Burnable, patched Microvax-2000 SCSI-boot EPROM images?
I recently rescued two Microvax-2000s but both have dead RD53s. Does anyone have a ROMable image of the Microvax 2000/Vaxstation 2000 boot-PROM patches from Wolfgang Moeller at http://ftp.gwdg.de/pub/vms/pk2k/ ? I'm looking to install NetBSD, not VMS and I don't have any VMS systems on which to run PATCH. Microvax 2000 specs say it can sustain 3.3MB/s I/O, which has to be via the SCSI interface. So a SCSI emulator should be significantly higher performance than an MFM drive (either 30+ year old drive, or emulator). Web-searching shows a Sean O'Banion has burned the PROMs successfully; I haven't yet found other names. If someone is willing to burn at least one set of EPROMs for me, I'd pay for the service (either ship EPROMS, or pay for them).
RE: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
Do you know what type of ROM/PROM is needed Dave > -Original Message- > From: cctalk On Behalf Of Jonathan Stone > via cctalk > Sent: 20 September 2021 20:02 > To: cctalk@classiccmp.org; port-...@netbsd.org > Subject: Burnable, patched Microvax-2000 SCSI-boot EPROM images? > > I recently rescued two Microvax-2000s but both have dead RD53s. Does > anyone have a ROMable image of the Microvax 2000/Vaxstation 2000 boot- > PROM patches from Wolfgang Moeller > at http://ftp.gwdg.de/pub/vms/pk2k/ ? I'm looking to install NetBSD, not > VMS and I don't have any VMS systems on which to run PATCH. Microvax > 2000 specs say it can sustain 3.3MB/s I/O, which has to be via the SCSI > interface. So a SCSI emulator should be significantly higher performance > than an MFM drive (either 30+ year old drive, or emulator). > > Web-searching shows a Sean O'Banion has burned the PROMs successfully; I > haven't yet found other names. > If someone is willing to burn at least one set of EPROMs for me, I'd pay for > the service (either ship EPROMS, or pay for them). > >
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
A web-page I found over the weekend said M27512-2, but right now i cannot find it. Several sources say 256KB PROM, and the photos show 4 EPROMs, which is consistent with 64Kx8-bit. I have to dash now, more in a few hours. On Monday, September 20, 2021, 02:24:51 PM PDT, wrote: Do you know what type of ROM/PROM is needed Dave > -Original Message- > From: cctalk On Behalf Of Jonathan Stone > via cctalk > Sent: 20 September 2021 20:02 > To: cctalk@classiccmp.org; port-...@netbsd.org > Subject: Burnable, patched Microvax-2000 SCSI-boot EPROM images? > > I recently rescued two Microvax-2000s but both have dead RD53s. Does > anyone have a ROMable image of the Microvax 2000/Vaxstation 2000 boot- > PROM patches from Wolfgang Moeller > at http://ftp.gwdg.de/pub/vms/pk2k/ ? I'm looking to install NetBSD, not > VMS and I don't have any VMS systems on which to run PATCH. Microvax > 2000 specs say it can sustain 3.3MB/s I/O, which has to be via the SCSI > interface. So a SCSI emulator should be significantly higher performance > than an MFM drive (either 30+ year old drive, or emulator). > > Web-searching shows a Sean O'Banion has burned the PROMs successfully; I > haven't yet found other names. > If someone is willing to burn at least one set of EPROMs for me, I'd pay for > the service (either ship EPROMS, or pay for them). > >
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Mon, Sep 20, 2021 at 5:24 PM Dave Wade G4UGM via cctalk wrote: > Do you know what type of ROM/PROM is needed 4x 27512 (32-bit wide image) I have a MicroVAX 2000 but haven't managed to get that SCSI hack working myself. It's been many years since I last fiddled with it. -ethan
RE: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
> -Original Message- > From: Ethan Dicks > Sent: 21 September 2021 06:39 > To: Dave Wade ; General Discussion: On-Topic > and Off-Topic Posts > Cc: Jonathan Stone > Subject: Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images? > > On Mon, Sep 20, 2021 at 5:24 PM Dave Wade G4UGM via cctalk > wrote: > > Do you know what type of ROM/PROM is needed > > 4x 27512 (32-bit wide image) > > I have a MicroVAX 2000 but haven't managed to get that SCSI hack working > myself. > > It's been many years since I last fiddled with it. > > -ethan I am sure some one on here can blow those. I can probably do it. Its been ages since I did any and I am a long way from the programmer for a couple of weeks. I was going to try for my MV2000 but it not at the top of the "to-do" pile. Dave
