Pokey Divisor 0

[TonVH]

I am trying to understand what this is? Is it a bit of software or hardware. I read allover that it can speed up datatransfers but see no place where it can be ordered.

 

[+DrVenkman]

SIO speeds are measured in terms of “POKEY divisors” - standard SIO rate of 19200 bps is - I think - POKEY divisor 6 (I might be misremembering). Through a properly constructed interface without electrical interference, and with a modified Atari OS, you can run the interface at a lower divisor and thus a faster speed. The fastest speed possible is divisor 0, which is 125,000 bits per second.

[TonVH]

So does that mean that the present OS (in a Romchip?) will have to be switched with a modified one? Where can I get a modified one and is the rom socketed?

[Roydea6]

http://www.horus.com/~hias/atari/hipatch-1.30.zip

 

This zip file has a patch program that will allow you to patch the rom in your Atari. And another program to dump that patched rom to a file on diskette, floppy, sio2pc emulated floppy or hard drive if you have one... Under emulation it is quite fast and easy. Then using the patched rom and an eprom's burner put it into a new 74128 socketed rom. If you have none of these requirements it will cost about 60.00 USD to set up.

[TonVH]

Do-it-yourself! Nobody makes the rom's and sells them? It seems a bit overkill to get all that stuff for a one-time thing.

[+DrVenkman]

Well you also didn’t mention your end use and equipment you intend to use high speed I/O with. Bear in mind physical disks don’t run that fast. Three time standard is about the most you can usually do with a physical floppy and even then, you need a modified drive. For an SIO2PC device you can boot a patched DOS that includes the fast I/O routines.

[TonVH]

I'm thinking about one of those Sio2 devices. Most likely Sio2USB or Sio2SD. Besides the Atari I use a iMac.

[Wilheim]

SIO speeds are measured in terms of “POKEY divisors” - standard SIO rate of 19200 bps is - I think - POKEY divisor 6 (I might be misremembering). Through a properly constructed interface without electrical interference, and with a modified Atari OS, you can run the interface at a lower divisor and thus a faster speed. The fastest speed possible is divisor 0, which is 125,000 bits per second.

 

Actually, for 19.200 bps it uses a divisor of $28 (40 dec). 3X uses a pokey divisor of $08.

[Rybags]

Annoyingly the divisor is hard-coded into SIO which is why you need replacement OS or routines.

Also there's a limit beyond which the normal IRQ method won't work and software polling has to be used (something like 4 and under?)

[Mathy]

Hello Ton

 

I'm thinking about one of those Sio2 devices. Most likely Sio2USB or Sio2SD. Besides the Atari I use a iMac.

 

SIO2USB or SIO2PCviaUSB? The first is a device to connect a USB memory stick to the Atari, the latter connects a modern computer to the Atari.

 

Sincerely

 

Mathy

[TonVH]

Sio2USB so for connecting a USB-stick. I think that all available software can be mounted on a stick.Only I don't like the idea of having to create a new Rom. I have no trust (based on experience) in my skills for this type of craftsmanship.

 

I've also looked at "The Cart" but the problem there is getting it filled with the software and then there is (I presume) also the Pokey stuff. Makes it all a bit complex. Would be nice if "The Cart" could be filled on a PC/Mac. But I see no solution that way.

[_The Doctor__]

You could always get someone to fill whatever device for you...