aim-65 floppy disk control

[ptorric]

orac wrote:

Wikipedia of course!

after looking a lot around i find this http://www.s100-manuals.com/download/FD235HF-A429.pdf that i think can be useful.

btw: 6502 projects for using a normal pc floppy disk? (that can be considered as larger as an harddisk if compared with normal ram for a 6502 pcb project )

[fachat]

ptorric wrote:

orac wrote:

Wikipedia of course!

after looking a lot around i find this http://www.s100-manuals.com/download/FD235HF-A429.pdf that i think can be useful.

btw: 6502 projects for using a normal pc floppy disk? (that can be considered as larger as an harddisk if compared with normal ram for a 6502 pcb project :) )

http://www.6502.org/users/andre/csa/drvio/index.html
has a WD177x-based floppy-drive interface, compatible with the Commodore VC1581

In http://www.6502.org/users/andre/csa/shug/index.html
you don't need the CIA 8520/6526.

The WD177x, however, are hard to come by these days. It's probably better looking into SD-Card interfaces today, or USB-drives.
I'm working on that as well, but it'll take a while...

André

[ptorric]

fachat wrote:

The WD177x, however, are hard to come by these days. It's probably better looking into SD-Card interfaces today, or USB-drives.
I'm working on that as well, but it'll take a while...

André

Really thank André.
I dont know wd1722, it seems a buffer/driver.
In your opinion, is it possible to directly drive (but a power driver) the floppy via a 6522?
I think the main problem is timing...

[fachat]

ptorric wrote:

I dont know wd1722, it seems a buffer/driver.
In your opinion, is it possible to directly drive (but a power driver) the floppy via a 6522?
I think the main problem is timing...

The WD1770/1772/177x are in fact disk drive controllers, with some (small) intelligence inside. You store a command into the command register and can then read the results in another register, or write data to another register that is written to disk.

You could probably replace the WD177x by discrete logic ICs (74LS*), similar to the first Commodore disk drives that used discrete logic (see for example the schematics for the (early) VC1541 drives http://www.zimmers.net/anonftp/pub/cbm/ ... index.html
(note that later drives combined a lot of logic into a custom IC. With the "long board" schematics with the discrete logic you can actually see how the GCR encoding in CBM floppy drives work)
Or you can look at the even older IEEE488 dual drives like the 2040 http://www.zimmers.net/anonftp/pub/cbm/ ... index.html that use discrete logic as well (but with a different data <-> GCR en-/decoding, using a ROM chip).

The WD177x, however, use MFM as encoding, not the Commodore GCR encoding, so you would have to do the schematics yourself (or maybe find an ancient discrete logic MFM controller schematics). From a timing point of view it is only feasible by using some kind of shift registers, so that the 6502 only needs to handle data bytes, not bits. OTOH, that holds true for 1 or 2MHz 6502, maybe a 16MHz 65816 could even do the bits.

André

[orgwood]

orgwood wrote:

Hi guys, I just found my ah5050 board and schematic that interfaced to the AIM65 and used the 1541 disk drive ...any interest in communicating?

DaveC

I have been developing a new 6522 board using the code and hardware from this vintage board that is now working for the AIM-65 to interface to the C1541. You pull the application 6522(hopefully you aren't using the I/O ports that this needs) and plug in my VEB Vertical Expansion Board. You can find it on ebay under my store Rootskiceller. I am working on getting it to work with an SD card emulator. The image shows my prototype but my production boards are much cleaner and not nearly so tall.
My email has also changed to orgwood65@gmail.com

[dwight]

It was mentioned in an earlier post that a HD was out of the question. This is not true if the HD is a ATA IDE interface. The disk reads/writes a sector and puts it in a buffer for one to read/write at any rate one wants.
I like the idea of using an SD card though. If done right, data can be transferred to and from a machine on the net. One doesn't have to use a regular fat. You can use that on the alternate machine side but simply have fixed size files the your 6502 system could treat as individual disk. This makes access from the 6502 side simpler since it doesn't need as much knowledge of the fat system used, only the offset to the particular file.
Dwight

[orgwood]

dwight wrote:

It was mentioned in an earlier post that a HD was out of the question. This is not true if the HD is a ATA IDE interface. The disk reads/writes a sector and puts it in a buffer for one to read/write at any rate one wants.
I like the idea of using an SD card though. If done right, data can be transferred to and from a machine on the net. One doesn't have to use a regular fat. You can use that on the alternate machine side but simply have fixed size files the your 6502 system could treat as individual disk. This makes access from the 6502 side simpler since it doesn't need as much knowledge of the fat system used, only the offset to the particular file.
Dwight

The AIM-65 C1541 interface uses the user 6522 with 5-6 I/O lines and I've tested it with the tfw8b Classic C-1541 SD emulator. I tried formatting a 1GB SD card first but ran out of room for 6502 files so I upgraded to a 2GB card so now I have plenty of room to work with. I plan on trying a 4GB card soon as I have a few of these micro cards that I can fit into the SD adapters. The 2GB card was read by my older XP laptop that has a built in Large SD reader/writer that won't go above that capacity so it was my default choice. The 4GB cards and up with go into a USB reader for testing. I formatted several 4GB cards recently and tried to read them on the AIM-65 for blocks available. There is a substantial increase I think because the 2GB cards normally have around 600 blocks while the 4GB cards show over 6000 blocks free.

