[Coco] a not very important drivewire question
ooogalapasooo at aol.com
Thu Jul 17 13:29:04 EDT 2014
@Robert Hermanek, my HDBDOS build is "current" and I get the same FC error when trying to use "DRIVE #255".
So I think Robert Gault is correct in his assumption. Since almost all the functions of HDBDOS are limited to 255 (drives, disks ect), the "-1" could probably be removed though I haven't checked the code to see if it's used as a constant for anything else not drive or disk related.
Not having any use for that many drives, I had never tried the command with 255. Which in reality, if you tried to mount 256 full size VHD images in drivewire, your computer would run out of memory long before you would get to vhd 255. I have 4 gig of mem on my PC and get memory warnings when I open other programs while DW4 is running with 8-20 VHD images loaded. Also, I run multiple instances of drivewire so that contributes to the memory use (and vhd count) as well. But I have noticed, the more vhds I load the more dw4 "lags" on some things. Also, the higher the sector number when reading and writing, the slower the transfer. This only makes sense as dw4 would have to seek from the beginning of the vhd/dsk file for each sector therefore taking it longer as the sector number gets higher. You can really see this when backing up one vhd to another. It gets slower and slower.
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From: Robert Hermanek <rhermanek at centurytel.net>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Thu, Jul 17, 2014 12:27 am
Subject: Re: [Coco] a not very important drivewire question
No, I think we're just dealing with assembler constants here... so when
the comparison is with MAXDN-1 at assembly time, we're dealing with
255-1 = 254. I guess the question is, why is the "-1" there? Maybe
MAXDN = 255 is fine, and the -1 should disappear... anyway, as Robert G
mentioned, would be curious if others can do DRIVE #255, keeping in mind
the "#" is important, referring to the device #, not the disk number.
But, as I mentioned, not that important... I can scrape by with 0-254,
so 255 devices X 256 disks per device = mega storage :) Was just
curious. I have a home-brew drivewire server, and I was setting it up
to take any DSKO activity to Drive # 255, disk 255, track 34 sector 18,
to be considered output to a virtual printer, allowing coco programs to
easily pass data to a DWP 220 I've got sitting here attached to my PC...
that's why it came up.
On 7/16/2014 10:01 PM, Gene Heskett wrote:
>> the value of MAXDN for DW be changed to 256.
> Whats the data size of MAXDN? 256 is a 2 byte value, as its 0x0100, and
> needs an int to store it.
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