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Messages - carlsson

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Remember to reverse the Spectrum polarity so you get centre positive which is what the Oric will want.

I have an Oric on which certain keys lock up the machine when pushed. I got help replacing the 6522 previously, but I have understood that the raw decoding of the keyboard goes through the AY-3-8910 sound chip, also known as PSG. I haven't got to replace that one yet, but I hope when replacing it, my Oric will entirely spring to life. At least a majority of the keys register correctly on mine.

« on: August 27, 2015, 11:26:09 PM »
Bumping this old topic, due to I just brought out my CGL M5 from the closet and found that I was wrong, and 3fish was right.

The markings on the actual PSU says 240V AC 50 Hz input, and the following outputs:
-12V 0.03A
+12V 0.4A
+5V 0.8A

This is conflict with the schematic found on the Internet, which clearly says +5V, +12V and -5V. Either the label on the PSU has the wrong markings, or the schematic does. Not that I really need to know at this minute, but in an attempt to collect power requirements - both voltages, minimum amperes, polarity where it matters etc - it made me wonder if the M5 needs the -12V or the -5V. Even at a so low current as 0.03A, it should make a difference which one you feed.

GENERAL RETRO CHIT CHAT / Re: Sord M5 multicart
« on: January 03, 2015, 08:49:33 PM »
That's the diagram I used. I just wired a ps2 cable into the switches of a joypad with, like you say, 2 diodes connecting the fire & direction lines.
After not touching this project for three years, I recently came across a half dozen PC compatible joypads that were on their way to recycling despite being fully functional. My heart said that electronics want to be rescued and repurposed, so I took care of them.

Some modding will be required on the joypad PCB due to how those pads wirk on the PC. Now I thought I'd be clever and snip off a PS/2 cable from a used up keyboard. but I soon realized that the standard wiring for both PS/2 keyboards and mice is to only use four of the six pins, while the Sord M5 obviously uses all six pins.

When you made your hack, did you start off with solderable 6-pin mini-DIN connectors and put your own cable onto it, or did you happen to come across some used keyboard where the manufacturer actually connected all six wires despite two of them weren't needed? Since the typical keyboard and mice connectors are moulded, it doesn't work out so well for me to hack it open and solder, I'd better get some fresh connectors in that case.

Around 60 programs available by the end of 1982? Hm, gotta be a number of type-ins by the Japanese. I was recently asked how many M5 cartridges were ever released. There is a Japanese web page that seems to cover them all, which makes for a little over 30 cartridges counting various Basics, productivity software and hardware expansions. Even with the known amount of tape releases, we'd have a tough time hitting 50 titles.

COLLECTORS CORNER / Re: Carlsson's Collection
« on: October 10, 2012, 04:50:52 PM »
Very few changes in the past year:

* One BBC Micro is probably on its way to a new home.
* One Creativision also is seeing a new ownership.
* ZX Spectrum 48K not only broke, but it is also missing.
* I'm having a Philips Videopac G7000 on long term loan.
* I picked up another loose C64C, but who doesn't?
* I got a VTech Laser 500 in a nice leather suitcase.
* I picked up a boxed Atari 520STM (no floppy) for £~3.75.

CODING AREA / Re: What are you working on?
« on: October 10, 2012, 04:42:37 PM »
The other week I implemented a VIC-20 variant of the bonus game from Tapper, to be used in a prize competition. Now I'm considering if I should implement the main game as well... ;)

CODING AREA / Re: 8 BIT Basic Game Contest
« on: October 10, 2012, 04:25:11 PM »
Nice initiative, but I'm slightly confused about the rules. You may not include inline assembly (or in the form of DATA statements to be POKE'd and then run), but you may use a wide row of 3rd party Basic extentions and even compile your game which will cause it to look like machine code anyway? Back in the days, very few of the listings in the magazines relied on Basic extentions, just so it should work for anyone. In this set of rules, it seems even GEOS is allowed on the C64 platform.

While a multi-platform event never can have 100% fair rules, I think it should be a little more strict and equal when it comes to hardware and size limitations, language features and so on. I'm sorry if this comes out as bickering.

Anyway, I'm having a hard time developing a polished game in Basic. Nowadays I think it is fine for prototyping or CSSCGC entries, but for anything that I'd like to be proud about, I think I would involve so much machine code (or even compiled C etc) that it would be disqualified anyway.

