General Stuff(tm)

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rubber_jonnie
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Re: General Stuff(tm)

Post by rubber_jonnie » Sun Oct 10, 2021 11:38 am

@stephen_usher Good luck for today,I hope it all goes great :)
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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PhilC
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Re: General Stuff(tm)

Post by PhilC » Sun Oct 10, 2021 11:38 am

@rubber_jonnie that looks interesting but I'd not have a clue what to do with it. But ott just gor a clock.

BTW, apologies I didn't make it yesterday, glad to see you had a good day though.
If it ain't broke, test it to Destruction.

stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher » Sun Oct 10, 2021 5:40 pm

Today went well.

This was the Atari display:

IMG_2434.jpg
IMG_2434.jpg (385.59 KiB) Viewed 253 times

Lots of interest about the TT and Spectre GCR and a few about the CPU switcher/TF536.

This was yesterday's display.

Image.jpg
Image.jpg (331.22 KiB) Viewed 253 times

Now I'm going to have a relaxing evening and an early night in the hotel and drive home after rush hour tomorrow.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: General Stuff(tm)

Post by stephen_usher » Mon Oct 11, 2021 1:50 pm

Home from Cambridge and everything dumped out of the car and into the living room.

Time to have a little sit down before the big push to move stuff into better locations. Knackered.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

Badwolf
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Re: General Stuff(tm)

Post by Badwolf » Mon Oct 11, 2021 2:23 pm

stephen_usher wrote:
Sun Oct 10, 2021 5:40 pm
Now I'm going to have a relaxing evening and an early night in the hotel and drive home after rush hour tomorrow.
Very good, Stephen.

Good security arrangements too: if anyone looks like they might pinch any of your gear, you just beat them to a pulp with the MTX500! :lol:

BW
Falcdate Use the internet to work around dead Falcon NVRAM battery
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
DFB External 030 and AltRAM for the Falcon (under development)

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Re: General Stuff(tm)

Post by stephen_usher » Tue Oct 12, 2021 10:51 pm

Hehe.

Well, tonight's escapade has been finishing putting all the exhibition stuff away and then looking at the Spectre GCR cartridge to see why it doesn't work on the TT.

Well, there were a few very poorly done bodges on the board, reverting it to stock from what looks like some sort of test using a 74LS04 piggy backed on another of the chips but only connected by VCC and GND with a resistor and capacitor connected to various legs. Three traces on the board were cut and there are blobs on some other chip legs. I'm wondering if it was a delay for a pulse. The bodge wires on top were great loops of wire, one soldered to a pin on a chip and the other end to the cut trace. I had to fix it as one wire had come free. The bodge wire on the underneath was less poorly done but it was still very long.

Anyway, I removed the two top bodge wires and replaced them with a couple of neat ones underneath. I also noticed that the ground plane around the outside of the PCB wasn't actually connected to ground, so I fixed that.

Still, it still doesn't work on the TT. The pulses from the chips look to be doing their thing. I'm wondering if the Mac ROMs are too slow and aren't being read correctly so the "Mac" is crashing with corrupt images in memory.

P.S. I did notice that the two Mac ROMs I have seem mismatched. One looks to be a rev B and the other a rev C. Maybe this is causing a crash on the TT as it's using code that is changed which the ST doesn't use.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher » Wed Oct 13, 2021 9:24 pm

I had a look at the Spectre GCR cartridge again this evening, more out of interest with regards to what the TT's address bus looks like at the cartridge port and other voltages.

Well, the +5V is flat with just a small amount of spiky noise, so that's one thing ticked off any possible problem with this cartridge and the NetUSBee. The voltage is very slightly high at 5.04V but what's 4 hundreths of a volt between friends?

However, the address bus is more interesting, and seeing all cartridge stuff uses the "write using reads" trick this may be playing a part in the problems. This is a typical trace from any of the address lines:

IMG_2437.jpg
IMG_2437.jpg (77.45 KiB) Viewed 153 times

As you can see, the address lines are ringing quite badly. The bus really could do with some terminating resistors to damp the oscillation, possibly in combination with some small value capacitance to kill the high frequencies.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

Tomswork
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Re: General Stuff(tm)

Post by Tomswork » Wed Oct 13, 2021 9:36 pm

Interesting it's like there is a extra length of wire on the bus


Tom

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Re: General Stuff(tm)

Post by stephen_usher » Wed Oct 13, 2021 10:19 pm

The data lines are worse...

IMG_2438.jpg
IMG_2438.jpg (76.34 KiB) Viewed 139 times
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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rubber_jonnie
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Re: General Stuff(tm)

Post by rubber_jonnie » Wed Oct 13, 2021 11:15 pm

Is this at the cart port or on the cart itself then? Does it work in an ST? I'm not familiar with the TT, is it like the Mega STE in that clock speed is adjustable, and if so does a slower clock speed make a difference?
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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