Time capsule(s)

I've just bought for £7 a complete Sharp PC-1251 with its CE125 base unit with micro cassette and printer - it was all wrapped up since 1983. I have to say in all my 35+ years in IT I'd never seen Basic Programs stored as a .wav file. When you play them you get the shrill sound reminiscent of 80s Spectrum and Modems. When played it imports the actual basic program! I've also got a vintage Commodore PR 100 programmable calculator which just needed a new rechargeable battery, I replaced the internal battery with a new pack normally used in a Tomy baby alarm. What I can't find is a printed manual for the PR 100 or more importantly a DC ADAPTOR - the original one for Europe was model number 708, which again I can't track down. It was a 6v DC output via a female Jack - does anyone know if there is a modern replacement psu please.


  • Great find on the Sharp!

    Strangely, yes, I've been using BASIC programs in WAV form. I can recommend NOT using a cassette recorder to play them. Instead load your WAV into you mobile phone and plug the headphone jack right into your device.

    I have a PR100 somewhere. not sure if i have a manual. probably not. but it's a nice calculator.

  • I find it somewhat odd to consider using millions more transistors (and a lot more computer power) to reproduce the sound in the .wav file than in the computer that will finally run the program. So I'll stick to my electromechanical tape recorders (which still work extremely well). My cellular telephone doesn't play .wav files as far as I know anyway.

    A word of warning, though. If you put the 2-contact (mono) jack plug of the typical computer cassette interface into the 3-contact (stereo) headphone socket of your 'phone then you will most likely short the right hand channel output to ground. Whether this will damage the amplifier in the 'phone I don't know, but I wouldn't want to risk it. Make up a special adapter cable or something.

    I don't know this Sharp model, but some of them had excellent technical reference manuals available that documented the processor instruction set, useful ROM calls, etc. I have the manuals for the PC1500 and PC1350 on my shelf.

    Can you describe the connector on the Commodore PSU? Is it a normal jack plug, one of those coaxial power connectors (that used to be called Motorola plugs when I was young) or what?

  • It was also marketed as the TRS-80 pocket computer PC-3. The connector is a small hole in the top of the calculator so I'm assuming the 6v DC PSU has the equivalent male plug. I do have a PSU with 10 different connectors but not one of them fits, they are either too big or too loose. I think it's positive tip

  • Its called ADAPTOR 708 6v DC positive on centre Forgot to say that the Sharp comes with a cable that links the 1251 to an external tape cassette player.

  • I am confused as to which machine you are looking for the mains adapter for. I assumed it was the Commodore, but one of the messages suggests it's the Sharp.

    The TRS-80 PC3 is one of the few I don't have the service manual for (Tandy/Radio Shack sold service manuals for just about everything, even things they re-badged). I do have said service manuals for the PC1 (Sharp PC1211), PC2 (almost the Sharp PC1500, but watch out!), PC4 (Casio FX710 I think) and PC6 (later Casio something-or-other). I think you can get them from archive.org.

    As regards the Sharp tape recorder cable, I am guessing the tape recorder end (if not both ends) have 3 jack plugs (2 off 3.5 mm for saving (Microphone socket), loading (Earphone socket) and 1 off 2.5mm for remote control). Each plug has 2 contacts, known as tip and sleeve. A modern cellular telephone, MP3 player, soundcard, etc is likely to be designed to work with stereo headphones, using the plug that was introduced with the first Sony Walkman. This has 3 contacts (tip, ring, sleeve). If you compare the 2 plugs you will see that the sleeve of the 2 contact plug also occupies the position of the ring on the 3 contact one. If you put the 2 contact plug in the 3 contact socket then the ring contact on the socket and the sleeve contact on the socket will both connect to the sleeve of the plug, in other words they will be shorted. This may or may not do damage to the cellular telephone, etc. Well-designed units should stand it, poorly designed ones (which may be expensive models...) may not.

  • Hugh the inbuilt mini cassette recorder works absolutely fine reading and saving programs, I haven't had time to try an external tape recorder yet. As the cable from the CE-125 goes straight into external recorder (the manual says use the ear or mic socket) then I could also my reel to reel Sony Tape Recorder or even a minidisc player?

  • On the Commodore PR-100 Well I've made a charger by using an old USB lead, cutting one end off and soldering a mono Jack plug on the cut end and then into an USB mains charger; this works a treat and seems to measure 4.5v DC output. I believe that is right as I found an article which said that if I replaced the internal battery pack (which I have done) then I should stop using the 6v charger and use one with 4.5v DC. Anyway it works, it now recharges and no signs of smoke yet!

  • The pr-100 is a nice calculator. It's cheaper cousin, the P50 often pops. inside there is only 1 chip. The p50 has only 24 steps which rather limits programs.

    It took me 27 years to figure out how to fit a NIM game into it. http://www.voidware.com/calcs/p50.htm

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