24 Oct
2024
24 Oct
'24
1:10 p.m.
Hi everyone,
Does anyone have the source for the ZRQCxx formatter? I have found a pdf
for ZRQCE0 but am curious if the actual source code for that one, or ZRQCH0
is available? I'd like to make some changes to the UIT table.
-Peter
24 Oct
24 Oct
6:28 p.m.
I don't have the source, but I had great success octal-patching my copy a
few years ago, made it work with a Maxtor xt-11something instead of the
real rd54 / xt-2190.
I'll reply again if I can find the instructions for doing it. Just
followed recipe from some guy's website and it worked perfect.
On Thu, 24 Oct 2024 at 09:20, Peter Ekstrom via cctalk <
cctalk(a)classiccmp.org> wrote:
Hi everyone,
Does anyone have the source for the ZRQCxx formatter? I have found a pdf
for ZRQCE0 but am curious if the actual source code for that one, or ZRQCH0
is available? I'd like to make some changes to the UIT table.
-Peter
9:33 p.m.
Did Lou ever publish somewhere his notes on patching ZRQCH0?
Back from around almost 10 years ago:
https://forum.vcfed.org/index.php?threads/patching-zrqch0-to-use-any-geomet…
Is Lou still around? Looks like he hasn't posted on VCFed in a few years.
On Thu, Oct 24, 2024 at 11:45 AM Jacob Ritorto via cctalk
<cctalk(a)classiccmp.org> wrote:
I don't have the source, but I had great success octal-patching my copy a
few years ago, made it work with a Maxtor xt-11something instead of the
real rd54 / xt-2190.
I'll reply again if I can find the instructions for doing it. Just
followed recipe from some guy's website and it worked perfect.
On Thu, 24 Oct 2024 at 09:20, Peter Ekstrom via cctalk <
cctalk(a)classiccmp.org> wrote:
> Hi everyone,
>
> Does anyone have the source for the ZRQCxx formatter? I have found a pdf
> for ZRQCE0 but am curious if the actual source code for that one, or ZRQCH0
> is available? I'd like to make some changes to the UIT table.
>
> -Peter
>
25 Oct
25 Oct
9:40 p.m.
Search the list back in late 2018, there is a thread with the same subject.
There is a link to a spreadsheet in that thread that has the calculations
for new drive sizes.
Lou and I sort of worked out the details without knowledge of each other
and he had a nice document describing how to create a new entry in the
table. He seemed reluctant to share it at the time, so I will respect that
now.
I was interested in modifying the tables so that I could create a maximum
sized disk to use with an MFM disk emulator.
Congratulations if you have an MFM drive that you think is reliable enough
today to format and try to use. The central theme of the RQDX3 format is
bad block replacement, and you will probably need it.
Based on the reliability of the drive, a portion of the drive is allocated
to bad block replacement. One sector per track (?) is reserved for in-track
replacement and a group of tracks are allocated for out-of-track
replacement. The space allotted for replacements is inconsistent, for
example the RD51 has room for 0.66% of the blocks to fail vs. the RD33
which can only tolerate 0.19% block failure rate. The replacement block
locations are based on a hash. The only place I have seen the replacement
algorithm documented is in an Ultrix driver for the microVAX 2000 (?). This
would make a sector image of an RQDX3 drive very difficult to work with
unless it is connected to another RQDX3 or the replacement map is
understood.
Is Lou around? I hope so, he refined a PDP-8/e memory board design I did
and built multiple copies. That phrase used to imply moving on to some
other hobby, but lately these old computer lists it's become past on. Ugh.
-chuck
If the original author is no longer available to ask I can contribute my
copy to bitsavers. This has been a topic of discussion for many years. I
doubt DEC/Compaq/HP cares anymore.
On Thu, Oct 24, 2024 at 5:34 PM Glen Slick via cctalk <cctalk(a)classiccmp.org>
wrote:
Did Lou ever publish somewhere his notes on patching
ZRQCH0?
Back from around almost 10 years ago:
https://forum.vcfed.org/index.php?threads/patching-zrqch0-to-use-any-geomet…
Is Lou still around? Looks like he hasn't posted on VCFed in a few years.
On Thu, Oct 24, 2024 at 11:45 AM Jacob Ritorto via cctalk
<cctalk(a)classiccmp.org> wrote:
I don't have the source, but I had great success octal-patching my copy a
few years ago, made it work with a Maxtor xt-11something instead of the
real rd54 / xt-2190.
I'll reply again if I can find the instructions for doing it. Just
followed recipe from some guy's website and it worked perfect.
On Thu, 24 Oct 2024 at 09:20, Peter Ekstrom via cctalk <
cctalk(a)classiccmp.org> wrote:
> Hi everyone,
>
> Does anyone have the source for the ZRQCxx formatter? I have found a
pdf
> for ZRQCE0 but am curious if the actual
source code for that one, or
ZRQCH0
> is available? I'd like to make some
changes to the UIT table.
>
> -Peter
>
27 Oct
27 Oct
1:32 p.m.
Hi Chuck,
Lou did reach out to me and shared a copy of his document. (If you read
this Lou, thank you!) I haven't yet, but I plan to go through it and learn
(I know I will) lots of good stuff. I did come across the thread you
mention with your spreadsheet and I also plan to make good use of it. Thank
you for sharing it in that thread!
