Nina's Diary Program

[phaeron]

1 hour ago, tschak909 said:

I know I said I wasn't going to try hi-speed SIO (USDoubler), but..

 

I'm getting conflicting information on hi-speed, it seems that setting the audfX channels isn't sufficient, I have to bit-bang the bits myself? (meaning I can't use SIOV?)

The OS SIO routines don't have built-in support for customizing transfer rates. SIO sets AUDFn directly for 19200 baud, so the only way to use them for high speed is to either copy them to RAM and patch them (which only works for specific OSes) or try to inject code into the SIO processes to change the baud rate at the right time.

 

I have seen a hack where the SIO serial interrupt routines are hooked to implement XF551 high-speed mode by switching the baud rate right before the data frame. US Doubler is different as the command frame also has to be sent at high-speed. Typically the first byte of a send operation is kicked manually by writing directly to SEROUT, which makes finding an appropriate interception point more difficult. But then you still have all the other fun of US Doubler style high-speed to deal with, like drives that use speeds that are too high for interrupt-driven operation, drives that don't activate USD high speed mode until the speed is queried, drives that corrupt bytes in high speed mode if you don't enable other options, etc.

 

[Alfred]

What Phaeron said.

 

If the user has a BlackBox, or an UltraSpeed OS ROM from CSS they can get high speed for some devices via SIOV, but you probably can't count on it. I don't know if any of these other upgrades like U1MB etc. offer hi-speed SIO routines. Best to just include your own, if you have room in the cart, might run about 1K or so I think. Hiassoft (sp?) has posted here somewhere a fairly complete hi-speed SIO code block that does just about every device IIRC, probably more than 1K for that.

[tschak909]

Would anyone want to buy a copy of this in the AtariAge store with box/manual?

 

-Thom