- cctalk - classiccmp.org

by Eric Moore

Hello, I am looking for 3/16ths inch ink ribbon as used on the IBM 029 keypunch. I have one lightly damaged ribbon that is entirely dry. I was told by a typewriter restorationist that ribbon re-inking with nylon never works. Has anyone had much success cleaning and rewetting ink ribbons? The WD40 trick on the internet seems like it would gunk up the punch mechanism. Thanks for any information yall can provide, -Eric

3 years, 1 month

4
5
0 0

RQDX3's: Lessons learned.

by Chris Zach

Some thoughts on this day of working on MFM drives: 1) MFM drives are just going bad. They were always kind of meh in terms of reliability, but I think even since 2019 (the last time I checked these drives) things have gotten worse. Drives which were readable and good then are now either shot or throwing errors and they have had an easy 3+ years in my upstairs room. 2) There are at least two RQDX3 ROM sets. The earlier one does not support the RX33 floppy and doesn't give any info during formatting. The later version (Version 4) does support the RX33 and is a lot nicer. 3) Seagate drives seem to be pretty good, especially the 20mb ones. They have no problems, work well, and are pretty right-sized for an RT11 system. 4) RD53 drives are weird. Their main failure is the drive head positioner just gets stuck and needs to be worked loose. Unfortunately that requires removing the lid. Fortunately there is a good filter in the drive along with an air handler that runs air from inside the drive body through the filter, then into the spindle where it is blown over the heads. Result is a pretty clean drive on the inside and so far opening the lid doesn't seem to be a recipe for instant destruction. Go figure. I may try an RD53 in one of my Pro/380's. It's about time I loaded up the final version of P/OS, as I can use the Gotek floppy to load everything instead of screwing with the RX50's. Or can I do that and switch disks on the fly with a single Gotek... Hm. 5) For anything bigger, it's time to retire the MFM drives. Unlike RL02's these things just were not that reliable when new and at this point are kind of falling apart. I have not had any trouble with the ESDI disks, but it might just be a matter of time. Perhaps I should look into duplexing my 330mb CDC drive in the 11/84.... CZ

3 years, 1 month

7
8
0 0

After more than three years, U of Iowa's PDP-8 project active again

by William Sudbrink

After more than three years, U of Iowa's PDP-8 project active again -- This email has been checked for viruses by Avast antivirus software. www.avast.com

3 years, 1 month

8
9
0 0

Q-BUS Boards available

by David Coolbear

I have the following Q-BUS boards available. M7168 VCB02, QDSS Q 4-plane colour bitmap module M7169 VCB02, QDSS Q 4-plane video controller module M7608 MS630 RAM for KA630 M7608 MS630 RAM for KA630 M7606 KA630 Microvax II CPU M7620 KA650 Q MicroVAX III CPU M7165 Qbus SDI disk adapter I also have a Smoke Signal Broadcasting, dual 8" floppy set and a SS50 bus controller for the same. All are available for pick-up in Queen Creek, AZ, USA. If there's no interest, all will go to recycling.

3 years, 1 month

4
3
0 0

Formatting and using RQDX3's and 2190's.

by Chris Zach

Decided to spend some time working on my 11/73 with MFM drives. Currently it has one of my RQDX3 boards (I have 3, 1 in attic), a 40mb ST412 drive (the half height Seagate whatever) which works fine. No issues there. I'm trying to format an RD54 compatible drive and am running into major issues. First, my two RWDX3's have different ROM dates, the old one is 1986 and the new one is 1990. This is important because I can't boot RX33 disk images with my GoTek using the old card but I can using the new one. Question: I'm guessing the old ROMs only supported RX50 disks? Or is it a secret jumper setting. Anyway I do have both RX33 and RX50 versions of XXDP so not a big issue. On to formatting. The old controller (which I used for the 40mb Seagate) had pins 2-3 jumpered on W23. With that the RD54 was able to autoformat but then would crash xxdp as soon as the initial format was done. Odd. So I used the new controller with 1-2 and 3-4 jumpered. Same problem. Then I tried having 1-2 jumpered and did a manual format (not autoformat, select RD54, etc) I noticed that on the old board it would ask me for the date when doing this kind of format, on the new board it would just ask me for the serial number. Odd. Question: Is the ZRQCH0.BIN file calling different routines in the RQDX3 ROM? Anyway after this the drive would format but then do endless seek errors on the "read" portion of the disk check. Two drives did this, so it's probably not the drives. Odd. Putting the drives on the Dave Gesswin MFM reader showed all cylinders could be read. Question: Can Dave G's board be used to low level format an RD54? Can it test physical disk for errors (wasn't sure) Now the drives only format for a minute or two before throwing errors. Looks like something is very confused on XXDP. Not going to try any other disks until I figure this out. Thoughts? Different sites say different things about the RQDX3 jumpers, some say to jumper 2-3 to allow more than 7 heads, some say to jumper pins 1-2 and some say jumper pins 1-2 on "early ROM" and 1-2 3-4 on "later ROM". This is a serious pain, but just what settings should be done to allow low level formatting, and did my previous attempts to low level wedge these disks from the RQDX3 point of view? Can I do a low level wipe with Dave Gesswin's board/software? Thanks! Chris

