MFX with a difference

[Martin A]

I will add to the list of what can be done, but there's l little use for:

A battery backed, real time clock.

I happened to have some RTC modules for the Arduino I thought I might try and add to MFX. Then Dave pointed out they're 5v and the FPGA is 3v. So rather than give up on the idea, I went out and brought some 3v RTC modules based on the DS3231 and the proper rechargeable battery.

For some reason, they're shipped with the charging circuit enabled, and a non-rechargeable battery. I didn't fancy finding out what sort of pop expolding CR2032's make! Changing the battery was simpler than removing 0603 size components from the charging circuit.

I have managed to connect one, using a couple of the I/O lines from the VRAM socket. As thats basically now an 29 I/O headder, the socket is freed up by the cyclone 4 FPGA that I'm using on the development system. I have some ROM support writen to set/display the date and time, and since it's on the chip the temperature too, and...

That's it.

Until someone converts CPM 3 to the MTX, it's just me showing off, there's no actual use for it!

Having said that Dave, was planning to build an adaptor of his own to give the RTC a go.

[gunrock]

Well, that's pretty cool, however useless it might be!

I saw someone write on a forum just the other day (when someone was complaining about a particular upgrade/feature being a dead-end) and he/she said "Retro-computing is all about dead-ends". Which I thought was apt.

[Bill B]

Until someone converts CPM 3 to the MTX, it's just me showing off, there's no actual use for it!

There is already one use for it. The FATCOPY utility for copying CP/M files into a FAT partition (see section 8.13 of the MFX user manual v1.20) currently has to supply a dummy or user specified date and time for the files it creates. With a RTC it could use the correct date and time of the copy.

Edit:

CP/M 3: How about https://github.com/davidgiven/cpmish ?

Edit 2:

No. CPMish uses ZSDOS which is a CP/M v 2.2 clone.

[Bill B]

If you regard the RAM socket freed by the larger FPGA as an expansion socket, then inspired by Dave Snowden's post, other expansion boards that could be added include:

• I2S sound chip.
• A to D chip
• D to A chip
• Digital I/O (GPIO) chip