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
Jonathan Stone via cctalk wrote: > I recently rescued two Microvax-2000s but both have dead RD53s. Does anyone > have a ROMable image of the Microvax 2000/Vaxstation 2000 boot-PROM patches > from Wolfgang Moeller at http://ftp.gwdg.de/pub/vms/pk2k/ ? I'm looking to > install NetBSD, not VMS and I don't have any VMS systems on which to run > PATCH. Microvax 2000 specs say it can sustain 3.3MB/s I/O, which has to be > via the SCSI interface. So a SCSI emulator should be significantly higher > performance than an MFM drive (either 30+ year old drive, or emulator). > > Web-searching shows a Sean O'Banion has burned the PROMs successfully; I > haven't yet found other names. > If someone is willing to burn at least one set of EPROMs for me, I'd pay for > the service (either ship EPROMS, or pay for them). > I've tried this almost 2 years before..and it worked "somewhat". An VS2000 booted up in the first stage but the NetBSD Kernel couldn't mount root since nothing in the loader expected a disk at the NCR SCSI interface on the VS2000. Ragge agreed to look at this (bootcode) on my VS2000, but I'vwe couldn't get an ssh connection from the internet to an VS3100 M76 to which the VS2000 console was connected to..to work.. For yure I could burn the proms, but I think I'm on the other side of the pond.. Regards, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 i...@tsht.de Fax +49 37292 709779 Tel +49 37292 709778 Mobil: 0172 8790 741
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
Jonathan Stone wrote: > > I recently rescued two Microvax-2000s but both have dead RD53s. Does > anyone have a ROMable image of the Microvax 2000/Vaxstation 2000 boot-PROM > patches from Wolfgang Moeller at http://ftp.gwdg.de/pub/vms/pk2k/ ? � > I'm looking to install NetBSD, not VMS and I don't have any VMS systems > on which to run PATCH. Microvax 2000 specs say it can sustain 3.3MB/s > I/O, which has to be via the SCSI interface. So a SCSI emulator should > be significantly higher performance than an MFM drive (either 30+ year > old drive, or emulator). > > Web-searching shows a Sean O'Banion has burned the PROMs successfully; I > haven't yet found other names. > If someone is willing to burn at least one set of EPROMs for me, I'd pay > for the service (either ship EPROMS, or pay for them). > > � > I can probably burn a set of EPROMS. You don't say where you are but if "kiwi" in your email address is a hint, you are probably on nearly the exact opposite side of the planet from where I am (Ireland). If you want me to have a try, please send me eight 27256s, four for your microvax and four for mine. That will help cover the cost of the return postage for your four. If you want to try other options, maybe you could put some minimal boot code on a MOP server and have your MV2000 boot from that over the network before it tries to access your SCSI disk? Or put some code on a floppy disk and boot from that? If you have a suitable adapter cable, you can plug a 5.25in HD floppy drive into your MV2000 provided it can be jumpered suitably to look line an RX33. My experience with random PC drives says some can and some can't. A 3.5in drive can also be used but the ROMs are expecting an RX33 so an RX33 disk image should be written to the 3.5in floppy. Regards, Peter Coghlan.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