3 years, 1 month

5
9
0 0

Re: ST512 [WAS:RE: Re: Nuking an MFM drive with a magnet, format/servo gone?]

by Tom Gardner

The ST512 was a thin-film head version of the ST506, per Seagate : "This increased capacity is accomplished by using the inner portion of the disc surface that was previously unused and by increasing the disc track density from 255 tracks per inch to 270 tracks per inch To reliably use the inner portion of the disc. The ST512 uses a new type of read/write head - a "thin film" head." It was dropped in 1981 due to the lack of a reliable supply of heads and replaced by the ST412. -----Original Message----- From: Tony Duell [mailto:ard.p850ug1@gmail.com] Sent: Friday, February 03, 2023 9:27 AM To: Alexandre Souza Cc: General Discussion: On-Topic and Off-Topic Posts Subject: [cctalk] Re: Nuking an MFM drive with a magnet, format/servo gone? On Fri, Feb 3, 2023 at 5:21 PM Alexandre Souza <alexandre.tabajara(a)gmail.com> wrote: > > I thoug the right one was st512...can you enlighten me on this subject Tony? I've never heard it called that. It's often called 'ST506' but that drive had a few differences from the later ones. it didn't support buffered seeks AFAIK. The ST412 did and was the most common of a family of 3 similar drives (ST406, ST412, ST419) so it tends to be used as the de-facto name of the interface. -tony

3 years, 1 month

1
0
0 0

Formatting and using RQDX3's and 2190's.

by Chris Zach

Decided to spend some time working on my 11/73 with MFM drives. Currently it has one of my RQDX3 boards (I have 3, 1 in attic), a 40mb ST412 drive (the half height Seagate whatever) which works fine. No issues there. I'm trying to format an RD54 compatible drive and am running into major issues. First, my two RWDX3's have different ROM dates, the old one is 1986 and the new one is 1990. This is important because I can't boot RX33 disk images with my GoTek using the old card but I can using the new one. Question: I'm guessing the old ROMs only supported RX50 disks? Or is it a secret jumper setting. Anyway I do have both RX33 and RX50 versions of XXDP so not a big issue. On to formatting. The old controller (which I used for the 40mb Seagate) had pins 2-3 jumpered on W23. With that the RD54 was able to autoformat but then would crash xxdp as soon as the initial format was done. Odd. So I used the new controller with 1-2 and 3-4 jumpered. Same problem. Then I tried having 1-2 jumpered and did a manual format (not autoformat, select RD54, etc) I noticed that on the old board it would ask me for the date when doing this kind of format, on the new board it would just ask me for the serial number. Odd. Question: Is the ZRQCH0.BIN file calling different routines in the RQDX3 ROM? Anyway after this the drive would format but then do endless seek errors on the "read" portion of the disk check. Two drives did this, so it's probably not the drives. Odd. Putting the drives on the Dave Gesswin MFM reader showed all cylinders could be read. Question: Can Dave G's board be used to low level format an RD54? Can it test physical disk for errors (wasn't sure) Now the drives only format for a minute or two before throwing errors. Looks like something is very confused on XXDP. Not going to try any other disks until I figure this out. Thoughts? Different sites say different things about the RQDX3 jumpers, some say to jumper 2-3 to allow more than 7 heads, some say to jumper pins 1-2 and some say jumper pins 1-2 on "early ROM" and 1-2 3-4 on "later ROM". This is a serious pain, but just what settings should be done to allow low level formatting, and did my previous attempts to low level wedge these disks from the RQDX3 point of view? Can I do a low level wipe with Dave Gesswin's board/software? Thanks! Chris

3 years, 1 month

1
0
0 0

ZFS, was [... GreaseWeazle ..]

by emanuel stiebler

On 2023-02-02 04:38, David Brownlee wrote: > That reminds me (looks at 43.5T of zfs pool that has not had a scrub > since 2021). > > It can be nice to have a filesystem which handles redundancy and also > the option to occasionally read all the data, check end to end > checksums (in the unlikely case a device returns a successful read > with bad data), and fixup everything. Does not eliminate the need for > remote copies, but gives a little extra confidence that the master > copy is still what it should be :) So, what else do you guys use, to make sure your data is safe for the years to come?

3 years, 1 month

12
13
0 0

CD-R, DVD-R media available

by David Barto

100’s of CD-R, Sony, TDK, and FujiFilm. 25-30 DVD-R Sony and TDK And CD cases sufficient to hold all the disks Heavy, available for the cost of shipping. I’m in San Diego, so local delivery is possible. David

3 years, 1 month

5
4
0 0

1975 Homebrew Computer Club Newsletter

by Tarek Hoteit

One website has an archive of the first Homebrew Computer Club newsletters. The newsletter is associated with the Homebrew club that kicked off the personal computer revolution https://arkive.net/gallery/homebrew-computer-club Regards, Tarek Hoteit

3 years, 1 month

3
2
0 0

2026

2025

2024

2023

2022

cctalk