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Posted By
seff
on 2021-01-31
07:57:30
 |  Re: Atari people asked about the Plus4 and I gave him a lecture :)
>The Plus4 PAL has an ability to be turned in super turbo mode which switches CPU to incredible 2.2 MHz and this makes it one of the fastest 8-bit computers. However it is quite likely that nobody knew about this mode in the 80s.
Litwr how do you do that?
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Posted By
siz
on 2021-02-01
03:30:55
| Re: Atari people asked about the Plus4 and I gave him a lecture :)
You switch TED to NTSC clock divisor on a PAL system. It will generate a higher clock because the pixel clock is higher (~17MHz PAL, ~14MHz NTSC) and divisor is less (perhaps 16 for PAL and 14 for NTSC, I'm not sure and too lazy to check it) the resulting clock will be higher (of course turning screen off is required to avoid single clock during screen drawing).
I'm pretty sure some of the crunchers used this mode back in the late 80s, early 90s (maybe Cruel Crunch?).
Nowadays I hate this things as there is no real benefit to use anything that CPU intensive on a plus/4 while you can do it on a PC much faster. And my display hates non-standard display timings so every time one of these occurs I have to reset my RetroTink2X and monitor. So please, don't. 
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Posted By
MIK
on 2021-02-01
04:03:29
 | Re: Atari people asked about the Plus4 and I gave him a lecture :)
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Posted By
seff
on 2021-02-01
13:55:11
| Re: Atari people asked about the Plus4 and I gave him a lecture :)
Well yes, NTSC + screen blanking + DRAM refresh for each line.
I thought I was missing something.
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Posted By
JimmyCoupe
on 2021-02-01
08:52:10
 | Re: Atari people asked about the Plus4 and I gave him a lecture :)
I actually upgraded my Commodore Plus/4 to an 800XL. At the time I thought it was a big upgrade but years later my thoughts are not as clear as then. I know this is a little of piece but the 8bit Atari's did have an excellent early year back catalogue of some excellent games, it really did often outshining the C64.
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Posted By
MMS
on 2021-02-07
18:24:16
 | Re: Atari people asked about the Plus4 and I gave them a lecture :)
OK, maybe it is a too wild hypothesis, but what if the newer (not classic) games with those decompressors played a role in the high death rate of 8501 CPUs? I mean the CPU is alread hot, then we force with those recrunchers into an even higher temperature. The heatsink was not typical in the past, as the early C16s had real metal EMC shiled, played a radiation surface too. but the thermal paste dried out over the time.
Initial articles in the 80s did not speak about high defect rate (as far as I can read), high defect rate of 8501s became known later.
Maybe classic games did not force the CPU so much?
Would be interesting to measure the temperatures during a longer decompression, like an older MB game, how much it increases. AFAIK the tests till now happened in a normal "BASIC" mode, not calculating with such overclocking or the extra tasks the CPUs do (we know in PCs, that even with fixed clock speed the CPU can get warmer with more tasks. Why it should be different on the 8 bits? eg. SID digi converter pushing CPU to it's limits. Initial games did now give so much tasks to the CPU)
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