He could also just fix the RD53 and boot off that, then transfer to the much faster SCSI. I still keep the RX02's around on my pdp11 because I can boot BRU64k for tape backups. It works. :-) On 9/21/2021 10:39 AM, Peter Coghlan via cctalk wrote: If you want to try other options, maybe you could put some minimal boot code on a MOP server and have your MV2000 boot from that over the network before it tries to access your SCSI disk? Or put some code on a floppy disk and boot from that? If you have a suitable adapter cable, you can plug a 5.25in HD floppy drive into your MV2000 provided it can be jumpered suitably to look line an RX33. My experience with random PC drives says some can and some can't. A 3.5in drive can also be used but the ROMs are expecting an RX33 so an RX33 disk image should be written to the 3.5in floppy. Regards, Peter Coghlan.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ year old rotating media. If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the obvious performance reasons. Reseller price for a Maxtor XT-2190 (RD54) is just over US $1000. Disk Emulators are significantly cheaper. Thirty years ago I did 4.3BSD-Tahoe kernel hacking on a Vaxstation-II/RC with two RD53s. One of the spindles was very noisy, I think from the bearing. I really like the quiet of scsi2sd in my DECstation 5000s (and soon, Alpha 3000/500s and a /700). One of the reasons I got the 2000s is to format MFM drives for an RQDX3 (I don't have any PDP-11 CPUs). I have a CMD CQD-420 Qbus SCSi controller, and an MTI almost-equivalent. I've seen Glen Slick's reverse engineering of the PLD for the CDQ-200. I hope the newer MTI board "just works"; but if not, MFM is a fallback. On Tuesday, September 21, 2021, 08:44:11 AM PDT, Chris Zach via cctalk wrote: He could also just fix the RD53 and boot off that, then transfer to the much faster SCSI. I still keep the RX02's around on my pdp11 because I can boot BRU64k for tape backups. It works. :-) On 9/21/2021 10:39 AM, Peter Coghlan via cctalk wrote: > If you want to try other options, maybe you could put some minimal boot > code on a MOP server and have your MV2000 boot from that over the network > before it tries to access your SCSI disk? Or put some code on a floppy disk > and boot from that? If you have a suitable adapter cable, you can plug a > 5.25in HD floppy drive into your MV2000 provided it can be jumpered suitably > to look line an RX33. My experience with random PC drives says some can > and some can't. A 3.5in drive can also be used but the ROMs are expecting > an RX33 so an RX33 disk image should be written to the 3.5in floppy. > > Regards, > Peter Coghlan.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
> On Sep 21, 2021, at 12:00 PM, Jonathan Stone via cctalk > wrote: > > The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ year > old rotating media. > If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the > obvious performance reasons. Emulators presumably act, performance wise, like SSDs. Given that, an MFM emulator will significantly outperform a SCSI hard drive since it has no seek delays. David Gesswein's MFM emulator works impressively well and is inexpensive, too. paul
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On 9/21/2021 12:00 PM, Jonathan Stone wrote: The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ year old rotating media. If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the obvious performance reasons. Been thinking about that: I'm tempted to open one of these RD53's, leave it open for an hour or two, then seal it up and run it till it explodes. The RD53 includes an internal filter between the top of the disk platter (where the internal fan exhausts) and a pipe to the spot where the heads are. That filter has always been quite clean, I'm guessing dust and such from the modern house would just get caught in that with no further issues. I'll put that on my "to do" pile. My main 11 runs with an MTI ESDI controller and a CDC 383mb half height drive. No issues at all with that generation of disk, it just purrs after sitting for 15 or so years. Same with the Hitachi 150mb drive. ESDI is pretty quick, enough for what I need these days. C
