exxos & PP hard drive project.

General discussions or ideas about hardware.
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Re: exxos & PP hard drive project.

Post by exxos » Thu Dec 14, 2017 3:37 pm

I think the best option is to run all signals though PLD then any changes be easy to make. PLD will also give buffering for CF card.

I will re-try the external interface we used before when I get time. Though I think a internal drive will be easier for debugging. Also, we have 8mhz clock internal to generate delays, so wouldn't need monostable then either. Just use clocked 8mhz delays instead.
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Re: exxos & PP hard drive project.

Post by Petari » Thu Dec 14, 2017 4:05 pm

Every solution has it's good and bad sides.
With PLD is best to go on 16-bit variant for sure. Internal can be problem for many users. With PIO delays are not big problem - there is only 2 gate delay used. With DMA you need accurate delays on couple places. What we need most is delaying disappearance of CF cards from shops :lol:

Talking about internal, IDE type, so for CF cards. And because here someone said fastest. There is way to make much faster mass storage on Atari ST(E) .
And now the reasons why it would be better as internal:
It is for cartridge port. So is external. It is already fast, cartridge port is 16-bit. But for max speed it uses special hack mode, what needs small intervention in computer and leading couple lines out from case. Then it can achieve some 3.5 MB/sec on 8MHz Atari. Basically only on STE. The reason is simply that STE logic gate delays are much smaller than on ST, so signals on cartridge port have less delay - about 20nS instead 60nS .
If we go internal, we don't need slow ST logic, will use own chips. It works in PIO mode, it is tested, and very fast mode is reliable.
So, I would rather keep ACSI-CF as external, and go on ultrafast IDE IF as internal - when you want new design. And of course no Sandisk only for ultra fast mode.

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