Re: An historical nit about FDDs
On 07/14/2018 07:57 AM, Noel Chiappa via cctalk wrote: > From: Jon Elson > I THINK the 370/145 used the same drive. The "IBM's 360 and Early 370 Systems" book doesn't say so explicitly (it just says Minnow - the one with the solenoids - was a"incorporated in .. the System/370 processors", pg. 517), but given that the follow-on drive (Figaro/Igar) didn't start shipping until 1973 (pg. 519), and the /145 started shipping in 1971, it pretty much had to have had a Minnow. Well, there were two major variants of the 370/145, that had major changes at least to the power system. The first version had many small power regulator modules, the later had two HUGE regulators (390 A each, at +1.25 V and -3 V). So, they could have updated a bunch of other features at the time of that change. Jon
Re: An historical nit about FDDs
> From: Jon Elson > I THINK the 370/145 used the same drive. The "IBM's 360 and Early 370 Systems" book doesn't say so explicitly (it just says Minnow - the one with the solenoids - was a"incorporated in .. the System/370 processors", pg. 517), but given that the follow-on drive (Figaro/Igar) didn't start shipping until 1973 (pg. 519), and the /145 started shipping in 1971, it pretty much had to have had a Minnow. Noel
Re: An historical nit about FDDs
On 07/13/2018 01:04 PM, Tom Gardner via cctalk wrote: Jon: The 23FD used on most S/370 mainframes had a two solenoid and swash plate actuator, pulse the in solenoid to go in and the out solenoid to go out. IBM SJ in those days was very cost conscious and preferred mechanical parts over electronic, hence this mechanism instead of the stepper motor implement by most (all?) other FDD manufacturers. Right, this is what I heard and saw on a 370/168. I THINK the 370/145 used the same drive. Jon
RE: An historical nit about FDDs
Jon: The 23FD used on most S/370 mainframes had a two solenoid and swash plate actuator, pulse the in solenoid to go in and the out solenoid to go out. IBM SJ in those days was very cost conscious and preferred mechanical parts over electronic, hence this mechanism instead of the stepper motor implement by most (all?) other FDD manufacturers. Chuck and Paul: It's all relative - key to disk systems were taking off and the IBM 3470 blessed the market. The 1973 Shugart Associates business plan acknowledged Memorex as the then market leader in FDDs - MRX had Mohawk Data Systems and had shipped product to 45 potential customers. SA estimated the market to be 327k units in 1973 growing to 633k by 1977, a big number in the 1970s and big enough to attract venture capital. The big customer turned out to be Wang which SA won. The FDD and FD were invented by a number of folks at IBM most of whom did join Al at Memorex see: https://en.wikipedia.org/wiki/History_of_the_floppy_disk#/media/File:FDD_patents_collage.png All: The first product was the SA900 not the SA800; it had a step/direction interface, and my guess now it was to save an IC or two in the circuits to drive the stepper motor. Tom -Original Message- From: Jon Elson [mailto:el...@pico-systems.com] Sent: Thursday, July 12, 2018 6:41 PM To: Paul Berger; gene...@ezwind.net; discuss...@ezwind.net:On-Topic and Off-Topic Posts Subject: Re: An historical nit about FDDs On 07/12/2018 01:40 PM, Paul Berger via cctalk wrote: > IBM created the 8" diskette as an inexpensive and reliable means of > loading microcode and shipped the first read only drives in 1971. I am quite certain the original FDD on the 370/168 used a pair of solenoid coils to ratchet the head in and out. I think the mechanism was a leadscrew and toothed wheel. I heard a 370/168 loading a microcode overlay and it sounded like a machine gun, even in a pretty loud machine room. I think the same scheme was used in the 370/145. Jon -Original Message- From: Chuck Guzis [mailto:ccl...@sydex.com] Sent: Thursday, July 12, 2018 12:05 PM To: Paul Berger via cctalk Subject: Re: An historical nit about FDDs On 07/12/2018 11:40 AM, Paul Berger via cctalk wrote: > Because IBM never sold the drives themselves and the market impact of > the first Memorex drive may not have been really big, there was no > real standard so when Shugart Associates released the SA800 its proved > to be very popular and its interface became the defacto standard. One thing that escapes modern sensibilities is how expensive the first floppy disk systems were. If you purchased one of the early microcomputers (IMSAI, Altair), a single-drive floppy disk system would run more than the CPU unit. Remember, there were initially no LSI floppy controllers--on the MDS, Intel rolled their own as a 2-board Multibus set. Some early systems used USART chips. IMSAI used another 8080 MPU for their controller. Data separation was a fairly new problem too, as floppy ISV and general signal stability was not as good as most hard drives. You're essentially using flexible, disposable media. So initially, the market was not terribly large. --Chuck
Re: An historical nit about FDDs
On Wed, Jul 11, 2018 at 11:12:59AM -0700, Tom Gardner via cctalk wrote: > Anyone know where the Step/Direction version of the FDD interface > originated. > > So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex > 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the > motor. Having step-in and step-out gives the opportunity to do both at the same time, which is unlikely to go well. Step and direction just seems neater to me because it's essentially equivalent to clock/strobe and data, but perhaps that's just my modern prejudices. The choice of which scheme probably boils down to which was the idiomatic way to do sequential logic when the respective devices were designed. I wonder how one might design a floppy interface today. I suspect that it'd end up as a pair of TMDS links with some complex high-level multiplexing scheme.