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tue, Sep 21, 2021 at 9:00 AM Jonathan Stone via cctalk wrote: > > One of the reasons I got the 2000s is to format MFM drives for an RQDX3 (I > don't have any PDP-11 CPUs). I have a CMD CQD-420 Qbus SCSi controller, and > an MTI almost-equivalent. I've seen Glen Slick's reverse engineering of the > PLD for the CDQ-200. I hope the newer MTI board "just works"; but if not, MFM > is a fallback. The MTI QTS-30 board I have is essentially the same thing as a CMD CQD-200 board, just with different firmware. It can be converted into a CQD-200/TM functional equivalent by swapping the firmware EPROMs and CSR decode PAL. I haven't seen an MTI version of the CMD CQD-420 board. The CQD-420 is more similar to the CQD-220A than the CQD-220, with the standard CSR address decoding being done in the QBC0420 ASIC instead of in the PAL. The CQD-220A / CQD-420 PALs only decode the "special" disk/tape CSR address when that is selected via the address selection DIP switches.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tuesday, September 21, 2021, 09:15:20 AM PDT, Paul Koning via cctalk wrote: >> On Sep 21, 2021, at 12:00 PM, Jonathan Stone via cctalk >> wrote: >> >> The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ >> year old rotating media. >> If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the >> obvious performance reasons. > > >Emulators presumably act, performance wise, like SSDs. Given that, an MFM >emulator will significantly outperform a SCSI hard >drive since it has no seek >delays. > >David Gesswein's MFM emulator works impressively well and is inexpensive, too. My comparison was MFM emulators versus SCSI emulators. scs2sd is significantly cheaper than David Gesswein's MFM emulator; and higher performance. (IIRC, Gesswein's emulator transfers entire track images between SSD and RAM, but I may be remembering DREM documentation instead.). OTOH, for a machine which already has an MFM controller but no SCSI, an MFM emulator is cheaper than scs2sd plus SCSI controller. (At least for Qbus. At eBay prices, even RQDX3 plus distribution panel plus emulator, is cheaper than bootable SCSI controller plus SCSI emulator). SCSI performance will still be better.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On 21/09/2021 18:38, Jonathan Stone via cctalk wrote: (At least for Qbus. At eBay prices, even RQDX3 plus distribution panel plus emulator, is cheaper than bootable SCSI controller plus SCSI emulator). SCSI performance will still be better. My recollection is that the MicroVAX 2000 SCSI isn't complete and was only intended for the tape unit. Whether its performance beats an RD54 will be interesting to see. Antonio -- Antonio Carlini anto...@acarlini.com
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tuesday, September 21, 2021, 11:02:38 AM PDT, Antonio Carlini via cctalk wrote: > My recollection is that the MicroVAX 2000 SCSI isn't complete and was > only intended for the tape unit. Whether its performance beats an RD54 > will be interesting to see. The ROM/VMB support certainly isn't "complete". The NCR5380 itself can do SCSI for both disks and tapes. My comparison point would probably be MFM emulator versus SCSI2SD v5.2. Documentation, http://bitsavers.trailing-edge.com/components/ncr_symbios/scsi/NCR_SCSI_Engineering_Notebook_Rev2_Oct85.pdf , says the NCR538x didn't support synchronous SCSI until the 5386S. The SCSI devices would have to avoid ID 0, as that's what the MV2000 ROM uses.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tuesday, September 21, 2021, 05:39:23 AM PDT, Holm Tiffe via cctalk wrote: >I've tried this almost 2 years before..and it worked "somewhat". >An VS2000 booted up in the first stage but the NetBSD Kernel couldn't >mount root since nothing in the loader expected a disk at the NCR SCSI >interface on the VS2000. Ragge agreed to look at this (bootcode) on my >VS2000, but I'vwe couldn't get an ssh connection from the internet to >an VS3100 M76 to which the VS2000 console was connected to..to work.. I once "owned" the NetBSD MIPS port, and I've done VAX assembly and kernel code j(e.g., VMS device drivers). If I can't figure it out by comparison to 3100 code, I'll contact Ragge and set up remote access via a BCC08, a NetBSD laptop, and serial. (At least one of the VS200s is jumpered to Vaxstation mode, and I have two GPX daughter-cards on order.) >For yure I could burn the proms, but I think I'm on the other side of >the pond.. I am located in the San Francisco Bay Area. I came here for grad school and never left. It may be time for me to buy a PROM programmer. Anyone got recommendations for a budget device? "Amazon's choice" is https://www.amazon.com/dp/B082D5NQ2P. The costlier option includes 10 different sockets, and it claims support for 29xxx and 29Cxxx EPROMs, plus lots of others. The DEC-badged Data-IO " on eBay is tempting, but expensive, and I don't know where to find software.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
