[Coco] DriveWire

[Bill Pierce]

Tormod, VCC relies on (in NitrOS9) an emulation of the RTC from Cloud9 (I think, may be Disto) or DW4 clock in the controllers (software clock will be used when non is present) and OS9's "sleep" call is based on the clock. I'm not sure how it handles it in RSDOS, but I know the timing does not speed up on operations which are clock based. Maybe the clock crystal emulation is involved, or just based on the PC clock to replace the clock crystal emulation. Not really sure (it is an emulator and therefore can use PC resources when needed or wanted).
It may be that it speeds up ram based instructions and not rom based instructions (like the 2 speedup pokes, makes more sense)... I do know that there are several programs that do not speed up.
You can try it yourself, just run VCC and run Lyra (or Ultimuse3 in OS9). Playing a song in both slow and fast CPU modes result in the same play speed. Then run Musica, it plays at whatever the speed of the cpu is set.

 

 


Bill Pierce
"Charlie stole the handle, and the train it won't stop going, no way to slow down!" - Ian Anderson - Jethro Tull

 

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-----Original Message-----
From: Tormod Volden <lists.tormod at gmail.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Sat, Feb 20, 2016 5:25 pm
Subject: Re: [Coco] DriveWire

On Sat, Feb 20, 2016 at 9:58 PM, Bill Pierce via Coco wrote:> Tormod, what you are probably not aware of is that VCC does not speed up the hardware clock. When the CPU is overclocked, the hardware clock remains the same speed and is not accelerated with the CPU. So any sofware using the hardware clock will not be affected, but software using software timing loops will be affected. I'm not sure if DW drivers are affected by this, but I run at 89mhz in NitrOS9 most of the time and have seen no timeout issues.I was not even aware there was a hardware clock! Is this a timer IC onthe CoCo3? The Dragon and CoCo1/2 certainly have no hardware clock.The DW drivers in HDBDOS just use CPU cycles for timing.Tormod-- Coco mailing listCoco at maltedmedia.comhttps://pairlist5.pair.net/mailman/listinfo/coco