Sharp MZ-700

[jay_oldstuff]

Hi all does anyone have any experience with the above micro. I got one many moons ago but without any software so stuck it in the attic. I refound it the other day and after a bit of a search on the web found this site http://www.sharpmz.org/ from which I was able to download some software, namely Basic and a couple of games. managed to convert them to wav files which I've recorded down to cassette. The computer boots to its line editor (no basic in rom on these) typing L and pressing enter prompts you to press play on the internal tape player but the tape just plays to the end with no indication its trying to load, no noise no prompts on screen nothing. so i tryed again but this time playing the WAV file from my laptops headphone out into the tape input on the rear of the computer. just the same.
So far the only repair i have done to the machine was to replace the two Rifa branded X2 caps in the PSU as one went pop as soon as I showed it the mains.

Jay

[SteveCG]

I don't know this micro - but didn't cassette recordings for micros use a 'modem' type of modulation? That is, the digital information was encoded using a modem (usually built into the micro) and then recorded on a standard cassette recorder. The playback was then decoded by the micro and loaded into memory.

[jay_oldstuff]

Basically yes, I have software on the PC that converts MZF files which are a digital coding of the original MZ-700's tapes back to a WAV file so it can be recorded back to tape or played from the PC's sound card I have done this previously with a number of other micros like the Sinclair spectrum and acorn electron with grate success. with all other micros I've played with you get some sort of indication that something is loading.

Jay

[G6Tanuki]

Not sure about this specific micro, but the pretty-much standard encoding for hobbyist data-storage-on-cassette was a modified "Manchester" NRZ self-clocking encoding (no need for a separate clock-track as the clock could be recovered either by a PLL or a software-emulation thereof) often known outside the UK as "Tarbell" after Don Tarbell who invented it. I met him once.

It then became popularised as the "Kansas City Interface"; http://en.wikipedia.org/wiki/Kansas_City_standard

The big issue with using consumer tape-recorders always seemed to be that the automatic level control often screwed-up: you could try re-recording your tape with different volume levels [and also sometimes the 'bias' setting needed experimentation with: just because you were using a 'chrome' tape didn't mean you needed the chrome-bias setting!] "Computer" tape-recorders often bypassed the ALC for recording.

[jay_oldstuff]

what about the direct input method. the MZ-700 has cassette in and out on the rear as well as the inbuilt tape player. on my 48K spectrum and dragon32 I connect my laptops headphone output to the computers tape in and can load software from WAV file without issue. with the MZ-700 I get no response.

[julie_m]

It should be possible to write a little program (about 50 bytes) in the Sharp machine code monitor, to show the state of the cassette input port pin in real time. That will help you work out whether the problem is in the analogue or digital domain.

[acollins22]

Hi Jay,

I have one of these and last time I used it I used a cassette adapter plugged into my PC playing WAVs (I didn't spot the direct input )

I don't remember any special treatment being needed.


Andy.

[jay_oldstuff]

Thanks for that Andy can you recall weather you get any audible or viable indication that the program is loading?

ajs_derby That sounds interesting unfortunately my knowledge of the sharps machine code is nill and as of yet ive been unable to locate a copy of the owners manual for this machine.

I think i need to find the service manual before i can go much further with this.

Jay

[gary_crutchley]

Hi there,

I'm afraid that I can't help with this issue, but I did have an MZ-700 when this computer first came out, indeed I still have it somewhere in the loft in it's original box. I haven't powered it up for years, but spent ages on it programming in BASIC when I first had it.

Happy memories, I hope that you get it working.

Regards,

Gary

[julie_m]

Originally Posted by jay_oldstuff

ajs_derby That sounds interesting unfortunately my knowledge of the sharps machine code is nill and as of yet ive been unable to locate a copy of the owners manual for this machine.

I think i need to find the service manual before i can go much further with this.

If you find some documentation for the MZ-700 online, and it makes mention of the machine code monitor program, give me a link; and I'll see if I can't code up a cassette port test program if there isn't already a working example to use. (I'd need to know the I/O port address and bit assignment for the cassette port, and the address of the ROM routine -- or, since it's using a Z-80 processor, it may be a RST point -- to display a character on screen. That information is just stuff that would need to be in any programmer's manual.)

[Courtney Louise]

I have one of these with a Rom Cartridge for Basic and a couple of other carts, can't remember what's on them though, more of an Acorn/Apple person tbh.

[acollins22]

Originally Posted by jay_oldstuff

Thanks for that Andy can you recall weather you get any audible or viable indication that the program is loading?

I'll set the machine up this weekend if I get a minute and try it again for you.

Cheers,

Andy.

[jay_oldstuff]

Originally Posted by ajs_derby

If you find some documentation for the MZ-700 online, and it makes mention of the machine code monitor program, give me a link; and I'll see if I can't code up a cassette port test program if there isn't already a working example to use.

I have so far found this link http://www.manualslib.com/products/S...0-3069697.html where you can download the basic manual and the service manual, I'm hoping the service manual may shed some light on the situation.

Jay

[acollins22]

Hi Jay,

I've got the Sharp out of the cupboard and fired it up...
I'm using HU-BASIC.wav on my phone and a cassette adapter.

I get the monitor first and type L
It asks me to press play on tape.
I start the WAV playing and I see "LOADING HU-BASIC V1.3" and it loads to completion with no other output.
If I stop the WAV part way through I get an error.

Hope this helps.


Andy.

[jay_oldstuff]

That is fantastic Andy many thanks at least i now know what it should be doing.

Jay

[julie_m]

A quick scan through the service manual suggests I might indeed be able to find sufficient data in there to write a cassette diagnostic program.

I will take a more in-depth look later .....

[jay_oldstuff]

Wow that would be awesome if you could, I wouldn't know where to start. I can program in basic to a modest extent but that's about it.

Jay

[jay_oldstuff]

It's working😊 I downloaded a copy of hudsen basic converted it to a wav and wrote it to a cassette. And it loaded so tried again with a small game program and again it loaded. The only difference is the cassette recorder I used. Firstly I'd been using a rather top quality Sony mono cassette recorder late 80'a vintage and my go to machine when loading up software in my vintage computers. This time however I grabbed a early 80's recorder (one of the ones with computer comparable embellished across the top) it's very well used and not the best quality but both recordings off this machine loaded without issue. I did try loading both direct from the laptop into the cassette port on the sharp but no go with that. At least the internal tape is now proven.

[acollins22]

Well done Jay that's cracking news.

Andy.