PCEmon - how to backup/restore backup memory

[dshadoff]

Actually, PCEmon is straightforward... but I found that I encountered a bunch of startup questions, and I'm attempting to resolve them here for anybody else who might have the same questions.


Step 1: Get a USB-to-FTDI adaptor rated for 5V, in order to make the cable.

I used this adaptor:
www.amazon.ca/DSD-TECH-SH-U09C5-Converter-Support/dp/B07WX2DSVB/ref=sr_1_1?keywords=B07WX2DSVB&qid=1571587391&sr=8-1

Wiring a cable can be a pain, but I made a PC board to connect between a male-to-male min-DIN extension cable and this adapter.
It needs two parts:
- female 8-pin mini-DIN connector
- matching socket connector for the FTDI adaptot (I used Preci-dip part #801-83-006-20-001101  which I got from Mouser)


Step 2:  Get Teraterm ( ttssh2.osdn.jp/index.html.en )

Pretty much all of my questions surrounded the PC side of the communications, so start here until you know what's important... then you can use whatever terminal program you like.


Step 3: Put the PCEmon ROM (or hacked system card) onto a flash card.

In my case, I used the direct-boot approach at first, making it so that my PC Engine wouldn't boot to a menu requiring joypad input.  The instructions for this are on Chris' webpages.

The ROM image I used for this (since Chirs' archive includes many versions) was:
(base folder)\19200\TTL.pce


Step 4: Teraterm settings

Plug in the FTDI adaptor and install whatever drivers are required.  My adaptor included a removable "loopback" header to send the output right back into the input, so it can be verified as operational (after the initial check, remove this so that you can access the Tx and Rx pins).

Teraterm won't allow you to choose a serial port to connect to, unless it actually detects that the adaptor is connected and operational.  So make sure this is plugged in and on, before trying to connect using Teraterm.

1) Run ttermpro.exe

2) On the 'new connection' popup, select Serial.  If it isn't selectable, then your adaptor isn't on.  If you have multiple choices, you'll need to determine which of them is the correct port to talk to for the FTDI-to-PCE connection.

3) Most terminal programs have fairly good default settings... but let's verify:

Under Setup->Terminal:
- actually, you will need to change New-line to "LF" (probably "CR+LF" is also OK, but PCEmon requires a LF, so just "CR" is not going to work)
- leave local echo off
- everything else should be OK here

Under Setup->Serial Port:
- make sure that you are on the right serial port
- make sure that the speed matches the speed in the PCEmon version you selected (above, I mentioned I used 19200)
- 8 bit, no parity, 1 stop bit, no flow control (as per default)

I left everything else as-is.

If you haven't yet tested the FTDI adapter and can do a loopback test, you can try now.  You should see the keys that you are typing.  Remove the header and you shouldn't see them anymore.

Otherwise, connect up the PCE side of the connection (with the PCE still off).


Step 5: Turn it on

The PC Engine spouts a bunch of text immediately at startup, and if you connect after it's already on, you will have missed it.  That's why I wanted to have the serial connection up before turning on the PC Engine.

It should then be obvious if PCE->PC communication is working at this point.  If not, check your serial port settings and whether your cable is connecting the right wires (there are only 3 needed, so shouldn't be so hard).

Next, type the cquestion mark ('?')  on the PC, and hit return.  Hopefully another list of text should appear.

- If you saw only the question mark, but nothing happened after that, try typing control-J (that is, while holding the control key down, press the 'J' key once).  If this works but the return key didn't then you need to map the return key to 'LF' (see above)
- If you didn't see anything, you'll need to check your cable again.

Now it's working.  Next post is to grab the backup memory.

[dshadoff]

As I mentioned in post #1, grabbing the memory is easy enough, but you need to be comfortable with the PC side of things, which I will walk through here.

Step 1: Move BRAM to buffer area

Easy.  The command is two keystrokes:  '<' followed by the enter key.
You won't get much of a confirmation though - just another prompt at the start of the next line, waiting for the next command.