I have an RD32 drive that has been working fine, but recently developed
some sort of problem that now prevents me from even formatting it.
It starts out just fine, encounters a couple of bad blocks and then stalls
the formatting process. I have another drive that isn't DEC standard so
that's where patching of ZRQCH0 on my XXDP tape comes into place. I'm
guessing you're right, I may have to abandon the idea of using the
real drives and get something like a Qbone or something. Is there such a
thing as an MFM drive emulator that would plug in to the RQDX3 as
a real drive would?
Back in the 80's I came close to getting an 11/23 with a couple of RL02
drives and I think some RX-drives as well. Probably a tape drive too. But
unfortunately it fell through. So this is an attempt to get to tinker with
the real thing. I love the SIMH simulator suite but for some reason, missing
the hardware takes away a big part of tinkering for me. So I am enjoying
having these 11/23+ boards and drives to tinker with now.
Thank you for all the information, tips and pointers!
-Peter
On Sun, Oct 27, 2024 at 1:55 AM Charles Dickman via cctalk <
cctalk(a)classiccmp.org> wrote:
Search the list back in late 2018, there is a thread
with the same subject.
There is a link to a spreadsheet in that thread that has the calculations
for new drive sizes.
Lou and I sort of worked out the details without knowledge of each other
and he had a nice document describing how to create a new entry in the
table. He seemed reluctant to share it at the time, so I will respect that
now.
I was interested in modifying the tables so that I could create a maximum
sized disk to use with an MFM disk emulator.
Congratulations if you have an MFM drive that you think is reliable enough
today to format and try to use. The central theme of the RQDX3 format is
bad block replacement, and you will probably need it.
Based on the reliability of the drive, a portion of the drive is allocated
to bad block replacement. One sector per track (?) is reserved for in-track
replacement and a group of tracks are allocated for out-of-track
replacement. The space allotted for replacements is inconsistent, for
example the RD51 has room for 0.66% of the blocks to fail vs. the RD33
which can only tolerate 0.19% block failure rate. The replacement block
locations are based on a hash. The only place I have seen the replacement
algorithm documented is in an Ultrix driver for the microVAX 2000 (?). This
would make a sector image of an RQDX3 drive very difficult to work with
unless it is connected to another RQDX3 or the replacement map is
understood.
Is Lou around? I hope so, he refined a PDP-8/e memory board design I did
and built multiple copies. That phrase used to imply moving on to some
other hobby, but lately these old computer lists it's become past on. Ugh.
-chuck
If the original author is no longer available to ask I can contribute my
copy to bitsavers. This has been a topic of discussion for many years. I
doubt DEC/Compaq/HP cares anymore.
On Thu, Oct 24, 2024 at 5:34 PM Glen Slick via cctalk <
cctalk(a)classiccmp.org>
wrote:
Did Lou ever publish somewhere his notes on
patching ZRQCH0?
Back from around almost 10 years ago:
https://forum.vcfed.org/index.php?threads/patching-zrqch0-to-use-any-geomet…
Is Lou still around? Looks like he hasn't posted on VCFed in a few years.
On Thu, Oct 24, 2024 at 11:45 AM Jacob Ritorto via cctalk
<cctalk(a)classiccmp.org> wrote:
>
> I don't have the source, but I had great success octal-patching my
copy a
few years
ago, made it work with a Maxtor xt-11something instead of the
real rd54 / xt-2190.
I'll reply again if I can find the instructions for doing it. Just
followed recipe from some guy's website and it worked perfect.
On Thu, 24 Oct 2024 at 09:20, Peter Ekstrom via cctalk <
cctalk(a)classiccmp.org> wrote:
> Hi everyone,
>
> Does anyone have the source for the ZRQCxx formatter? I have found a
pdf
> for ZRQCE0 but am curious if the actual
source code for that one, or
ZRQCH0
> is available? I'd like to make some
changes to the UIT table.
>
> -Peter
>
8:16 p.m.
On Sun, Oct 27, 2024 at 09:32:00AM -0400, Peter Ekstrom wrote:
Is there such a
thing as an MFM drive emulator that would plug in to the RQDX3 as
a real drive would?
Yes.
https://www.pdp8online.com/mfm/
1 Nov
1 Nov
1:28 p.m.
Well, I learned that not all drives that look like ST-506, are... Turns out
the drive I was going to use is a Micropolis 1355, which is an ESDI drive.
So it won't work with the RQDX3.
I guess that drive goes back on the shelf until something else comes along.
Thanks for all the info on the formatter though! I'm sure I'll find
something else down the road I can try that on.
-Peter
On Sun, Oct 27, 2024 at 5:30 PM David Gesswein via cctalk <
cctalk(a)classiccmp.org> wrote:
On Sun, Oct 27, 2024 at 09:32:00AM -0400, Peter
Ekstrom wrote:
Is there such a
thing as an MFM drive emulator that would plug in to the RQDX3 as
a real drive would?
Yes.
https://www.pdp8online.com/mfm/
32
days inactive
40
days old
6 comments
5 participants
participants (5)
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Charles Dickman -
David Gesswein -
Glen Slick -
Jacob Ritorto -
Peter Ekstrom