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Forum Index : Microcontroller and PC projects : CMM2 Floppy Drive, Is it possible?
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RetroJoe Senior Member  Joined: 06/08/2020 Location: CanadaPosts: 290 |
Indeed - spreadsheets have been *the* killer app in the 8-bit (VisiCalc), 16-bit (Lotus 1-2-3) and 32-bit (Excel) eras. Sometimes they can turn around and kill your business, though - I call it “The Enron Effect”. Edited 2020-12-30 14:57 by RetroJoe Enjoy Every Sandwich / Joe P. |
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| Volhout Guru  Joined: 05/03/2018 Location: NetherlandsPosts: 3557 |
https://en.m.wikipedia.org/wiki/Western_Digital_FD1771 Practically all floppy drive interfaces for all 8 bit computers where using these chips.. except commodore and apple. They had propriatary solutios. The Apple solution was software for a large part, cpu clock timed. You will not get that to work on the cmm2. Your best way to success is reverse engineer what the others did. You pick an 8 bit computer that you have a dissasembled DOS from, find the schematcs, see what circuit they used, and copy it. Connect that circuit to the 40pin connector. In Uk I would look at the acorn ATOM . In their archives they have the DOS rom, it was a separate ROM. There are schematics of the disk interface. If you contact them on the stardot forum, they will help you getting a disassembly of the ROM, and may even have a commented disassembly. Oh yeah...do you remember that all floppy formats where propriatary? And not interchangeable. Whatever you do, you will not be able to exchange floppies with other systems... Edited 2020-12-30 19:57 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3557 |
If you need a storage solution that looks and sounds like a floppy, just for nostalgic reasons, a simpler solution can be found in a mockup. Running a floppy drive motor, and making some random head stepping is only few lines of code. Then you glue the circuit board of a usb stick in a cutout of a floppy disk, and glue a usb A connector on the head of a diskdrive, or at some other fixed position in the mechanics. Storage ensured, sound and appearance correct. And minimal work. Even the drive led can be turned on and off woth the drve select line. PicomiteVGA PETSCII ROBOTS |
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romba6 Newbie  Joined: 04/07/2020 Location: United KingdomPosts: 37 |
I've built and used the WD37C65C with a 3.5" floppy on my RC2014 and SC126 running CP/M etc., example circuit below. You can buy these ICs on Ebay - with care!!! http://www.smbaker.com/wordpress/wp-content/uploads/2016/12/rc2014-floppy-wd-sch.png Hooking one onto the CMM2 certainly doable BUT a bit of work involved - but fun!!!, you wouldn't of course need all the peripheral components. |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
There is always some nut-case with too much time on his hands  Floppy SD card for the retro look |
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| William Leue Guru Joined: 03/07/2020 Location: United StatesPosts: 383 |
This is kind of the opposite of the general trend in retro-computing. Many people are selling or working on floppy disk emulators that actually use an SD card or some other flash-based memory such as a thumb drive for the actual storage, and then a few FPGA chips that emulate the floppy drive interface. -Bill |
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| Kingeorg Newbie Joined: 28/12/2020 Location: United StatesPosts: 11 |
Mad, but PRETTY COOL! |
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| Kingeorg Newbie Joined: 28/12/2020 Location: United StatesPosts: 11 |
Yes, I have always preferred to row against the (Main)stream...  |
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| RetroJoe Senior Member Joined: 06/08/2020 Location: CanadaPosts: 290 |
That SD card in a 3.5 floppy shell is brilliant - you can’t hear it in the video, but I wonder if he managed to get the drive motors to activate when the PC is accessing the SD card? Another cool idea that would work brilliantly with the CMM2 would be an SD card emulator that you can modify via USB. It would look like a normal USB flash drive (or drives - ideally it would support multiple partitions) to a Windows PC, but the SD card reading device (e.g. the CMM2) would think it’s reading a physical SD card. I’ve seen a few attempts at such a device, but AFAIK nobody has a completed project. Edited 2020-12-31 03:36 by RetroJoe Enjoy Every Sandwich / Joe P. |
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| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 387 |
ATA CD player on arduino...maybe good for soundtracks etc ? |
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| mkopack73 Senior Member Joined: 03/07/2020 Location: United StatesPosts: 261 |
the old Tandy Radio Shack Model 100 (102) portables used an RS-232 serial interface to control their floppy drives. I cobbled something together using a serial TTL convertor, talking to a Teensy Microcontroller running a little program that uses it's microSD card as the floppy drive. Was an cheap and easy way to get storage onto my Model 100. But like others have said, it all depends on the floppy drive in question. The smarter drives (like the commodore) ones might be easier since they handle a lot of the low-level stuff for you and you're simply requesting it to send or receive data over serial... |
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| frnno967 Senior Member Joined: 02/10/2020 Location: United StatesPosts: 104 |
I found this video from an article on Hackaday. Reminded me of this thread. Maybe his design could be adapted for the CMM2? Link to the video Hackaday article Jay Crutti: Ham Radio Operator, K5JCJ. Computer Enthusiast. Musician. Engineer. |
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| Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 814 |
Hi, here is a floppy drive on a Raspberry Pi . :)Frank |
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| Kingeorg Newbie Joined: 28/12/2020 Location: United StatesPosts: 11 |
That is wonderful! See I'm not the only one looking for that "retro factor"... I'll try to get a hold of Mr. baker to see if he can guide me in the right direction about implementing it for the CMM 2. Thanks |
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Plasmamac Guru Joined: 31/01/2019 Location: GermanyPosts: 501 |
Arduino floppy Plasma |
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| Kingeorg Newbie Joined: 28/12/2020 Location: United StatesPosts: 11 |
Interesting, but I'm not sure as to how implement it to work with the MM2. Thanks nevertheless. |
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| Vampire05 Regular Member  Joined: 06/12/2020 Location: GermanyPosts: 88 |
Hi Guys, yesterday i have tried the arduino floppy (ArduinoFDC) with ArduDOS, it works great. Here the ArduDOS Commands:  The both XMODEM commands "send filename" and "receive filename" sounds interesting for data exchange between floppy and CMM2. I have two questions: 1) Is it possible to use the XMODEM command on the CMM2 to send and receive ANY filetype over COM1? (Not only .BAS files) 2) Is there an easy way to store some MMBASIC Functions in the flash memory of CMM2? My Idea is, save the floppy driver in the flash and not on the SD Card. Best regards Edited 2021-07-26 18:43 by Vampire05 |
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| Kingeorg Newbie Joined: 28/12/2020 Location: United StatesPosts: 11 |
Getting closer... But no CMM2 yet.  |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5735 |
AFAIK you can send any sort of file using XMODEM, but I don't think the CMM2 makes any sense of file extensions and will treat them all as ASCII. I might be wrong. There's no user access to the flash on the CMM2 where MMBasic is stored. There is a 4k area of battery-backed RAM used by VAR which might be of some use, otherwise all storage is on the SD card. The main RAM is overwritten by the editor when there is no program running. When a program is run it is first copied into main RAM, overwriting the editor, then run. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5913 |
XMODEM will send/receive any file type. Just be aware that the file will get padded with chr$(27) or chr$(0) to bring the file up to a multiple of 128 bytes. Which padding gets used depends on the particular implementation and you have to handle either. This is not usually a problem for programs and images but can cause grief with files that get appended to such as log files. You will have to code around it. Jim VK7JH MMedit  MMBasic Help |
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