Step 2: Output to PC

A little less easy, since it's easy to get more than just the BRAM.  We'll need to control the logfile capture.
The PCEmon side is easy - just 'S' followed by the enter key, after which the PCE sends a bunch of characters (some human-readable, some not) to the screen.
Go ahead, try it now (without trying to capture it).  You'll see.  After it has been sent, just enter enter to get the prompt again. (...well, you might need to hit it twice, but that's OK).

There is another command needed, to stop your keystrokes from interfering in the backup RAM capture file:
OE<enter>
This turns off the echo, so you won't see any prompts, or anything you type after this.

After turning off the echo, go to Teraterm's "File-> Log" menu, and:
- enter a suitable filename and location
- ensure that "Binary" is checked
- uncheck "Append"
- Press "Save"

Now, everything gets logged.  Since you've turned off the echo, it's only the responses to your commands.
Now, we can execute the 'S' command as per above, which will output the buffer to the file.
Once that's done, go to Teraterm's "File -> Show Log dialog" selection, and you will get a new window.  It should tell you your filename and state "Bytes transferred: 2048".  Press the "Close" button.

Step 3: Return to normal

Well, if you want to continue using PCEmon, you'll want to turn the echo back on  with:
'OE'<enter>

And, you'll want to double-check that your file exists and is exactly 2048 bytes.

You can save this on your disk for future, or you can modify it with a hex editor if you know how it wiil affect the gameplay of the game(s) in the file... but that's another subject.

Next post will explain how to restore this backup data back into the PC Engine.

[dshadoff]

OK, restoring the BRAM doesn't need the echo off, but does have a "gotcha".

Step 1: you can leave the echo on.

- no need to da anything, assuming that echo is already on; otherwise, 'OE<enter>'

Step 2: Send Data to the PC Engine

1) the PCEmon command for this will be:
L 0800<enter>
After this, the system will say "Okay, send your binary!"

2) in Teraterm, go to "File->Send file", locate your 2048-byte BRAM file, and - this is VERY important - ensure that the "Binary" option is checked.
If the binary option is not checked, the file send dialog will flash up, then disappear, and you won't know what happened.
Otherwise, it will take a moment or so, and you should at least see a quick progress bar moving inside the popup window.
If successful, you'll see a prompt again on your screen.

3) Now that the data is in the buffer, it's still not stored in BRAM.  You can still abort if you like.  Otherwise, proceed.


Step 3: Commit the data to BRAM

The PCEmon command for this is the greater-than key, '>'  (followed by the enter key).
Again, you won't get a confirmation but it will be done.



Hopefully, this makes people a little more comfortable with PCEmon, and sets the stage for other types of data dumps and save-state manipulation.


Dave

[dshadoff]

Here's a pic of my self-made cable including the adaptor I discussed above... Chris' cable looks less delicate, but this one is certainly up to the task and not fiddly at all.

[ccovell]

Here's my current cable for PCEMon, and a quick way to switch between the TTL mode and controller mode.

[dshadoff]

Nice idea !
You've given me another idea... to make a more compact version of a multi-tap, with an integrated USB communication out, possibly somehow supporting Develo in addition to PCEmon.
...Maybe even with a touch sensor to switch between modes. Sound interesting ?

[ccovell]

Nov 5, 2019 0:22:42 GMT dshadoff said:

Nice idea !
You've given me another idea... to make a more compact version of a multi-tap, with an integrated USB communication out, possibly somehow supporting Develo in addition to PCEmon.
...Maybe even with a touch sensor to switch between modes. Sound interesting ?

Yes, I wish there were some way to switch between controllers / bit-banged serial automatically, but I don't think there is a compatible way to do it with just the 2 output lines (which are both used by games & need to be recognized by the multitap.)

[elmer]

It's great to see those different solutions, especially the switchable multitap-or-comms-link.

But you guys have no chance of luring me away from the Everdrive's super-fast USB link, it's *way* too useful, even without having Chris's excellent PCEmon functionality.

OTOH, you have prompted me to finally buy this ... USB-to-RS232 for Sharp X68000

[dshadoff]

Not trying to lure you away from it... I don't see them in competition. PCEmon brings me back to the old days of bare-metal monitor programs (I started with T-bug on the TRS-80).