Re: [Simh] RP vs RM header operations

[Lars Brinkhoff]

Rob Doyle wrote:
> As a clarification, it looks to me like the sector header data "words"
> are always 16-bit, regardless if the disk pack is formatted for 16-bit
> data or 18-bit data.

That's how I understood it too.

> From a hardware point of view, sector header "Word 3" and "Word 4"
> have no particular meaning.  Just for completeness, can you point me
> to a reference where "pack number" is defined or used by the software?

Here's where the pack number is written to the header:
https://github.com/PDP-10/its/blob/master/src/kshack/nsalv.261#L5399-L5401

And here's where it's read back:
https://github.com/PDP-10/its/blob/master/src/kshack/nsalv.261#L5107-L5109

I don't know why it's done this way.  It seems to go back to the Systems
Concepts DC10 disk controller for the AI lab KA10.

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Re: [Simh] RP/RM differences in header commands (for ITS, salvager)

[Rob Doyle]

On 6/26/2019 9:54 PM, Lars Brinkhoff wrote:

SALV actually writes data for an entire track all in one go.  I tried
something which skips the headers in the middie.  But there must be
something else wrong with my code, because when reading back the sector
data I just get zeroes.

Anway, I agree something like that would go most of the way to make SALV
happy.  There's another part of SALV that reads the header information
go access the pack number written there, but I'm not sure how that
number is used later.


I think that should work. When executing the "write header plus data"
command, the state machine in my FPGA's RP06 controller just handles the
first two 36-bit words (technically four 16-bit words) specially and
jumps to the "write data only" states to transfer the non-header data.
Ditto read and write check commands.

This part of the FPGA passes all of the RP06 diagnostics - so I believe
it is correct.

From a hardware point of view, sector header "Word 3" and "Word 4" have
no particular meaning.  Just for completeness, can you point me to a
reference where "pack number" is defined or used by the software?

Rob Doyle







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Re: [Simh] RP vs RM header operations

[Rob Doyle]

On 6/27/2019 11:27 AM, Bob Supnik wrote:
As I suspected, RP class drives (except the RP07) have 4 words of 
header, and RM class drives have 2. This is confirmed by the RSTS/E disk 
initialization code. RSTS/E can't format an RP07, so I can't verify how 
those functions ought to work. RSTS/E seems to think it has 2 words of 
header, though.


Any implementation of the write/write check/read header functions needs 
to take care of the header words properly. Assume, for example, that 
SALV is trying to write an entire RP06 track (20 sectors/track). It 
would specify a Massbus  count (in 18b words) of 20 * (4 + 256) = 
5200 words. If write track plus header just defaults to being a normal 
write, then 80 words will spill over to the start of the next track. 
That might not matter if the next track is promptly overwritten, but on 
the last track, the extra words will generate an addressing error, and 
SALV will (probably ) fail.


For an RM, the count needs to be 30 * (2 + 256) = 7740 words. Again, if 
the two extra words aren't accounted for, the last track write will 
overflow and generate an error.


RSTS/E formats both RPs and RMs the same way: cylinder (plus 16b flag) 
in the first word, track/sector in the second. For the RP, the third and 
fourth are left as 0. There are bad block flags reserved in the header, 
but all SimH disks are perfect. ;)


tl;dr. If you're going to implement these functions as other than stubs, 
they better be done right, or other kinds of errors will surface.


/Bob



Referring to 
 
Figure 2-6:


As a clarification, it looks to me like the sector header data "words" 
are always 16-bit, regardless if the disk pack is formatted for 16-bit 
data or 18-bit data.  I suppose that makes sense so that either type of 
system can read the sector header correctly.


Rob

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Re: [Simh] The Interconnect Task Force

[Johnny Billquist]

(Hooray for automatic spell correction...)

On 2019-06-27 11:02, Johnny Billquist wrote:
I'm pretty sure the ones I ever saw had so or sti and were connected to 
an hsc.


so was meant to be sdi. So, sdi or sti is what I seem to remember ours 
had. I think we might still have one or two drives somewhere, but we 
don't have any media...


  Johnny



Johnny

Matt Burke  skrev: (27 juni 2019 09:58:14 CEST)

On 26/06/2019 04:28, Robert Armstrong wrote:

Thanks, but I was more interested in the details of LESI if they are
available. LESI was another mass storage "bus" that supported
both disk and
tape (albeit with exactly one example of each).

There is also the RV20 write-once optical drive which used LESI.

Matt

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Re: [Simh] RP/RM differences in header commands (for ITS, salvager)

[Johnny Billquist]

Sorry, I did oversimplify it, yes.

Essentially, I meant that you should write the data part as a normal 
write, and ignore the extra fluff required for the write header. That 
ought to make most software happy.


So, skipping extra words intended for the header, adjust size accordingly.

  Johnny

On 2019-06-27 04:05, Bob Supnik wrote:
I don't think it's that straightforward. The write header and data 
command must include the proper Massbus word count for header and data. 
The Unibus side of the RH11 is doing 18b transfers, and so is the disk 
side, so the word count ought to be 260 for an RP and 258 for an RM.


If the simulator doesn't "skip" the right number of header words, SALV 
is going to fail on its block data check.