> The DEC-badged Data-IO " on eBay is tempting, but expensive, and I don't know > where to find software. If it is just a regular Data I/O underneath, head over to the groups.io page: https://groups.io/g/DataioEPROM/ Thanks, Jonathan
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tuesday, September 21, 2021, 01:37:28 PM PDT, Jonathan Chapman wrote: >> The DEC-badged Data-IO " on eBay is tempting, but expensive, and I don't >> know where to find software. >If it is just a regular Data I/O underneath, head over to the groups.io page: > >https://groups.io/g/DataioEPROM/ The eBay listing is https://www.ebay.com/itm/303208951366. Nostalgic though it is, I'd prefer to put the price difference into vintage computers, rather than vintage PROM programmers.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tue, Sep 21, 2021 at 4:37 PM Jonathan Chapman via cctalk wrote: > > The DEC-badged Data-IO " on eBay is tempting, but expensive, and I don't > > know where to find software. > > If it is just a regular Data I/O underneath, head over to the groups.io page: > > https://groups.io/g/DataioEPROM/ One of my Fall projects is to figure out why my Data I/O 29A isn't working. It's been sitting for years and when I got it out last year, it didn't pass self-test. I need to spend some time looking over the posts in that group to see if my symptoms are common. That said, unless you need to program stuff other than 2716-27512 and up in that line, an old Data I/O is probably not what you need. If you need to program chips made before 1985, then it might be a good choice. -ethan
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
> One of my Fall projects is to figure out why my Data I/O 29A isn't > working. It's been sitting for years and when I got it out last year, > it didn't pass self-test. I need to spend some time looking over the > posts in that group to see if my symptoms are common. The diagnostics are pretty good, and the service manual for the base + pack of choice will get you through it! Let me know if you can't get it going. > That said, unless you need to program stuff other than 2716-27512 and > up in that line, an old Data I/O is probably not what you need. If > you need to program chips made before 1985, then it might be a good > choice. Agreed, not necessary to go with a Data I/O if you don't need to program old or weird stuff. And certainly not at the price of that eBay one, with the limited pack it has, and no front panel/display. Thanks, Jonathan
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?]
..the compatible Device for the Labtool-48 is the Dataman-48, Software is here: https://www.dataman.com/dataman-4848lv-resources Regards, Holm - Forwarded message from Holm Tiffe - Date: Wed, 22 Sep 2021 07:45:32 +0200 From: Holm Tiffe To: Jonathan Stone Subject: Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images? Ok..sounds good so far.. I have an Labtool-48 Programmer for example..thats an old Promer with an parallelport. Software is available for an OEM Device and I'm using that. Forgot in the moment what this was..but I can check that later. There are at least 3 Versions of the Promer that are more or less incompatible to the others, there are "upgrades", with other PCBs in there..last variant is able to do USB.. I'm owning the "plain" variant. Another from my stuff is an HiLo ALL07, and I have German made GALEP III and GALEP IV. All with Centronics Interface.. good Promers. I think it is ok to have old programmers (and old programmer-conterollers (old Laptops)) dedicated to them. I never had to program 3,3V Eproms an such things.. every time old Devices like Eproms, GALS or even TTL ROMs. 82S100 too.. I'm a german.. and sending Eproms from here seems to be the worst case to me... Regards, Holm A A A A A A A A Jonathan Stone wrote: > > > On Tuesday, September 21, 2021, 05:39:23 AM PDT, Holm Tiffe via