test-drb April 2007

test-drb@ccmp.vtda.org

257 participants
560 discussions

MFMulation? (Solid-state replacements for MFM drives)

by entity＠nenevr.demon.co.uk

Hello, all. Does anyone on the list know if anyone in our extended community has ever come up with some sort of plug-compatible flash memory replacement for MFM drives? I've a vague idea that I've seen a commercial offering at some point in the past, but obviously that'd be a fairly expensive move to make. (Fairly? Oh, OK. Very.) I've got a Northstar Horizon that I mentioned on here many, many years ago and I've just started looking at it again; once I've got it up and running it'd be nice to add some sort of permanent storage, but without jettisoning one of the floppy drives. The SuperIO board is one option, but I'd like to keep it as stock-Northstar as I can. Anyway, I'd be interested to hear any thoughts on the topic! Cheers, Simon.

17 years, 9 months

MFMulation? (Solid-state replacements for MFM drives)

by ajp166＠bellatlantic.net

> >Subject: Re: MFMulation? (Solid-state replacements for MFM drives) > From: Jules Richardson <julesrichardsonuk at yahoo.co.uk> > Date: Mon, 16 Apr 2007 06:56:56 -0500 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >Chuck Guzis wrote: >> On 15 Apr 2007 at 19:36, David Comley wrote: >> >>> Exactly. My intended uses are primarily VAX/VMS-based. >> >> Since, as in floppies, you're dealing with raw (unseparated ) data at >> 5MHz or thereabouts, recording bit transitions is out of the >> question. So you'd need some circuitry to both interpret and to >> synthesize not only bits but the various address headers and CRCs. >> IIRC, there wasn't a huge amount of interchangeability between the >> various controller vendors, so you'd need several (selectable) >> routines to handle that. Then there's the matter of RLL and ARLL-- >> and synthesizing CRC or ECC results. > >I'm not sure - remember the task is to emulate a drive, not a controller. >Isn't an MFM ST506/412 drive just a bucket of rotating bits and a track stepper? > >Or does the index pulse function more like that of a hard-sectored floppy - >i.e. the number of sectors per track is fixed in hardware, and there's an >index pulse at the start of each sector? Index is once per revolution. Number of sectors is NOT fixed. One problem is that many of the MFM controllers were into interchangeable. For example a 5mb St506 formatted with my Teltek S100 controller is NOT readable by any WD based controller or for that fact even with a Compupro S100 st506 controller!!! Seems the underlying format (ID, gaps, Sync...) is not standardized at all. Further In the DEC world there were RQDX1/2/3 controllers, the RQDX1/2 were compatable and used the same format as they were the same board (ignoring firmware upgrades and some logic fixes). The RQDX3 however was a differnt animal and required a reformat of the drive (or a specificly RQDX3 formatted replacemen) to use it. In the PC world the WD1003 was a common standard for MFM and the 1005 was a RLL so you alreay had the same drive and two possible formats. Same was true for other systems I'm sure. >Even if that is the case, I wouldn't have thought it makes much difference - >it just means that buffer memory and permanent storage is organised a little >differently. The device is still like a big floppy, just with more heads and >the need to record faster timings between bit transitions: the principle's the >same, it just needs someone with experience of working with fast logic to >design the board layout and code for whatever CPU / DSP is used. There is a notable differnce from say a hard sectord NS* floppy to a 1771 soft sectored TRSdos floppy from a floppy from a system using a 1791. Thats a lot of distance to cover. Sure you can store it as a pattern of bits and it's only possible as ram or some non-moving storage is now cheap. Of course the problem of storage viability over time (longevity of media) is still and issue. Allison

17 years, 9 months

TU56 and TC11 racked

by wacarder＠earthlink.net

Here are some pics of the TU56 and TC11 racked. http://www.woffordwitch.com/TU56projectNum2.asp I would like to hear from anybody who has ever used Dectapes on a PDP-11. This is new territory for me. Ashley

17 years, 9 months

MFMulation? (Solid-state replacements for MFM drives)

by ajp166＠bellatlantic.net

> >Subject: MFMulation? (Solid-state replacements for MFM drives) > From: M H Stein <dm561 at torfree.net> > Date: Mon, 16 Apr 2007 03:23:54 -0300 > To: "'cctalk at classiccmp.org'" <cctalk at classiccmp.org> > >Date: Sun, 15 Apr 2007 23:05:49 +0100 (BST) >From: Entity <entity at nenevr.demon.co.uk> >Subject: MFMulation? (Solid-state replacements for MFM drives) > ><snip> >>I've got a Northstar Horizon that I mentioned on here many, many years >>ago and I've just started looking at it again; once I've got it up and >>running it'd be nice to add some sort of permanent storage, but without >>jettisoning one of the floppy drives. The SuperIO board is one option, >>but I'd like to keep it as stock-Northstar as I can. ><snip> >------------- >If you mean Howard Harte's SuperIO board, apparently he's no longer >making or supporting it; too bad. > >mike Thats also a factor. One I'd point out is the only reason for stock NS* Horizon is NSDos (and related NS* software) as the dos is locked to the disk controller hardware. Once you use another disk interface (ANY) NSDos is a non player and CP/M or one of the similar OSs becomes the choice as you can create your own BIOS to match whatever IO hardware you have. An NS* horizon as a S100 crate is a good system and with a higher density FDC or HDC added and CP/M it has a place as a retro system or as an example of hobbiest systems of the time. It was not uncommon to upgrade a NS* with denser disks or even add a hard disk of some form. For the extreme user, since NSDos is on the net in assembly form it's possible to rewrite it to use a differnt disk or disk equivilent. I've played with that so it can be done. Allison

