Another floppy simulator

[Chuck(G)]

How about an RS232 port header to handle control? That's the way I do my testing now. You could manage the floppy choice from the same machine or a different one.

Remote-control floppy is kind of an interesting.

It would certainly be possible to use a SMT AVRMega, such as the 128. It's not fine-pitch soldering and fairly easy for a moderately-skilled person to do. If I hand-solder the fine-pitch stuff (like the PIC32), I find that an inspection microscope is very important--and probably out of reach of most people's budgets.

 

[njroadfan]

There is a way (in theory) to avoid RS-232 and have a real onboard configuration program that one can "boot" to. Its a bit complicated when the only I/O is the floppy, but it could work (think memory mapped I/O, but with a storage device). It would require a bit of programming for both the onboard controller and 8086 ASM (for the actual configuration program) though.

 

[Chuck(G)]

If you roll back through this thread, you'll see that I proposed something very much like that by generating a fake address header for each track and looking for a read (returns what disk in currently loaded) or write (loads a new disk).

And that's nice, if you have control of the CPU. But if you're in the middle of a program that's asking for a certain disk, there's no way to tell the drive without breaking out of the program.

 

[Maverick1978]

Chuck, if you're asking for opinions on RS232, that sounds like a nice option, so long as it's not a requirement. For my own use, I would much prefer a self-contained unit capable of loading the software using the installed machine, sparing me the need to run two machines side-by-side for what would likely be a day-to-day task.

Weren't you concerned with the AVRMega's performance verses what you could do with the Pic32? Or was it that the AVRMega would do what you wanted, but you would just have more room to grow with the Pic32?

 

[eeguru]

These guys sell a PIC32 TQFP mounted on a PCB with 2x 20 pin .1" headers spaced .6" apart; suitable for a DIP-40 socket. $36 dollars. Might be an option. If availability becomes a concern, just replace it or integrate it directly.

 

[Chuck(G)]

Weren't you concerned with the AVRMega's performance verses what you could do with the Pic32? Or was it that the AVRMega would do what you wanted, but you would just have more room to grow with the Pic32?

It's more expensive both in terms of real-estate and parts to use an AVR than another MCU with integrated memory. A 162 in a 40 pin DIP is pin-challenged--I've literally used every available pin on the package--the external memory takes up 16 of those pins. A 128 has 68 pins, but is SMT (basically it's the same CPU with more program memory). Would that they made these things as a 68-pin PLCC.

For floppies, an AVR running at 16MHz has barely enough horsepower, but it's enough. 20 MHz might be better.

I may have a solution for the selection process. Why not a header carrying +5, Gnd, RD and TD and maybe one other pin brought out on the front of the simulator? You could attach either a level-shifter for RS232 or a small microterminal with just an LCD and a few buttons (probably powered by something like an ATTin2313))? Conceivably, you could even rig your own TTL-level interface.

$35 for a mounted PIC32? :shock: Nothing like enterprise, is there?