General Stuff(tm)

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rubber_jonnie
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Re: General Stuff(tm)

Post by rubber_jonnie »

@stephen_usher Good luck for today,I hope it all goes great :)
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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PhilC
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Re: General Stuff(tm)

Post by PhilC »

@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.
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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

Today went well.

This was the Atari display:

IMG_2434.jpg
IMG_2434.jpg (385.59 KiB) Viewed 2137 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 2137 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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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

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.
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Badwolf
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Re: General Stuff(tm)

Post by Badwolf »

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
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

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.
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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

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 2037 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 »

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


Tom
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stephen_usher
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Re: General Stuff(tm)

Post by stephen_usher »

The data lines are worse...

IMG_2438.jpg
IMG_2438.jpg (76.34 KiB) Viewed 2023 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 »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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