Search found 256 matches

by mikeb
Fri Oct 23, 2020 4:07 pm
Forum: Hardware hacks and extensions
Topic: Expansion port for external ROM and /ROMDIS line
Replies: 4
Views: 232

Re: Expansion port for external ROM and /ROMDIS line

Ooh, that's me :) I certainly don't think I invented that method (it likely fell in from another interface design elsewhere) and I can't think of a good reason why tying ROMDIS low wouldn't work, if you want to shove the internal ROM aside permanently. TBH, I'm not sure why I didn't just do that mys...
by mikeb
Mon Oct 12, 2020 5:31 pm
Forum: Technical questions
Topic: Atmos, WDC65C02 and WDC65C22N and other
Replies: 8
Views: 776

Re: Atmos, WDC65C02 and WDC65C22N and other

But since my machine does not want to go further than the boot screen with the 65C02 and 65C22 fitted at the same time (why :?: ) Could be completely wrong here, but wasn't one of the changes around the 65C02 and 65C22 something to do with the IRQ line (out from VIA, in to CPU) being changed from T...
by mikeb
Sun Oct 11, 2020 6:23 pm
Forum: Technical questions
Topic: Atmos, WDC65C02 and WDC65C22N and other
Replies: 8
Views: 776

Re: Atmos, WDC65C02 and WDC65C22N and other

Another weird thing is when I launch the excellent DIAGROM (without any add-on cards): with the original VIA fitted, the "timer test" passes but when a 65C22N is inserted, timer test fails. As the code was written and tested against a 6522A (as standard) it's likely that it's missing something that...
by mikeb
Fri Oct 02, 2020 5:26 pm
Forum: Technical questions
Topic: Printer?
Replies: 8
Views: 687

Re: Printer?

IIRC the problem with modern printer with the true type fonts was that they didn't necessarily recognise ASCII codes. Oh, I'd forgotten, some printers are such a designed-down cheaped-out piece of trash that they are barely a couple of motors, a pencil and a power-supply, everything being done in s...
by mikeb
Thu Oct 01, 2020 5:30 pm
Forum: Technical questions
Topic: Printer?
Replies: 8
Views: 687

Re: Printer?

My HP 950 should have worked but I couldn't get it to print with an Oric. Might be just HP's idea of Centronics is still different to others! At one point, we had an HP82906A dot-matrix with Centronics connected to Oric, but initially it didn't want to work. Details are getting fuzzy now, but it wa...
by mikeb
Thu Oct 01, 2020 5:21 pm
Forum: Technical questions
Topic: Last ATMOS finally repaired !
Replies: 5
Views: 200

Re: Last ATMOS finally repaired !

- The ATMOS booted normally with its original ULA, but the "checker board pattern" had some artifacts. The boot screen is normal with the actual ULA. Does it also mean the original ULA chip is damaged ? The checkerboard pattern is an illusion created by the particular brand of DRAM chips you use. T...
by mikeb
Thu Oct 01, 2020 5:18 pm
Forum: Technical questions
Topic: Last ATMOS finally repaired !
Replies: 5
Views: 200

Re: Last ATMOS finally repaired !

- One of the two AY-3-8912 PSG I tried only produced PING and ZAP sounds. SHOOT and EXPLODE had no effect. Does it mean the chip is defective or damaged ? PING and ZAP use the normal three channel generator, while SHOOT and EXPLODE are using the noise generator, so maybe something happened there. I...
by mikeb
Sun Sep 27, 2020 6:21 pm
Forum: Operating systems, utilities and other serious software
Topic: Oric tape loading
Replies: 7
Views: 733

Re: Oric tape loading

Is there room to try an alternative loader without messing up the rest of the ROM? If you mean the 16K Oric BASIC ROM, then I don't think there's any room to speak of AT ALL. It's full. Any extensions and bug fixes would require everything else be squished up a little tighter, which is probably one...
by mikeb
Wed Sep 23, 2020 4:17 pm
Forum: Tape and floppy disk converters
Topic: Maxduino now plays Oric native tap files
Replies: 26
Views: 1230

Re: Maxduino now plays Oric native tap files

Never understood why this header pins for arduino mini are not soldered by default :roll: Cost. In many applications they won't be needed. It costs nothing (well ... a tiny amount) to add the appropriate holes/tracks/silk-screen to bring the pads to somewhere a connector *could* go, at design time,...
by mikeb
Sun Sep 13, 2020 5:33 pm
Forum: General Discussion
Topic: Oric cleaning :)
Replies: 8
Views: 1326

Re: Oric cleaning :)

clean the keyboard membrane Unless it's been used by someone playing games too long, in which case the cursor keys may have collapsed (true: The rubber cups fatigued on original Oric keyboard here from this!) one is limited to blowing air over the exposed spring mechanisms after the key caps are re...
by mikeb
Wed Sep 09, 2020 6:21 pm
Forum: Technical questions
Topic: Microdisc Service Manual
Replies: 17
Views: 1647

Re: Microdisc Service Manual

I posted you the voltages I was getting in a PM but I think you may have missed it. It was just under 12V which I thought might be near enough - but maybe it is a bit low? No PM alert showing, so unless you mean a while ago? But the 12V rail is usually not critical (5V is!) and often sags when moto...
by mikeb
Wed Sep 09, 2020 5:49 pm
Forum: Technical questions
Topic: Atmos excessive buzzing from speaker
Replies: 8
Views: 1039

Re: Atmos excessive buzzing from speaker

Purring is a happy Oric noise. It's a good sign! When you power on the Oric, while the memory test is happening you get a more frantic whirring noise, then a "kerplink!" (part of which I think is the cassette relay open-closing during setup of the VIA chip), just as the screen wipes to grey and goes...
by mikeb
Tue Sep 08, 2020 5:41 pm
Forum: Hardware hacks and extensions
Topic: TSN 1-2450A instead of LM7905
Replies: 20
Views: 2203

Re: TSN 1-2450A instead of LM7905

It says startup time is 15ms at nominal vIn with constant resistive load and time for 10% to 90% of vOut is 10ms, how’s that compare to a normal 7905? 10ms of ramping up. OK. Well, I just checked an SGS-Thompson 7905 datasheet, there is no mention of time at all because it's going to be almost inst...
by mikeb
Mon Sep 07, 2020 4:49 pm
Forum: Technical questions
Topic: Issue 2 Oric-1 Repair
Replies: 21
Views: 1434

Re: Issue 2 Oric-1 Repair

. It doesn’t sound like the head is moving trying to find track Zero though so there is a ways to go. It may be already on track zero, so doesn't need to move. Provoke it (carefully) by manually winding the head out onto the disk, then see if you get a nice satisfying seek-to-zero noise. Some heads...
by mikeb
Mon Sep 07, 2020 4:44 pm
Forum: Hardware hacks and extensions
Topic: TSN 1-2450A instead of LM7905
Replies: 20
Views: 2203

Re: TSN 1-2450A instead of LM7905

I fitted the 2450A regulator again and the Atmos does boot if you short the Reset pin so I fitted a 4.7uf cap and had no joy but when I fitted a 10uf Capacitor the Atmos boots up so thanks to Mikeb for the tip on replacing the Cap with a higher value. OK, so that shows you how slow the module is at...