My AIM-65 interface is now available on eBay under my store name Rootskicellar. I would make a special price offer to those here on the group if it would get some of these into the hands of some users. Any interest? I'm thinking the software on a 2532 for the AIM, card with cable to the C-1541, a 6522 mounted and tested and manual on CD would run about $100. I could lower the price by $25 if I provide both the software and manual on CD. This software would have to be disassembled by someone much more knowledgeable than me and reassembled for your particular machine since it was developed for the D000H socket on the AIM and uses the I/O devices in the monitor program. This program was provided by ABC Inc Alex Blanco and sold by Dynatem after they purchased the rights to the AIM-65 AIM-65/40 and RM65 line in the early 1980s. I was a distributor for both Rockwell and Dynatem under my company EXCERT Inc. Educational Computer Division. I would like to see if it is adaptable to daisy chaining so both the C-1541 and the SD emulator can be present and usable at the same time. I am not certain that the software currently supports that.

I am really needing some suggestions on how to daisy chain the C1541 Floppy Drive to the C1541 SD emulator so I can transfer files directly between them. I found some more files on old disks that a customer said she found in the documents that will allow an interface to BASIC and FORTH. There are also some demo files, etc that could prove quite valuable to today's USERS.

[tgmaxx]

RichCini wrote:

Mike Naberezny wrote:

Using the Commodore drive is a good solution for many homebuilt projects as it already has some intelligence built-in. Richard Cini and I have been working on this for some time and he has successfully extracted the serial communications routines from the VIC-20 KERNAL, cleaned them up, and successfully reimplemented them on Daryl Rictor's SBC-2 board.

This is very true. I wanted to use this setup for a data logging application, and printers and drives are cheap.

I'd like to add that not only are the raw routines implemented, but they are done in a Commodore-compatible way, meaning that the overall API is the same as is the command sequence to open/use/close a device. It supports IEC devices 4-31, and I've successfully used both printers and disk drives with the SBC-2.

Additionally, the code contains a DOS command interpreter module which sort of looks like and operates like the disk commands in PET BASIC 4.0. Not all commands are supported, but enough are that it's convenient to use.

IIRC, the entire Serial IEC support module is just over 3k in size.

Rich

I tried all the firmware versions on my 6502SBC 2.7r1 that include the DOS command interpreter (that I know of), but when entering anything, I get syntax errors. I tried LOAD, SAVE, LIST, etc... Maybe there is a syntax I am unaware of?

[RichCini]

It's been a long time since I've used the board extensively, but the overall command parser is in BASIC itself. My recollection is that it's particular as to how commands are entered (i.e., all caps, no spaces, etc.), but I'd really have to experiment with it again. There have been updates to the BASIC code, but I think my code base was only updated a few years ago.

[tgmaxx]

RichCini wrote:

It's been a long time since I've used the board extensively, but the overall command parser is in BASIC itself. My recollection is that it's particular as to how commands are entered (i.e., all caps, no spaces, etc.), but I'd really have to experiment with it again. There have been updates to the BASIC code, but I think my code base was only updated a few years ago.

First off, sorry my question is off topic from the original subject of this post...

Yes, from within Enhanced BASIC, I was able to get the SAVE command to work, using a Pi1541 drive. I can take the disk and read the files I wrote in Vice. But the LOAD will not work for me. So when I was looking at older versions of the SbcOS, I noticed there is an option for a "DOS command interpreter" that appears in the OS menu, and I thought maybe it is a lower-level interface to DOS commands, perhaps outside of BASIC. There is a > (or *) prompt like the normal OS prompt. So I tried various DOS-type commands and only get "syntax" errors. So that was my question, is it possible the save and load commands might work there? Thanks for your assistance!

[RichCini]

No they won’t. I believe when I coded the DOS interpreter I used DSAVE and DLOAD similar to the Commodore DOS that it was modeled on. The regular Save and Load was supposed to work with the simulator on which the sbcos originally ran on. But, I confess, I’d need to trace through the code to be sure.

[tgmaxx]

RichCini wrote:

No they won’t. I believe when I coded the DOS interpreter I used DSAVE and DLOAD similar to the Commodore DOS that it was modeled on. The regular Save and Load was supposed to work with the simulator on which the sbcos originally ran on. But, I confess, I’d need to trace through the code to be sure.

Ok thank you Rich. I have enough info now to dig into it. And I will further check Daryl Rictor's load and save code as he describes here:

viewtopic.php?f=5&t=2198#p19867