GENERAL RETRO CHIT CHAT / Re: Blimey, I'm sitting on a goldmine !
« on: October 01, 2012, 04:21:22 PM »
You know what they say about middle-aged men with "Porsche"s. ;)
Just that the Porsche part is a combination of misconception and myth. They were proposed to design a case, but according to the story I've read it was too impractical so Commodore went back to Ira Velinsky to design a new (rounded) case which is what the 8032-SK, 8096-SK, 8296, CBM 600 (B128), CBM 700 (B256) etc are using. However I've seen a number of SK PET's on eBay recently playing on the Porsche relation, which says something about how strong that brand name is if they get credited 30 years later for something they never actually did...

Out of curiosity, did you make any progress? IMHO, the 6502 is one the last chips to break and if it did, it is likely a number of other chips broke as well. As for the ROM, it should be possible to wire up an adapter for a 2764 EPROM or any more sophisticated solution.

HARDWARE/SYSTEMS DISCUSSION / Re: your latest Retro computer purchases
« on: September 11, 2012, 11:09:50 AM »
Quote from: John Heywood (1546)
When all candles be out, all ZX Spectrums be gray.

GENERAL RETRO CHIT CHAT / Re: Worst mistake made while collecting...
« on: September 05, 2012, 12:14:14 PM »
I got a free TRS-80 Model III from the US, just had to pay shipping ~$170 or so. Upon arrival, it had come loose and imploded. Despite the package was insured, USPS didn't want anything to do with it, claiming it was a matter of the Swedish post. Those in turn didn't want anything to do with it, returning it back to USPS. In the end, I had a smashed TRS-80 and a small pile of glass shards in my living room and was $170 lighter. I couldn't stand keeping the computer corpse so I donated it to a friend who didn't mind.

FOR SALE / WANTED / Re: On Ebay P500?
« on: September 03, 2012, 10:42:43 AM »
Another one? This summer one loose and one boxed P500 have been up on eBay. I didn't follow how sales went, so perhaps this is the same boxed unit that was relisted twice. Supposedly those are so rare (even in European/German edition) that three different P500 in the same summer would be suspiciously many.

HARDWARE/SYSTEMS DISCUSSION / Re: Cheap computing in the 80's
« on: July 11, 2012, 12:18:35 PM »
Not sure of the date of this ad
Issue 8410 equals October 1984. To get a fair comparison, we can check the multi-page advert from Spectrum the computer seller (as opposed to Sinclair the computer manufacturer) in the same issue:

Oric-1 (16K) at £55.95 (Atmos not officially priced)
Atari 600XL at £99.99
ZX Spectrum 48K incl. software "Spectrum Six Pack" at £129.95
Commodore 16 incl. tape recorder at £139.99
Atari 800XL at £199.99
Spectravideo SVI-328 at £199.95
Acorn Electron at £199.95
Memotech MTX512 at £275
Commodore Plus/4 at £299.99
BBC B incl. tape recorder and 5 games at £399
Sinclair QL at £399
Commodore SX-64 incl. MPS-801 and 3 business programs at £799

Atari 1050 floppy drive at £199.99
Commodore 1541 floppy drive at £229
Cumana CSX100 (BBC) at £129.95
Cumana CS100 (BBC) at £159.99
Cumana CD800S (dual drive, BBC ??) at £419.95
Opus 5401 at £149.95
Opus 5802 at £199.95
Opus 3402 3" at £229.95

Curiously enough, Spectrum didn't advertise a single C64 in that eight page long advertisment. Perhaps the price war was going so strong that it made no sense advertising it.

So yes, compared to a 48K Spectrum or 64K Atari 800XL, the 64K MSX machines at £299 each were a bit steep. However compared to a Plus/4 for £299 or a somewhat aging BBC B with tape recorder and a few games for £399, it wasn't completely out of line.

As a side note, I saw an advertisment for Protek joystick interfaces. The one for BBC (to connect Atari style joysticks) cost £11.95 or £19.95 including Quickshot joystick. The corresponding interface for ZX Spectrum which is compatible with both Kempston and Sinclair cost £19.95 or £29.95 including joystick. Fast forward to today, and a Protek BBC interface will easily fetch £11.95 and much more on eBay, while ditto Speccy interface probably will only cost half as much. That is an interesting change of value over the years.

« on: July 05, 2012, 03:08:20 PM »
My impression is that the SID is so relatively self-contained that it can be interfaced to most systems, perhaps even through I/O port addressing instead of memory mapped I/O?

The availability of software is another matter, and I suppose 6502 based computers could have an advantage. SID on Plus/4 is a staple, SID on VIC-20 has been implemented enough times to create disambiguity where in the memory map the chip should be put. I have a vague memory someone did SID on Oric too, which probably is in the same order of magnitude as SID on Beeb or Atom.

« on: July 03, 2012, 01:24:12 PM »
Except pin 5 should be -5V, not -12V as per the schematic you linked to?

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