Re: An historical nit about FDDs
On 07/12/2018 01:40 PM, Paul Berger via cctalk wrote: IBM created the 8" diskette as an inexpensive and reliable means of loading microcode and shipped the first read only drives in 1971. I am quite certain the original FDD on the 370/168 used a pair of solenoid coils to ratchet the head in and out. I think the mechanism was a leadscrew and toothed wheel. I heard a 370/168 loading a microcode overlay and it sounded like a machine gun, even in a pretty loud machine room. I think the same scheme was used in the 370/145. Jon
Re: An historical nit about FDDs
On 07/12/2018 11:40 AM, Paul Berger via cctalk wrote: > Because IBM never sold the drives themselves and the market impact of > the first Memorex drive may not have been really big, there was no real > standard so when Shugart Associates released the SA800 its proved to be > very popular and its interface became the defacto standard. One thing that escapes modern sensibilities is how expensive the first floppy disk systems were. If you purchased one of the early microcomputers (IMSAI, Altair), a single-drive floppy disk system would run more than the CPU unit. Remember, there were initially no LSI floppy controllers--on the MDS, Intel rolled their own as a 2-board Multibus set. Some early systems used USART chips. IMSAI used another 8080 MPU for their controller. Data separation was a fairly new problem too, as floppy ISV and general signal stability was not as good as most hard drives. You're essentially using flexible, disposable media. So initially, the market was not terribly large. --Chuck
Re: An historical nit about FDDs
IBM created the 8" diskette as an inexpensive and reliable means of loading microcode and shipped the first read only drives in 1971. Memorex did ship a hard sectored R/W drive some time in 1972 likely because Alan Shugart had jumped ship from IBM to Memorex. Some sources credit Shugart with inventing the diskette drive but that is not true he had given the job to others on his team. The Memorex 650 seems to have an interface very similar to the IBM drives oddly enough, using step in and step out signals. The next year IBM shipped its first R/W drive the single sided 33FD "Igar" a single sided soft sectored drive and larger capacity. It was first used in the 3741/42 key to diskette machines but was used in a wide variety of IBM machines, as far as I know IBM never sold the bare drives. Because IBM never sold the drives themselves and the market impact of the first Memorex drive may not have been really big, there was no real standard so when Shugart Associates released the SA800 its proved to be very popular and its interface became the defacto standard. Paul. On 2018-07-12 3:02 PM, Tom Gardner via cctalk wrote: Hi Chuck I agree it is easy to convert but I am surprised that a start-up would have the guts to change the "standard," whether it was Memorex, Potter or Century. I think before the 33FD Memorex was the market leader but I could be wrong. I've asked some SA founders the question. Does anyone know any Potter or Century FDD people from the early 70s? The early HDD interfaces I am aware of used a control cable with an 8-bit bus and a set of tag lines to define the bus - much more expensive to implement than the Step In/Step Out. Regards, Tom -Original Message- From: Chuck Guzis [mailto:ccl...@sydex.com] Sent: Wednesday, July 11, 2018 11:38 AM To: Tom Gardner via cctalk Subject: Re: An historical nit about FDDs On 07/11/2018 11:12 AM, Tom Gardner via cctalk wrote: Anyone know where the Step/Direction version of the FDD interface originated. So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the motor. The earliest Step/Direction FDD I can find is the Shugart 800 which first shipped in September 1973. Shugart is probably it, unless there's a hard drive interface that precedes it. Mostly a minimal bit of logical difference between the Step in/Step out and Step/Direction. One can be converted to the other rather easily. --Chuck
RE: An historical nit about FDDs
Hi Chuck I agree it is easy to convert but I am surprised that a start-up would have the guts to change the "standard," whether it was Memorex, Potter or Century. I think before the 33FD Memorex was the market leader but I could be wrong. I've asked some SA founders the question. Does anyone know any Potter or Century FDD people from the early 70s? The early HDD interfaces I am aware of used a control cable with an 8-bit bus and a set of tag lines to define the bus - much more expensive to implement than the Step In/Step Out. Regards, Tom -Original Message- From: Chuck Guzis [mailto:ccl...@sydex.com] Sent: Wednesday, July 11, 2018 11:38 AM To: Tom Gardner via cctalk Subject: Re: An historical nit about FDDs On 07/11/2018 11:12 AM, Tom Gardner via cctalk wrote: > Anyone know where the Step/Direction version of the FDD interface > originated. > > So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and > Memorex > 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control > of the motor. > > The earliest Step/Direction FDD I can find is the Shugart 800 which > first shipped in September 1973. Shugart is probably it, unless there's a hard drive interface that precedes it. Mostly a minimal bit of logical difference between the Step in/Step out and Step/Direction. One can be converted to the other rather easily. --Chuck
Re: An historical nit about FDDs
> So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex > 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the > motor. Someone asked (you?) on one of my Youtube videos for more detail about the 23FD's stepping method, so I made a video covering the finer details. https://youtu.be/AMPlJ7JayB4 -- Will
Re: An historical nit about FDDs
On 07/11/2018 11:12 AM, Tom Gardner via cctalk wrote: > Anyone know where the Step/Direction version of the FDD interface > originated. > > So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex > 650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the > motor. > > The earliest Step/Direction FDD I can find is the Shugart 800 which first > shipped in September 1973. Shugart is probably it, unless there's a hard drive interface that precedes it. Mostly a minimal bit of logical difference between the Step in/Step out and Step/Direction. One can be converted to the other rather easily. --Chuck