cctalk > wrote: > > >I've tried this almost 2 years before..and it worked "somewhat". > >An VS2000 booted up in the first stage but the NetBSD Kernel couldn't > >mount root since nothing in the loader expected a disk at the NCR SCSI > >interface on the VS2000. Ragge agreed to look at this (bootcode) on my > >VS2000, but I'vwe couldn't get an ssh connection from the internet to > >an VS3100 M76 to which the VS2000 console was connected to..to work.. > > I once "owned" the NetBSD MIPS port, and I've done VAX assembly and kernel > code j(e.g., VMS device drivers). If I can't figure it out by comparison to > 3100 code, I'll contact Ragge and set up remote access via a BCC08, a NetBSD > laptop, and serial. (At least one of the VS200s is jumpered to Vaxstation > mode, and I have two GPX daughter-cards on order.) > > >For yure I could burn the proms, but I think I'm on the other side of > >the pond.. > > I am located in the San Francisco Bay Area. I came here for grad school and > never left. > > It may be time for me to buy a PROM programmer. Anyone got recommendations > for a budget device? "Amazon's choice" is > https://www.amazon.com/dp/B082D5NQ2P. The costlier option includes 10 > different sockets, and it claims support for 29xxx and 29Cxxx EPROMs, plus > lots of others. > > The DEC-badged Data-IO " on eBay is tempting, but expensive, and I don't know > where to find software. -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 i...@tsht.de Fax +49 37292 709779 Tel +49 37292 709778 Mobil: 0172 8790 741 - End forwarded message - -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 i...@tsht.de Fax +49 37292 709779 Tel +49 37292 709778 Mobil: 0172 8790 741
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
On Tue, Sep 21, 2021 at 12:15:12PM -0400, Paul Koning wrote: > > On Sep 21, 2021, at 12:00 PM, Jonathan Stone via cctalk > > wrote: > > > > The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ > > year old rotating media. > > If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the > > obvious performance reasons. > > Emulators presumably act, performance wise, like SSDs. Given that, an MFM > emulator will significantly outperform a SCSI hard drive since it has no seek > delays. > > David Gesswein's MFM emulator works impressively well and is inexpensive, too. > The MFM emulator can't transfer data faster than the 5 Mbit/second, 625k Byte/sec of the ST-506 standard. Seek time isn't zero due to overhead in moving the data in the Beaglebone to where the PRU processors can access it. Think its around 0.6ms/head. An entire cylinder is transfered on each seek. Additional time if cylinder was written to. Each track written needs to be moved also. Most ST-506 drives are slower. I'm faster than average seek for RD54 but it wins for single track seek at 4ms with 15 heads.
Re: Burnable, patched Microvax-2000 SCSI-boot EPROM images?
I just purchased an RK05 Controller for my PDP-8/E, does this emulator work to emulate RK05 packs? If it does then maybe I can use it as mass storage until i can find an RK05 (or Plessey or Diablo clones) . Thanks... On 9/24/2021 3:19 PM, David Gesswein via cctalk wrote: On Tue, Sep 21, 2021 at 12:15:12PM -0400, Paul Koning wrote: On Sep 21, 2021, at 12:00 PM, Jonathan Stone via cctalk wrote: The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ year old rotating media. If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the obvious performance reasons. Emulators presumably act, performance wise, like SSDs. Given that, an MFM emulator will significantly outperform a SCSI hard drive since it has no seek delays. David Gesswein's MFM emulator works impressively well and is inexpensive, too. The MFM emulator can't transfer data faster than the 5 Mbit/second, 625k Byte/sec of the ST-506 standard. Seek time isn't zero due to overhead in moving the data in the Beaglebone to where the PRU processors can access it. Think its around 0.6ms/head. An entire cylinder is transfered on each seek. Additional time if cylinder was written to. Each track written needs to be moved also. Most ST-506 drives are slower. I'm faster than average seek for RD54 but it wins for single track seek at 4ms with 15 heads.