RL01/RL02 bad sector file structure

[PDP11GY]

Hello @ all

Concerning my RL02(1) Simulator project, I am hanging araound again
because I have no idea how I can reconstruct/simulate the bad sector file
based on a SD card in my project. No exact upgrade info is available, only some notes
in the RL02 technical manual on page 49, figure 2-9.
If you have access to detailed information concerning the structure of
the bad sector file format, please let me know this.
At least if you have access to the RT-11 DL driver sources and/or the dup.sav program
it would be also very helpful

Just for info, some update info concerning my project:
Version V0:
This version has been given up, because: Usage of the SD card
A SD card is a flash memory device with 512 Bytes/block. Also, each 512 block of data on a SD card can
be written a limited number of times ( depending on the SD card used, this number varies between 1000
and 2000 times ). Running an old operating system ( RSX11-M ) from the SD card via my simulator would
destroy every SD card after some hours because this old operating systems are very I/O intensive.
Another disadvantage was the SD card tranfer rate. A simulated seek would always result to write(save)
back one complete cylinder ( 40960 byte, 80 blocks ) to the SD card and read in the new cylinder.
Result: Poor performance and timeouts.

Version V1: Bad sector file issue is open
With reference to the disadvantages of version V.0, this version is a RL01(!) simulator only.
Description: Hardware based simulator for DEC RL01 disk drives which is based on the Altera
DE1 development-board. This cost-effective board is based on the Cyclone II EB2C20F484C7
FPGA, which has 2 disadvantage:
1) the limitation of only 52 4K memory blocks. This limitation means, that only one simulated
disk track can be holded in FPGA-Dual-Ported-RAM (DPR) memory.
2) The size of the 8MB SD-RAM onboard memory is to small to hold a RL02 image in memory.
( Follow up projects will be based on the DE0 Nano board with 32MB RAM)

Many thanks in advance, Reinhard

 

[RSX11M+]

...Concerning my RL02(1) Simulator project, I am hanging araound again
because I have no idea how I can reconstruct/simulate the bad sector file
based on a SD card in my project. No exact upgrade info is available, only some notes
in the RL02 technical manual on page 49, figure 2-9.
If you have access to detailed information concerning the structure of
the bad sector file format, please let me know this.
At least if you have access to the RT-11 DL driver sources and/or the dup.sav program
it would be also very helpful...

Hello Reinhard, seems you've made quite a bit of progress since we last talked.


I think you must be referring to the rather scant explanation in the RL02TechDescr.pdf. [That document looks incomplete to me]


Curiously, there is a slightly better one in the RL01/02 User Guide EK-RL012-UG-005 and although it includes the same Figure you referenced above, the explanation on the preceding page in this manual is much clearer.

I recall that the duplicated copies of the bad sector information are intended as a hedge against bad sectors in the bad sector area. The precise usage of this feature is explained somewhere, because I saw it again when I was researching Servo Information last time we corresponded. If it's important, I'll try to find it again for you.

Anyway, let me know if this doesn't help enough.

 

[PDP11GY]

Hello,
thank you very much for your response.
However your upgrade infos do not help me along much, though.
If you have plenty of time, would be great if you can find
the additional Bad-Sector Servo Information.
In the meantime I am able to collect data from a connected
RL02 disk drive ... but you can imagine this is a lot of
additional work. And a second problem is, my RL02 disk drive
run in fault state at some times.
Regards, Reinhard

 

[RSX11M+]

I have located the program listing for CZRLMB0 on microfiche. This is an XXDP utility to perform RL01 & RL02 media maintenance including scanning media for bad sectors, and managing the Bad Sector File contents. This also appears to include re-initializing the manufacturer's bad sector area if it should be unreadable or invalid.

That's the good news... the bad news is: It's almost 120 pages long and will take me weeks to scan and convert to a format I can post.

So let me ask you this... can you explain to me what is unclear or contradictory in the documentation we already have?

Are you able to read the Bad Sector Area on your real RL?
does it appear to contain invalid data?

Can you give me something to focus my search on to perhaps allow me to send you code snippets that are meaningful without having to make you wait for the entire listing? [which may not be of help to you once I do]

 

[RSX11M+]

Have you seen this DEC STD 144 document?

[B]DEC STD 144             COMPANY CONFIDENTIAL[/B]




        TITLE:  Disk Standard for Recording and Handling Manufacturing
                Detected Bad Sectors

     ABSTRACT:  This standard is both a hardware and a software standard.
                It specifies the hardware disk format, controller require-
                ments and software handling of manufacturing site deter-
                mined bad sectors of the RK06 and RK07 data cartridges
                and future disks.  Conformance to this standard will result
                in improving reliability for the combined hardware/software
                system as experienced by our customers.

                This standard defines the format used at the manufacturing
                site to record the locations of sectors containing disk
                surface errors.  The highest numbered track of the car-
                tridge is used to record track, cylinder, and sector loc-
                ation of the error in both 20 and 22 sector format.  Pro-
                vision is also made for recording serial numbers and other
                pertinent manufacturing information.  In addition, errors
                found at the time of manufacture and errors found in subse-
                quent field use are indicated by means of good sector flags
                in word 2 of the header.  This standard specifies two
                operating system techniques for handling these bad regions:
                one for small systems and one for large systems.  Both
                techniques prevent the user from using bad sectors
                detected at the manufacturing site....

The CZRLMB0 listing indicates it's conformance to this standard for the Bad Sector File of RL media.

 

[PDP11GY]

The information you have provided is sufficient, thank you !
It is not necessary to spend more effort to get the entire listing.
> Are you able to read the Bad Sector Area on your real RL?
Yes with much overhead, I can do it. Writing a program to force a
seek to the last cylinder to collect the data via my MFM decoder
and save the data on SD card. But the RL disk drive is going often
to Fault state and I think it is a media problem.
Anyway, many thanks for all the infos, and if you want, I will inform
you about the progress of my project. Regards, Reinhard

 

[RSX11M+]

Ok Reinhard, good that you found what you need.

I suggest you look into running CZRLM... it may help you get access to your RL's Bad Block File without having to write code yourself.

Good luck, please keep us posted on your progress.