A Grand Day Out

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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

HigashiJun wrote: Sat Feb 10, 2024 9:04 am
rubber_jonnie wrote: Sat Feb 10, 2024 8:51 am I don't, no. I don't feel compelled to get one either, at least not like some other machines.
Yeah, same here...

I cannot explain why, but I'm more attracted to some machines than others.
For me it is mostly about the machines that were about when I was young, starting with the ZX81 as my first computer. And a few other interesting ones...
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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HigashiJun
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Re: A Grand Day Out

Post by HigashiJun »

8-)
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

OK, so it looks like I've misunderstood how the external cassette interface works. Thankfully a side conversation with @PhilC may have set me straight.

Going through the schematics the external input actually doesn't connect via the internal cassette, though it does go to the same 9 pin plug on the mainboard the internal cassette uses.

Phil suggested that he thought it might need to be jumpered in order to connect the external input, so I'm going to connect external cassette 'in' to the internal line on the same plug and see what happens.

Kind of kicks my assertion that the external in went through the amps in the internal cassette, it doesn't, and it is a lesson in paying attention to the schematics.

I had also originally thought that the cassette A/B switched between internal and external, but it doesn't, it just inverts the external cassette input waveform.

Will try jumpering it later and see what's what.
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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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

OK, so first jumpering attempt shows promise.

By connecting pin 2 of the 9 pin connector to pin 8, I am now seeing this signal:

IMG20240211114525.jpg
IMG20240211114525.jpg (212.17 KiB) Viewed 413 times

The blue trace is the input at pin 8, and the yellow trace is at pin 12 of the 8255, so the signal is in fact arriving where it supposed to, and it also is a correct waveform and correct amplitude as expected at test point 6 of the cassette, however there is something else missing.

There is a sense line at pin 5 of the connector and it is connected to the read, write and motor circuits of the internal cassette, but I'm assuming it also requires a connection for the external cassette to work.

There is a switch that connects it directly to ground at some point but I haven't yet figured out when that comes into play, so more digging required.

It's also got some gates and an IC between it and the 8255, so I need to see just what sense does with the internal cassette running.

And as a bonus, here's the cat after he climbed into the bottom of my deskside drawers whilst I had the drawer open looking for cables...

IMG20240211105542.jpg
IMG20240211105542.jpg (190.02 KiB) Viewed 413 times
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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Re: A Grand Day Out

Post by rubber_jonnie »

So, the sense line is figured out, it just needs to be pulled to ground. What it does is tell the Sharp to listen for data as the tape is running. If that sense line is floating then it won't do a thing.

Essentially it's this switch here on the cassette deck:

IMG20240211151339.jpg
IMG20240211151339.jpg (217.79 KiB) Viewed 406 times

Any time any key is pressed, so play, record, ffwd, rwd, this switch is made, pulling sense to ground. In fact the only time it isn't pressed is when the deck is stopped. So I connected pin 2 (ext read) to pin 8 (int read) and pin 1 (ext write) to pin 7 (Int write) so that the external inputs will work.

Since the sense line cannot be made when you execute the LOAD command (I don't know why, probably the sense input being out of order in the load sequence) I still required a switch in order for it to activate at the correct moment.

Well, it turns out that I have just that in the old internal cassette module. All I needed to do was do the ext to internal bodge wires underneath the mainboard, then connect up the old cassette unit and press play on that when I want to load from the external cassette interface.

EDIT: It turns out that LOAD does work at the monitor does load with the sense line connected to ground all the time, so I will likely return at a later date, disconnect the internal cassette completely and just tie pin 5 of the connector to ground permanently.

I verified this here: MZ-700 repairs.

So, does it work? Yes it does, here we can see it's loading Snake & Snake:

IMG20240211143402.jpg
IMG20240211143402.jpg (199.85 KiB) Viewed 406 times

And the final result:

IMG20240211143723.jpg
IMG20240211143723.jpg (234.87 KiB) Viewed 406 times

That's a result I'm happy with for sure.

Next thing I need to pull the keyboard apart, but will do that another day, as the cursor key cluster doesn't seem to be working, though everything else is.

I am going to see if I can find a replacement head for the internal cassette unit, and I need to see if I can find WAV files of the cassettes as so far Snake & Snake is all I can load!! So as yet no BASIC, but the tape does seem erratic during playback.

I will also try my other cassette deck to see if loading improves with that.
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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Re: A Grand Day Out

Post by PhilC »

@rubber_jonnie there is usually a cheap as card solution on eBay for the sharp. I would have probably done it if I was keeping it.

Well done on getting it to load btw.
If it ain't broke, test it to Destruction.
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Re: A Grand Day Out

Post by rubber_jonnie »

PhilC wrote: Sun Feb 11, 2024 5:53 pm @rubber_jonnie there is usually a cheap as card solution on eBay for the sharp. I would have probably done it if I was keeping it.

Well done on getting it to load btw.
Yeah, I'm going to have a look and see what's out there for it :)
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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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

Just for funzies I tried to get another game to load, and it did!!!

IMG20240211200103.jpg
IMG20240211200103.jpg (211.86 KiB) Viewed 381 times

I have to say, I kinda feel like the 2 games I've managed to load seem like they may have been created 'under the influence of substances.'

I dug out my USB cassette player which is the newest cassette player I have and it worked very well, so I may take the time to do a dump of all the cassettes I have just for the sake of archiving. We all know what cassettes are like...

It would also be interesting to see if my Acorn tape deck plays nicely with the Sharp.

Having done the whole 'bodge wire' thing earlier, now I know that the sense pin just needs to be tied to gnd, I may revisit and just make a removable jumper to go inside. We'll see.
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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HigashiJun
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Location: Tokyo

Re: A Grand Day Out

Post by HigashiJun »

Love the picture with your cat !

:D
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

HigashiJun wrote: Mon Feb 12, 2024 1:22 am Love the picture with your cat !

:D
:)
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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