[Coco] OS-9 RAM disk with "rdisk" command? And /md descriptor?

[L. Curtis Boyle]

MODPATCH was the “official” OS-9 utility that allowed editing modules in memory. the /MD descriptor was different in that it let you edit all of memory - system ram, modules, data areas, screen displays, hardware addresses, etc.

L. Curtis Boyle
curtisboyle at sasktel.net



> On Jan 31, 2015, at 10:12 PM, Bill Pierce via Coco <coco at maltedmedia.com> wrote:
> 
> 
> I have a program that will edit modules in memory while running... as well as any memory locations.
> It works just like ded with the same interface, it called "med" and I've used it for years to edit system modules before cobblering a bootdisk.
> I noticed it's on one of Brother Jeremy's "Update Disks" but I had it long before those disks ever surfaced.
> 
> 
> Bill Pierce
> "Today is a good day... I woke up" - Ritchie Havens
> 
> 
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> 
> -----Original Message-----
> From: Allen Huffman <alsplace at pobox.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Sat, Jan 31, 2015 11:02 pm
> Subject: Re: [Coco] OS-9 RAM disk with "rdisk" command? And /md descriptor?
> 
> 
>> On Jan 31, 2015, at 9:39 PM, Gene Heskett <gheskett at wdtv.com> wrote:
>> 
>> Probably because you were out of the os9 neighborhood when I wrote that.  
>> md is the descriptor that goes with myram, an automatic ramdisk I wrote 
>> quite a while back.
> 
> Nope, this is the one Curtis is talking about. It allows you to dEd through 
> memory. As soon as he said that, I remembered it. I don’t remember where it came 
> from, though.
> 
>> If it (md.dd) and myram (myram.dr) are in your 
>> bootfile, and you issue a dir /md, there will be a slight pause, 200 
>> milliseconds maybe, while it allocates the ram it needs and formats (does 
>> not use the format command for this) a ramdisk whose size is determined by 
>> one var in the descriptor, cyl. The dir command is held in sleep till this 
>> is done, and then it wakes and dutifully reports an empty disk. The number 
>> of cyl's is the number of 8192 byte blocks of ram it allocates.  None of 
>> the other placeholder vars in the descriptor are used.
> 
> Clever — that’s a nice improvement over the “iniz / format” approach of most 
> others.
> 
>> Any access, even it the first access is a write, is held until the 
>> automatic formatting has been done, and then the write will be done as you 
>> requested.
> 
> That’s cool The Microware official RAM disk (non-6809) was like that… iniz would 
> set it up. In fact, format wouldn’t even work on that.
> 
> I didn’t like RBF devices that didn’t act like normal RBF devices, so while I 
> was working for Microware, I actually wrote my own RAM disk driver called VDISK. 
> It honored ALL the settings in the descriptor (not just the ones Microware’s 
> did) so I could dmode it to match a floppy disk and to a “backup /d0 /r0” — 
> something most RAM disks didn’t allow.
> 
>> The myram.README on my web page uses /r0 for the descriptors name, but 
>> that clashed with the rammer/ro kit, so when it was added to the repo, the 
>> descriptor was renamed to make it distinct from rammer.  Tested at up to 
>> about 1.7 megabytes of usable ramdisk on my 2 meg machine.  I intended for 
>> it to Just Work(TM) and I believe it does.
>> 
>> And when you are done, a simple deiniz /md returns every byte it used to 
>> the free memory pool.  Restarting it after changing the cyl to some other 
>> value does not recover what was there when it was deiniz’d.
> 
> 
> I would expect no less from any RAM disk. Was this a problem with others? I 
> noticed some devices I have under my NitrOS-9 boot disk CRASH if you deiniz 
> them. That sounds like a poorly written driver to me, since you’d think the 
> driver would just return an error in the deinit routine if it couldn’t do that.
> 
>> Enjoy Allen, I think you will like it.
> 
> I may look in to it if the one I am used to won’t work under current NitrOS-9. I 
> liked being able to change the size with one command. I suppose if I booted with 
> yours, and it was set to some size, in order to change it I would have to:
> 
> deiniz /md
> dmode /md new settings
> 
> …then the first use would set it back up. I guess that’s not too much more than 
> the rdisk approach but man, rdisk spoiled me.
> --
> Allen Huffman - PO Box 22031 - Clive IA 50325 - 515-999-0227 (vmail/TXT only)
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