[Simh] DEC Pro 350 Emulator

[Johnny Billquist]

On 2016-06-05 01:48, Alan Frisbie wrote:
> On 06/04/2016 04:27 PM, Johnny Billquist wrote:
>> On 2016-06-05 01:24, Al Kossow wrote:
>>>
>>>
>>> On 6/4/16 3:57 PM, Johnny Billquist wrote:
>>>> On 2016-06-04 23:50, Ray Jewhurst wrote:
>>>>> Speaking of files for the Pro, most of what I've found are IMD format
>>>>> which xhomer does not support. How difficult would it be to this
>>>>> functionality?
>>>>
>>>> I don't know what the IMD format is.
>>>
>>> David Dunifield's Imagedisk
>>> a source-available replacement for teledisk.
>>
>> Oh. So it's just a tool that can understand the teledisk format files.
>>
>> Anyway, unless people really want to recreate RX50 floppies, using a
>> 1.2M IBM PC floppy drive, those images aren't really that useful anymore.
>> For an emulator, you just want the contents of the files. If you want
>> RX50s, you're probably better off trying to find a real RX50 to write
>> the images.
>
> I'm slightly confused now.   I want to recreate real RX50 floppies
> so I can install DECnet in my real PRO-350.   Which format should I
> be using?
>
> Of course, I still need to get a real RX50 drive working again on
> another system -- probably on my old MicroVAX-II with a RQDX3.

It depends. teledisk, as well as ImageDisk, is a tool you run on a PC. 
Assuming that PC have a 1.2M 5.25" floppy, this tool can then try to 
write RX50 format floppies on that hardware, based on information stored 
in the image file.
That is, the image file format of these tools are a generic format and 
tool to recreate various different 5.25" floppies.
As you probably know, a DEC RX50 is rather different in the low level 
format to anything you'd find on a PC.

So recreating an RX50 on this hardware is a bit tricky, and chancy. The 
controller needs reprogramming, and you need to find some suitable 
media, and it's still not going to be perfect.

But this is what those files, and tools, are designed for. This also 
means that there is a lot more information than just the bytes of the 
floppies in there.

Now, as an alternative, you could grab the disk images I just put up, 
and on a real RX50, you just copy those files to the floppies, and you 
are good. The images I just put up are basically the result of just 
reading the content of all the sectors of the floppy, and putting that 
in a file. Like using dd on Unix, or VCP COPY on RSX (which is what I 
actually did).

So, with option 1, you do not need a real RX50 on some other system. But 
you are instead facing potentially multiple other issues, as you need a 
proper PC, with the right drive, right controller, and some suitable 
floppies to use for this.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
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