My Spectrum +2 (grey case) was working great with a DivMMC. Then recently it would take a couple powercycles for DivMMC to boot into ESXDos. Today I get nothing but a garbled pink screen when using it with the DivMMC.
When in this state the reset buttons on the +2 and DivMMC also don't work. When I remove the SD card the spectrum works as normal. I tried a different SD card but got the same result.
[BTW: The bottom of the screen is cut off because this is USA TV]
Any pointers on how to diagnose what has gone wrong?
Have you cleaned the edge connector? If yes, describe how you did it.
On the female edge-connector socket on the DivMMC, is the locating peg still present?
Without the DivMMC connected, does the machine work okay with both the 128K BASIC editor (can you enter and run a simple ‘hello world’ program) and with machine code games loaded from tape (or another suitable audio source)?
With the DivMMC connected, but without the SD card inserted, does the machine work okay with both the 128K BASIC editor and with machine code games?
Do you have another suitable working ZX Spectrum to try the DivMMC on?
The reset switch on the machine resets the Z80 CPU (and also the chip that controls the banked memory). The screen picture that you posted indicates that it is likely that the Z80 CPU is either not running, or it is executing random data instead of running the code in the ROM. On power up, or immediately after the reset button is released, the Z80 CPU should run the ROM code from memory location zero (0x0000). Anything that prevents the Z80 CPU from running the ROM code could be causing this. When a DivMMC is connected, the Z80 CPU will also try to run the ROM code in this device.
The ULA in a ZX Spectrum generates a display image regardless of what the Z80 CPU is doing (or not doing), but if the Z80 CPU has not written any data to the area of memory where the screen data is located, the ULA will display the data it finds there, which will be random data. Alternatively, in some cases, if the Z80 CPU is running random code instead of the ROM code, it may trample over the screen memory area writing garbage data.
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
I cleaned the edge connector with a Q-Tip and Isopropanol Alcohol.
Yes the DivMMC connector has the locating peg installed.
Without the DivMMC connected the spectrum works fine and has had a good hour of play time.(Where Time Stood Still, Rodland, Nosferatu) I can load games from tape and the mic socket. The editor works too.
Yes with the DivMMC connected and no SD card it works perfectly.
I don't have another Spectrum or any other hardware to test on. The DivMMC was working up until recently.
Okay, so as far as I can see, there is nothing wrong with your ZX Spectrum +2.
Do you have another SD card to use with your DivMMC? If yes, try this, as it may simply be a corrupt file on the SD card.
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
I tried another SD Card and also used the formatting tool recommended on the TFW8b.com website. Additionally I tried the older version of ESXDos 8.7 and 8.6, same result with on all fronts.
I'll email TFW8b.com again, perhaps there is an issue with the DivMMC.
I got a very quick reply from TFW8b.com and they suggested reflashing the DivMMC. Something I didn't think of or realize could be done when the system wasn't working.
It all works now!!
To Reflash:
1, Pop out the SD Card, but keep DivMMC attached.
2, Load the Flashing Tool which is a .WAV on the SD Card into the Spectrum.
3, Wait for the screen to stop changing colours while the flash happens.
4, Insert SD Card... Success.
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Standby alert 
