Yes, the difficulty with serial is that it's a continuous stream rather than a file system - so we'd have to implement some protocol on top of it to transfer files. I've had a little success using the built in serial port to transfer files from a laptop (slowly), but there's no way of choosing the files from the EP end, and it never knows when the file ends.

However, there's probably already an xmodem client for CP/M or something like that.

You are absolutely correct!

The problem of transferring files across a serial link was solved back in the 1980s/1990s, but we have just not had a reason to use those old solutions on the Enterprise, yet.

There are already CP/M versions of XMODEM, ZMODEM and KERMIT file-transfer programs.

There is the classic CP/M communications program ZMP, and a modern port of ZMP using the latest Z80 version of HiTech C.

There is a modern version of KERMIT called E-KERMIT which can probably be compiled for the Enterprise using SDCC.


The PC side of any file transfers can use TeraTerm or PuTTY on Windows, or minicom on Linux.


All of that software is already written, we just need to either configure it, or build it, for the Enterprise.

That does not mean that it will be trivial to get working, but it is not like we are starting with absolutely nothing.

-  Is it possible to use only the usb expander without memories? (I already have 1 GB built-in + SF3 + FDD interface)
- The amount of shipping cost should be added to the calculated price. (I think.) How much would it be?

This board connects to the Enterprise motherboard's EXP1 and EXP2 connectors, and so I don't believe that you could use it with your current 1MB expansion board, you would have to replace that board with this one.

Shipping from the USA to Hungary for my other memory boards has cost about $17 USD (approx 5,100 HUF).  If a lot of people were interested in this board, when it has been manufactured and we are sure that it works correctly, it might be cheaper to send all of the boards in one package, and then have someone in Hungary distribute them out to everyone.

That's what I undertake.

I have seen similar solutions, the best one is the ZX Spectrum Interface 1 Bis, a modern approach to the Microdrives... as partitions on a micro-SD.

Cool, I didn't know that someone had done that for the Spectrum!

I am more familiar with other projects that do the same kind of thing, such as DriveWire for the Tandy Color Computer, and RespeQt for the Atari 800.

Something like those could also be done on the Enterprise, but you would really want to integrate it into EXDOS, and it would be a lot of work that I am afraid might never be done, especially since you would have to be careful not to break the existing versions of EXDOS that people use for floppy discs and the SD Card adapter.

It wouldn't be fair for me to get people's hopes up about that, because it is not something that I am personally interested in working on. It is far more than I need or want.

Writing a small program to transfer a file across the serial link, and then use an existing EXDOS ROM to save it to floppy/SD is *much* easier to develop, and much more likely to get completed because it is a manageable project.

Something like those could also be done on the Enterprise, but you would really want to integrate it into EXDOS, and it would be a lot of work that I am afraid might never be done, especially since you would have to be careful not to break the existing versions of EXDOS that people use for floppy discs and the SD Card adapter.

Don't worry about breaking EXDOS... it stands for EXpandable Disk Operative System. In fact, the SDEXT.Rom is a driver extension to integrate the SD on the system, and there is even an IDE driver, also written by Zozo.

But there are other imaginative ways to add file management to the Enterprise, for example the FILE I/O driver that IstvanV uses on the emulator to manage a PC directory, and the "tunnel" like driver used by Geco on the SF3. They work even on a Tape only Enterprise(without EXDOS), managing the default device of EXOS. I name them tunnel drivers because they are able to manage the unknown format on the PC drive or a FAT32 formatted pen-drive, transparently to the user.

A file transfer manager will be an excellent start for your USB port, but please, leave the hardware well documented just in case...

Great. Have you looked at LGB's Z80 ports list?

Since the time he created the list, other hardware have taken position, for example, SF3 uses 20-2F and 40-4F ranges(incompatible with the Spectrum Hardware emulator).

I see you use F8h and B8h as communication ports. Good selection, single unused ports, but you must re-assure that these are not mirrors ports of other nearer ports, from the RTC card or Dave.

Usually, a wealthy EP returns 255 from an unused port(for example "PRINT IN(XX)"  ), but I don't know how to test a port on Output.

I see you use F8h and B8h as communication ports. Good selection, single unused ports, but you must re-assure that these are not mirrors ports of other nearer ports, from the RTC card or Dave.

I suspect that you have misunderstood what I wrote ... which is a very easy thing to do when we're both relying on Google Translate!

The two USB hardware port addresses are not mapped into the Z80's I/O Port address range, because the Z80's /IORQ signal is not available on either EXP1 or EXP2, and frankly even if it was, there are not enough pins on GAL16V8 to map both RAM segments and I/O ports.

The USB hardware occupies a 64KB region in the Enterprise's 4MB memory map (i.e. 4 segments) ... which is why I have to be careful that the EXOS scan for RAM/ROM segments will not harm the USB chip.

Using a whole 64KB region is somewhat wasteful, but we can afford the memory space, and it is the best solution that I could think of actually building something that is both affordable and easy-to-install.

so the different status, and data registers are equivalent, and i can use ex status register 78:0000 and data register 78:0114 for reading/writing the data (i know it does not make sence, because in this way the operation is slower), because a0 - a7 are ignored.

I suspect that you have misunderstood what I wrote ... which is a very easy thing to do when we're both relying on Google Translate!

The two USB hardware port addresses are not mapped into the Z80's I/O Port address range, because the Z80's /IORQ signal is not available on either EXP1 or EXP2, and frankly even if it was, there are not enough pins on GAL16V8 to map both RAM segments and I/O ports.

I thank you for the care with which you have answered my ignorance...

I usually read too fast without reasoning and that creates imperfect conclusions.

Now, re-reading your messages, I can(slowly) understand the mechanism. Yes, you don't have /IORQ directly.