/Bob

On 6/26/2019 7:37 PM, simh-requ...@trailing-edge.com wrote:

I would vote for someone doing just the naive write as a starting point.
I think much software will be happy enough with just that, and then we
can look at specific when we locate software that really do care about
what is written into the headers.

    Johnny


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[Simh] RP vs RM header operations

[Bob Supnik]

As I suspected, RP class drives (except the RP07) have 4 words of 
header, and RM class drives have 2. This is confirmed by the RSTS/E disk 
initialization code. RSTS/E can't format an RP07, so I can't verify how 
those functions ought to work. RSTS/E seems to think it has 2 words of 
header, though.


Any implementation of the write/write check/read header functions needs 
to take care of the header words properly. Assume, for example, that 
SALV is trying to write an entire RP06 track (20 sectors/track). It 
would specify a Massbus  count (in 18b words) of 20 * (4 + 256) = 
5200 words. If write track plus header just defaults to being a normal 
write, then 80 words will spill over to the start of the next track. 
That might not matter if the next track is promptly overwritten, but on 
the last track, the extra words will generate an addressing error, and 
SALV will (probably ) fail.


For an RM, the count needs to be 30 * (2 + 256) = 7740 words. Again, if 
the two extra words aren't accounted for, the last track write will 
overflow and generate an error.


RSTS/E formats both RPs and RMs the same way: cylinder (plus 16b flag) 
in the first word, track/sector in the second. For the RP, the third and 
fourth are left as 0. There are bad block flags reserved in the header, 
but all SimH disks are perfect. ;)


tl;dr. If you're going to implement these functions as other than stubs, 
they better be done right, or other kinds of errors will surface.


/Bob


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Re: [Simh] The Interconnect Task Force

[Matt Burke]

Maybe there was an upgrade kit for the RV20 like the TU81 to TA81 kit which converts it from LESI to STI.Internally the RV20 appears to use SCSI.MattOn 27 Jun 2019 10:02, Johnny Billquist  wrote:I'm pretty sure the ones I ever saw had so or sti and were connected to an hsc.  Johnny Matt Burke  skrev: (27 juni 2019 09:58:14 CEST)
On 26/06/2019 04:28, Robert Armstrong wrote: Thanks, but I was more interested in the details of LESI if they are available.  LESI was another mass storage "bus" that supported both disk and tape (albeit with exactly one example of each).There is also the RV20 write-once optical drive which used LESI.MattSimh mailing listSimh@trailing-edge.comhttp://mailman.trailing-edge.com/mailman/listinfo/simh-- Skickat från min Android-enhet med K-9 Mail. Ursäkta min fåordighet.___
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Re: [Simh] The Interconnect Task Force

[Johnny Billquist]

I'm pretty sure the ones I ever saw had so or sti and were connected to an hsc.

  Johnny 

Matt Burke  skrev: (27 juni 2019 09:58:14 CEST)
>On 26/06/2019 04:28, Robert Armstrong wrote:
>> Thanks, but I was more interested in the details of LESI if they are
>> available.  LESI was another mass storage "bus" that supported both
>disk and
>> tape (albeit with exactly one example of each).
>>
>There is also the RV20 write-once optical drive which used LESI.
>
>Matt
>
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Re: [Simh] The Interconnect Task Force

[Matt Burke]

On 26/06/2019 04:28, Robert Armstrong wrote:
> Thanks, but I was more interested in the details of LESI if they are
> available.  LESI was another mass storage "bus" that supported both disk and
> tape (albeit with exactly one example of each).
>
There is also the RV20 write-once optical drive which used LESI.

Matt

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Re: [Simh] IS there a BASIC available for DG Nova ?

[Peter Onion]

On Thu, 2019-06-27 at 00:40 -0600, Bruce Ray wrote:
> Note that an on-line Nova emulator is available at:
> 
> http://www.novasareforever.org/novajs/index.php
> 

Thanks Bruce,

I'll pass that on :-)

PeterO






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Re: [Simh] IS there a BASIC available for DG Nova ?

[Bruce Ray]

Note that an on-line Nova emulator is available at:

http://www.novasareforever.org/novajs/index.php




Bruce Ray
Wild Hare Computer Systems, Inc.
Boulder, Colorado USA
b...@wildharecomputers.com

...preserving the Data General legacy: www.NovasAreForever.org

On 6/27/2019 12:23 AM, Peter Onion wrote:

(Long time lurker here !)

A friend of mine has just building a paper tape reader to read some only tapes 
has has
from his college days in the 1980s.

He says "The machine at college was a Data General Nova and we only had access to 
BASIC!"
so I thought I would ask here if there is anything that might be able to run 
his old
programs again.

Once he's read a tape I'll post a sample here.

PeterO


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[Simh] IS there a BASIC available for DG Nova ?

[Peter Onion]

(Long time lurker here !)

A friend of mine has just building a paper tape reader to read some only tapes 
has has
from his college days in the 1980s.

He says "The machine at college was a Data General Nova and we only had access 
to BASIC!"
so I thought I would ask here if there is anything that might be able to run 
his old
programs again.

Once he's read a tape I'll post a sample here.

PeterO


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