually fairly common in microprocessor systems where part of the ...
by 1024MAK
Mon Jan 14, 2019 3:22 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD
Replies: 120
Views: 4357

Re: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD

If I am only able to come for one day which one would be recommended? If you can only make it for one day, the Saturday is the best day. Also, I have an unhappy BBC B (https://stardot.org.uk/forums/viewtopic.php?f=3&t=16195) and a Valiant Turtle without a communicator. Would it be too cheeky to bri...
by 1024MAK
Mon Jan 14, 2019 3:06 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

Returning to the first picture, there are still problems: Top line missing Half of the bottom line is missing The monitor sometimes struggles to lock onto the signal (despite me fiddling with the trimmer on the little composite board) Mark, you mentioned on your other thread that the position and s...
by 1024MAK
Mon Jan 14, 2019 1:01 am
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

I agree with Dave. The line / horizontal sync looks inverted. If you have a look at the more complex version of my sync combiner (same thread as the link I gave earlier), the two gates along with the resistors and jumper shunts / links enable you to select whether that gate inverts the input signal ...
by 1024MAK
Sun Jan 13, 2019 6:56 pm
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 94
Views: 7320

Re: New 65C02/W65C816 copro

=D>

Good to see you are still working on this 8)

Mark
by 1024MAK
Sun Jan 13, 2019 6:36 pm
Forum: hardware
Topic: BBC Master grumpy sideways RAM detection
Replies: 39
Views: 488

Re: BBC Master grumpy sideways RAM detection

You know what to do, remove bits until the symptoms change...

Mark
by 1024MAK
Sun Jan 13, 2019 4:09 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #3 : The Superbrain II board
Replies: 66
Views: 1020

Re: Superbrain #3 : The Superbrain II board

The resistors are included to make interfacing more compatible with existing equipment. Not all are needed in every application. If you stick the Hsync, Vsync and final composite video signal into a ‘scope, it should be possible to see what, if any tweaking is needed. Or it may just be the levels go...
by 1024MAK
Sun Jan 13, 2019 2:45 pm
Forum: hardware
Topic: POLL: How much Sideways RAM?
Replies: 20
Views: 483

Re: POLL: How much Sideways RAM?

Err, depends on which BBC B... I have this Ctorwy31 BBC 128K Sideways RAM fitted in the BBC B that I use most often. When I actually have batteries fitted and some ROMs loaded, it’s configured as having four of the 16k byte banks write protected, with no write protection on the remaining four 16k by...
by 1024MAK
Sat Jan 12, 2019 11:26 pm
Forum: acorn atom and system
Topic: Atom Colour Board Thread
Replies: 209
Views: 30280

Re: Atom Colour Board Thread

Gotta say I'm impressed with all-pcb, ordered these Monday 7th Jan, arrived Friday 11th Jan, including the journey from China! For some reason, I find that December 27th through to mid January are always good times for items coming from China to the U.K., with a lot of items making the journey in 7...
by 1024MAK
Sat Jan 12, 2019 11:22 am
Forum: general
Topic: Today I received.....
Replies: 4958
Views: 356268

Re: Today I received.....

The Psion clamshells are great pieces of kit. I have managed to assemble a mini collection of a 3, 3a, 3mx and 5mx along with a Siena and an Acorn Pocket Book 1. Fantastic bits of kit, that’s a great collection you have there. Haven’t used OPL in about 20yrs but remember it being my favourite progr...
by 1024MAK
Fri Jan 11, 2019 6:16 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD
Replies: 120
Views: 4357

Re: ABUG SOUTH 18 to 20 January 2019 (Hampshire) BOOKING THREAD

I’d be interested in John Waldron Intro to Risc.

So yes, please do bring it along.

Mark
by 1024MAK
Fri Jan 11, 2019 9:50 am
Forum: other vintage computer hardware, software and games
Topic: u256 DRAM chips
Replies: 2
Views: 128

Re: u256 DRAM chips

No.

After reading your previous comments, I stayed away from them...

Mark