MemoFix 2022

[Dave]

I wonder if these were boards that Jim “liberated” from the factory?

If so, perhaps they failed at the factory test stage and maybe never worked? If that is the case, then it’s not surprising that the “Repair Shop” had problems trying to fix them

Regards
Dave

[1024MAK]

I wonder if these were boards that Jim “liberated” from the factory?

If so, perhaps they failed at the factory test stage and maybe never worked? If that is the case, then it’s not surprising that the “Repair Shop” had problems trying to fix them

The first board I talked about, is from an MTX that has apparently not been seen working. It had us confused, because it will run the diagnostic ROM code. But the VDP ignores writes because the control inputs are in an invalid state (we think).

The second MTX has worked in the past. Jim can tell you the details. It has an internal memory expansion board and a RS232 board permanently connected via soldered (edge) connectors.

Martin, maybe rather than the diagnostic board, try a NOP generator in place of the appropriate ROM, and see if the Z80 will then run NOPs.

Mark

[K8dude]

I was very much looking forward to coming, but had difficulty finding a hotel willing to take my cash rather than government funding.
Will try again next year. Might bring my FDX if there is any need.
Would a Newbrain be if any interest too?

Mike

[1024MAK]

Martin and Jim, there’s some photos I took of the Centre for Computing History, Cambridge here, including both the normal museum area and the room where there was an ABug meet up.

If you’re interested in more information about the ZX Spectrum prototype that the Centre for Computing History was given, there’s three photos here, the museums web page about it here, and a YouTube video here. As I said, if you visit the museum, you can see it with your own eyes, they have it in a display case.

And there was cake.

And the cake was delicious

Thank you Martin for hosting the event again

Mark

[Martin A]

Today was frustrating!

The USB A to A leads arived from Amazon so we had a chance to try re-programming the Gotek.

And

Nothing, Windows identified the Gotek was fitted in programming mode, but the programming sotfware couldn't find the device
As a result we wasted a lot of time getting nowhere.

[Dave]

Martin,

It’s too late now I guess, but was it a “recent” Gotek? With all the chip shortages etc. some of the newer Goteks have different chips fitted, might that be the problem?

Check out the FlashFloppy Facebook group for help flashing the Gotek if needed

Regards
Dave

[Martin A]

It'a an "F415" chip, so is one of the newer ones.

We downloaded the chip programmer from the manufacturer's site as on the flashfloppy instructions (2 versions 1.54 and 2.06) With the jumper fitted windows finds it, neither version of the software does. Will see what that facebook group turns up another day!

[K8dude]

I wonder if there is a comms speed issue going on here? Is the baud rating adjustable in any way to read/write to/from the Gotek?

[Martin A]

I wonder if there is a comms speed issue going on here? Is the baud rating adjustable in any way to read/write to/from the Gotek?

There are speed settings if connectigs via UART, but the USB connetion has no settings at all, I guess it's supposed to identify via plug in and pray.

The various ID fields do appear in the device manager, but not in the programming utility.

[Martin A]

Some more pictures:

The RS96 board:

rear view

1667732180017.jpg (3.7 MiB) Viewed 66736 times

Top view of me checking the continuity

1667732180008.jpg (2.93 MiB) Viewed 66736 times

I'm not sure why anyone would need an MTX with 96k ram, but that's what this one appears to have. It's an MTX500 mainboard, with 2 rows of 32k on the memory card. And it doesn't boot.

It's the board that Mark referred too in his report where the CPU seems to be doing nothing but refresh cycles. Swapping the CPU for a brand new one didn't help.


After a weekend of rumaging to leads or spare parts, the room startedd to look a bit like Aunty Wainwright's

I need to tidy up.jpg (96.46 KiB) Viewed 66736 times

Jim also took some pictures of the wiring mods for the MTX512 S2 just in case we come across another one, or someone wants to try the mod for themselves!