Topic: Oric Atmos  (Read 2101 times)

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Offline Womble

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Oric Atmos
« on: May 07, 2009, 05:02:53 AM »
Hiya - just joined this site, am a long term retro fan, mainly concentrating on the repair of old systems (mainly arcade machine PCBs these days tho). Just read your page on the Oric Atmos and its got a fairly major error. It states that the Atmos is the same machine as the Oric 1 just in a new case, and that all software is compatible. This is not actually true. The PCB in the Atmos is the same as the one in the Oric 1, in fact the PCB still has "Oric 1" written on it in the Atmos machines. But they made a fatal mistake, they fixed bugs in the ROM that went into the Atmos. As a result a lot of Oric 1 games will not run on Oric Atmos machines as the ROM is somewhat different, basically the hardware is the same but the underlying operating system isnt. This was the final nail in the coffin for the Oric as suddenly there was confusion as to what games would and wouldnt run, Atmos owners suddenly had no guaranteed back catalogue of software, and Oric 1 owners were left wondering if software sold for the Atmos would work on their Oric 1. In reality the software industry just gave up on the platform so both parties lost out.

Sinclair had the option to fix the bugs (and there are about a dozen) in the Spectrum ROM for the plus and the 128K machines (in 48K mode)  but thankfully he saw sense and left them unchanged. Fixing bugs is all well and good as long as you don't need more space where the fixes slot in. If you move the start of ROM routines around you break software compatibility, ROM routine calls just specify the start address in the ROM for that routine, if this changes the software will invariably crash. So Tangerine Computers made a major mistake in trying to make their machine better and ended up killing the platform dead.
« Last Edit: May 07, 2009, 11:53:12 AM by Womble »
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Offline AndyRCM

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Re: Oric Atmos
« Reply #1 on: May 07, 2009, 07:11:01 AM »
@Womble - wow mate thanks for that! Very useful stuff there! It answers a lot of questions about loading problems then too.
Do you know why is there a major change in memory available too . . . on the Oric 1 it says something like 47k and on the Atmos it says 37k . . . ?

Andy
« Last Edit: May 07, 2009, 07:49:53 AM by AndyRCM »
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Offline woody.cool

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Re: Oric Atmos
« Reply #2 on: May 07, 2009, 07:36:46 AM »
Sinclair had the option to fix the bugs (and there are about a dozen) in the Spectrum ROM but thankfully he saw sense and left them unchanged. Fixing bugs is all well and good as long as you dont need more space where the fixes slot in. If you move the start of ROM routines around you break software compatibility, ROM routine calls just specify the start address in the ROM for that routine, if this changes the software will invariably crash. So Tangerine Computers made a major mistake in trying to make their machine better and ended up killing the platform dead.
... but when Amstrad bought the Sinclair machine, they fixed some of the bugs, hence the incompatibilities with +2s and +3s.

Offline Womble

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Re: Oric Atmos
« Reply #3 on: May 07, 2009, 11:50:09 AM »
@Womble - wow mate thanks for that! Very useful stuff there! It answers a lot of questions about loading problems then too.
Do you know why is there a major change in memory available too . . . on the Oric 1 it says something like 47k and on the Atmos it says 37k . . . ?

Andy

I do actually - the different ROMS boot the machines into slightly different modes, on the Oric 1 it default boots to low res mode, whereas on the Atmos the default boot state is high res mode, which reserves the missing amount of RAM for high res gfx. There is a command to get it back tho, RELEASE or GRAB, something like that. Too much on my Retro Fettling bench to boot my Orics at the moment, but that's the jist of it.

Yes, its a right royal PITA to work out if your game is not loading because its Oric 1 only, or Atmos only, or just because the Oric is a very very fussy loader at the best of times. I built a small amplifier box to load games from my ipod on to a speccy, but I have found the most reliable way on the oric is to just play the WAV on the PC and connect the headphone jack on my speakers to the Oric input, very low tech but the Oric seems happier.

One thing you could usefully also add to the descriptions concerns the power supply, yes its 9V and 600 mA like the spectrum 48K PSU, but the Oric needs the opposite polarity to the Spectrum. Every retro fan has a speccy PSU or 3 kicking about, but these are instant death to an Oric unless an adaptor is made to reverse the polarity.

The reliability problems you mention stem mainly from the fact that Tangerine used faulty RAM chips from the outset, chips that had failed the chip makers internal QC. Tangerine bought the scrap bins for a nominal fee and went through them trying the chips to find ones that just about limped along enough to be used in the Orics. This led to massive reliability problems with RAM chips that died early on in life, faulty Orics often pop up on ebay and its almost always bad RAM, unless they have been "tried" with a speccy PSU.

Sinclair did something similar with RAM tho, the upper RAM in a spectrum (i.e. the 32KB that's added to a 16KB model to give 48K) is actually 64KBs worth of chips. He bought chips that were half faulty and wired it up so only the upper or lower half of each chips address space was used. There is a link on the PCB to set which half is actually enabled. Made for a tidy cost saving too.
« Last Edit: May 07, 2009, 01:41:12 PM by Womble »
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Offline billdooruk

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Re: Oric Atmos
« Reply #4 on: May 07, 2009, 02:32:50 PM »
Nice info....

I know my oric 48K is a fussy thing to load....

Hopefully I can get my newly aquired Manic Minor to run for the open day.

Offline AndyRCM

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Re: Oric Atmos
« Reply #5 on: May 07, 2009, 02:40:01 PM »
Can you stop mentioning that you have Manic Miner . . . :(

You know I collect MM and JSW for various systems! LOL!
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Offline billdooruk

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Re: Oric Atmos
« Reply #6 on: May 07, 2009, 02:57:58 PM »
That's why I keep mentioning it  ;)

Offline AndyRCM

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Re: Oric Atmos
« Reply #7 on: May 07, 2009, 02:58:42 PM »
That's not nice!  :P
"I could see the faces of those who led pissing themselves laughing" - Funeral Pyre by The Jam