Well, as long as you think along a 'real' drum with flying heads etc. you're right, but there is a simple solution - take a card board tube and warp regular cassete tape around, and let a head read/write this tape ... if you take an old style washing powder drum (ca. 30 cm diameter / 1 ft) you get a lenght of about 1m (3 ft 4") - what was the usual speed of cassetes ? 4 cm/s ? I'm not shure (Tony ?), as a rough estimation you get a track size of some 3 kByte and an average access time of 12s not to bad ... almost like a floppy (well, except the access time) and of course we can add more tracks ... and with seperate heads for each track the over all performance would be comperable to early floppy drives. The only real problem might be the head(s) - or better the acuracy of the tape, since the head is fixed. You may need a real good way to adjust the tape. Otherwise you need some head mechanics so the head may follow your tape ... Now if you invest this much effort, you may also glue the tape in a spiral along the drum - like a good old vinyl disk (you know, the courious black stuff they had before CDs) or well, on a CD. All you need is to add a mechanic to lift the head, and you get one big tape with direct access and fast loading, since you don't need to switch tracks within a read operation. For the head movement a simple thread rod and a stepping motor could work fine. With our washing powder drum we could get around the same storage than on a 8" disk (~500K) with still acceptable access time (no idea hof fast the head positioning will be, but at least it must be able to move the head within one rotation as fas as the tape is wide (plus a bit for the 'track gap') - I just assume it would be possible to move the head 10 times faster when lifted. putting this together (140 Rounds, 25s per round, 2,5s per track lifted movement) we get a maximum, seek time of <400s, and an average seek of <200s or 3 minutes ... not so bad for a old card board drum :)) A real killer would be a TOC at the start of your drum. But with a little inteligent programming the average timing may be quite good (for example do seek operations already when you are still computing the last data chunk, etc.) Also you may turn the head at the end ... like car cassete systems, and have a second 'side' backwards - now we have a whooping Megabyte. And we need a programm controled direction change for the drum (plus brake and spin up wait). Maybe place it in the middle - or just forget about it at all. Oh ja, for your tape thing - putting a directory at the begining of the tape is quite a pain - maybe you should take a look at old IBM manuals for tapes. They had fast tapes, with automatic loading, and _realy_ fast for/backwinding, Reading in both directions, etc. pp. but still their tape data structure (VOL1/2/3, HDR1/2/3, etc.) didn't include any central directory structures. Last but not least, there is still the endless tape! This device is way more like what you think about ... 5 min endless cassettes should be still available for some answering machines - you get a storage of some 35 kByte which should be fair enough. Gruss H. -- VCF Europa 3.0 am 27./28. April 2002 in Muenchen http://www.vcfe.org/

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Well, there are special cassetes available for answering machines and/or voice services. During the last years most of said apps have been replaced by digital recording, but replacement tapes are still available... usualy they have only a very short length. the maximum I know is good for 5 minutes - most are only good for 30 seconds. Gruss H. -- VCF Europa 3.0 am 27./28. April 2002 in Muenchen http://www.vcfe.org/

On Wed, 16 May 2001, Tony Duell wrote: You're assuming he won't do something clever such as add an electronic counter so he can fast forward to just before the desired block? As I suggested, he can use the magnetic tape to wrap around some drum to create a cool drum memory device :) There can even be multiple tracks, with either one moveable head or multiple heads for faster access. I think the intent here is to create a more classic-type design rather than a modernish design. Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org

On Wednesday 16 May 2001 14:05, Sellam Ismail hit his keyboard with a hammer and this was the result: I was planing on this. I will have a block of sound at the start of the tape, that will indicate what is 1 second for this recorder. This will calibrate it to be able to seek the second of the tape it wants. It will then read in the FAT and seek the file directly. I was thinking of reading/writing the tape's both tracks at once. I think I would probably run it more as a showpiece than a functional device and still have a floppy drive for other stuff. David -- David Findlay ---------- Email: david_j_findlay(a)yahoo.com.au Homepage: http://users.bigpond.com/nedz/ Segmentation Fault. (Core dumped)

Also this would almost need a seperate CPU for tape control. Otherwise the Computer would be more like a ZX81 - with all the fine tuning needed for timing your programm code with the tape hardware. Although it sounds like a fun project, I would skip this and go for a simple solution. Gruss H. -- VCF Europa 3.0 am 27./28. April 2002 in Muenchen http://www.vcfe.org/

Tony you hit on the one and only practical application of Calculus I've had since leaving College 20 years ago, and an amateur application at that. Of course I still respect Calc immensely, in SW it just isn't used. (HW I imagine is a different story). John A.

On Wednesday 16 May 2001 11:10, Tony Duell hit his keyboard with a hammer and this was the result: Well, the reason I wasn't going to use a floppy drive was the fact that I would have to build an IDE controller. How hard are they to build? David -- David Findlay ---------- Email: david_j_findlay(a)yahoo.com.au Homepage: http://users.bigpond.com/nedz/ Segmentation Fault. (Core dumped)

Well, if we are talking about modern day I/O interface for a home brew system, I'd strongly recomend USB. Single chip USB controlers offer a great deal of flexibility with a simple interface, ready for 8 or 16 bit systems. And you may get almost any peripherals for USB, including _any_ kind of mass storage. Gruss H. P.S.: some years ago I would have used SCSI -- VCF Europa 3.0 am 27./28. April 2002 in Muenchen http://www.vcfe.org/

Well, high sophisticated stuff like an Atmel 43USB320 will work fine as host controllers ... and you even can put 'dynamic' hardware in your design (as little programms for the integrated 8 Bit CPU. Or take the Infineon SAB C161U, a nice 16 Bit CPU (or SAB-C541U if you prefer 8051 CPU style - there are similar x51 CPUs from Texas and Intel of course). For all of these some serious twiddeling is required of course. Then there is at least one PowerPC Chip capable of USB Host functions from Motorola: MPC 850 Anf if I remember correctly Cypress offers also a nice uP with USB on board, capable of acting as host ... at least I remember some application note. Of course, there ae simple USB host controllers without a (visible) CPU, like one from Scanlogic with several version, capable to act as root hub or controller and a very fine and universal 8 or 16 Bit interface - my personal favorite - and there is the Transdimension UHC124 - very similar, but additional features. Next there are FPGAs (like the Kawasaki USBx, with or without on chip uP) And last but not least, some companies offer USB Controllers as IP for standard FPGAs (LSI Lucent or Sand) Or, after all take just a serial interface and a USB Transciever :) Gruss H. -- VCF Europa 3.0 am 27./28. April 2002 in Muenchen http://www.vcfe.org/