17 years, 9 months

Fortune 32:16

by jam＠magic.com

> Do you recall anything about how they coded the machine ID to the > software disks. I believe I have some add on programs that have not > been installed. Most though have machine ID numbers written on the > floppy disks. > I have a couple of these machines here one has an bad Motherboard. The copy protection was quite involved. If I recall, all or portions of the software were encrypted using DES, even when it was stored on the hard drive. Each system had a unique PAL device that was used as part of the decryption process so no two systems could share the same encrypted copy of the software. James Markevitch

17 years, 9 months

ST506 WTB:Micropolis 1325

by ajp166＠bellatlantic.net

> >Subject: Re: ST506 WTB:Micropolis 1325 > From: "Andy Piercy" <andy.piercy at gmail.com> > Date: Tue, 10 Apr 2007 00:15:50 +0100 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Alison, thanks for the info, I'll have a go at opening one of the driver, as >currently they are only as much use as a large paper weight! The basic problem is the head arm is stuck to the head park bumper. One temporary fix reported was to freeze the drive rendering the bumper unsticky. Things to know: Never move the heads on the platters if they are not rotating at speed. Never touch platters. Never use magnetic tools near platters (closer than 1"), that means tools that may have remnant magnetism as well. demag them first! You can spin the disk up (just apply power) with the cover off and watch the head load action after bumper fix. Once operational, the first thing I do with the drive is cover it up and put it in a system where I back it up FIRST to another known good drive. Just in case!!! The reason is to a know good drive is faster the copy the less time the drive has if it's going to fail. I had one that failed not for HDA reasons but once the HDA was working I found it would heat up and quit (bad logic board). One last item The RD53 and RD54 drives run hot (around 35W) and lots of cooling was one way to insure they lasted longer. Heat is the enemy of those older drives and it is not unusual to find a system there the fans were dead or clogged and the drives failed.. Allison > >Sridhar, > >A clean box sounda a good idea, could you provide some detaile please? > >Thanks, > >Andy. > > > > >On 09/04/07, Sridhar Ayengar <ploopster at gmail.com> wrote: >> >> Andy Piercy wrote: >> > So anyway sorry to ramble, After you opened the drive, did you have any >> > problems with dust and head crashes? Do you think that it would be >> possible >> > to fabricate one of these bumpers? Do you have any pictures of this >> bumper >> > within the drive? >> >> You could always make a cleanbox to do the work in. It isn't difficult. >> There are plans available online, but if you have trouble finding >> them, I'd be willing to describe how I did it. >> >> Peace... Sridhar >>

17 years, 9 months

MFMulation? (Solid-state replacements for MFM drives)

by ajp166＠bellatlantic.net

> >Subject: MFMulation? (Solid-state replacements for MFM drives) > From: Entity <entity at nenevr.demon.co.uk> > Date: Sun, 15 Apr 2007 23:05:49 +0100 (BST) > To: cctalk at classiccmp.org > > >Hello, all. > >Does anyone on the list know if anyone in our extended community has ever >come up with some sort of plug-compatible flash memory replacement for MFM >drives? No. Flash has a write limit before failure. that makes it useless for swap/page space. Also the number of CHS combinations of old disks were numerous. >I've a vague idea that I've seen a commercial offering at some point in >the past, but obviously that'd be a fairly expensive move to make. >(Fairly? Oh, OK. Very.) > >I've got a Northstar Horizon that I mentioned on here many, many years >ago and I've just started looking at it again; once I've got it up and >running it'd be nice to add some sort of permanent storage, but without >jettisoning one of the floppy drives. The SuperIO board is one option, >but I'd like to keep it as stock-Northstar as I can. CF to s100 takes maybe 10 peices of generic ttl, It would require a new (or argumented) bios for CP/M and NSdos never supported a hard disk (or similar) without a rewrite (except on the Advantage). I've done both IDE and CF for 8085 and z80 systems as a way to get bulk storage for them. It's easy to do in hardware and a software project as there is no direct support off the shelf (one of hardware). Allison

17 years, 9 months

Atari ST/STacy was Re: MCM66128L20

by jvdg＠sparcpark.net

Ensor wrote: > > 1040ST lacked a floppy drive. 520STF and 1040STF had floppy drives > >(hence the 'F'). > > Here in the UK we got the "520STM" (no floppy, internal RF modulator) and > "1040STF" initially, and later the "520STFM"; I don't recall if there was a > "1040STFM". There was. I have one. You are right, as the 'F' indicates the internal floppy drive, the 'M' indicates the modulator. I was wrong, earlier, though; there was no floppy-less 1040ST. The 1M ST was called the 520ST+. This was probably done to make things interesting. ,xtG tsooJ

17 years, 9 months

MFMulation? (Solid-state replacements for MFM drives)

by dm561＠torfree.net

Date: Sun, 15 Apr 2007 23:05:49 +0100 (BST) From: Entity <entity at nenevr.demon.co.uk> Subject: MFMulation? (Solid-state replacements for MFM drives) <snip> >I've got a Northstar Horizon that I mentioned on here many, many years >ago and I've just started looking at it again; once I've got it up and >running it'd be nice to add some sort of permanent storage, but without >jettisoning one of the floppy drives. The SuperIO board is one option, >but I'd like to keep it as stock-Northstar as I can. <snip> ------------- If you mean Howard Harte's SuperIO board, apparently he's no longer making or supporting it; too bad. mike

17 years, 9 months

Epson PC286UX

by brettdurham＠mybluelight.com

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17 years, 9 months

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test-drb April 2007