RetroChallenge 2017/10: Part 2

An NEC PC-8401 Quick Guide Book for the Internet Archive

As we know from the previous blog entry, there was absolutely no documentation on the NEC PC-8401BM contained within the Internet Archive. Today I thought it might be a good idea to start addressing this situation.

PC-8401BM Manuals

I have in my possession the 4 Australian Manuals and the Quick Start Guide originally packaged with the PC-8401BM. The easiest of these to scan and make available to the Archive is the Quick Start Guide, this being the only book conveniently with a ring style binding. So naturally I've started here.

Being in a spiral binder the pages were easy to remove, this has allowed for quite a nice scan overall. The other manuals however are going to be slightly more of a challenge to pull clean copies from. So after an hour or so plus some cleaning up time, I'm happy to report the Quick Start Guide is now available to all those who seek it's wisdom.

I should say the Guide is mostly available, there are unfortunately 2 pages missing, pages 34 and 35. These pages should form the first part of the Calc-To-Go section in the book. Not the best of situations, still the rest of the book is complete and pretty much gives all the information the casual PC-8401BM user is likely to require.

I'm not quite sure on the best way to proceed in scanning the remaining books. All the manuals are in exceptional condition, as such I don't wish to ruin them by either pressing the books to firmly against the scanner and cracking the spines, or indeed by removing the spines. It certainly would be handy to have access to a book scanner. (If anybody out there is feeling generous, please send your best book scanner free of charge ASAP).

As a bonus, I thought I'd clean up one of the pull out / fold down sections of the Guide illustrating the many extended devices NEC produced to dock and otherwise attach to the PC-8401BM. These include Data Recorders, Disk Drives, RAM Cartridges and CRT / Monitor adapters. The product codes of all these items is conveniently listed. For those interested in acquiring computer extensions today, the NEC product codes it could well make Ebay and Craigslist searches a little easier (you could try NEC directly in some sort of vain last hope of course).

The PC-8401BM Connection of Peripherals fold out, because everybody loves a good diagram.

The Guide Book is now avaliable and indexed at the Internet Archive: https://archive.org/details/NecPortableComputerPc-8401bmQuickGuide


See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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Think Different, the TRS-80 Model 100

And now for something completely different, the first articles (along side the usual stuff) based around the portable computing powers of the TRS-80 Model 100. Yes I'm jumping to the right for a look into something not Sinclair related, though not I think not without some correlation. On first glance there is not a lot to connect the cheep yet stylish Sinclair home micros to what could best be described as an 'American Design' (baring that internals are all Japanese) beige business mans machine.

TRS-80 Model 100 With the Full Kit.

Yet, initial target audience aside, the Model 100 seems to be something outside the a strict business box, it feels more like a portable home computer, with its Micosoft Basic interpreter and built in rudimentary applications. This is not a computer designed to run CPM and Visicalc, not straight from the factory at least, this is a computer that if one ignores initial hefty sales price tag, would have appealed to any home enthusiast of the period. One just has to glance at the included manuals to see that, in particular the Technical Reference Manual.

Yes the Technical Reference Manual, a 127 page thesis on the entire design and construction of the Model-100, this is an 80's hardware hackers dream. The guide presents the full schematics, lists every single part used in construction (with catalogue numbers) and even goes right down to LCD screen design.

The hardware itself is by no means shabby, the Model 100 packs in a modem, full serial and parallel ports, a very clear LCD display and a fantastic full sized mechanical ALPS keyboard. All these features of course contributed to the high price point of the little portable back in 1983. Equally, these features make the model 100 a very interesting and usable(?) machine today. The Model 100 is the perfect kind of micro for some modern experimentation.

All good stuff, however I need to get down to some quickly required (non business) business.

A little Leaking Battery Work Required

I picked a Model 100 very recently, one in excellent condition, this machine seemed well loved (and used) by its former single owner, and included where all the original manuals and documentation. What it did need was a good clean and a new internal battery. Yes is the old leaky soldered-in NiCd battery curse of old computers. 

The Model 100 uses a NiCd battery to keep 32K of static RAM juiced up when the computer is powered down. The battery is rather important as the static RAM is the internal storage medium, there are no flash drives in thid machine. While the battery was still holding charge, it had began it's decay, and had started leaking ever so slightly. Time for a replacement.

Leaking NiCd Battery

A little googling revealed an interesting replacement idea for the battery, suggesting the use of a super-capacitor. This seemed like a perfectly reasonable proposition, and so I took the advice and installed and 1 Frand super-capacitor. If doing this mod yourself, As noted in the original source, insure the 1 Frand super-capacitor used is rated 5 VDC or better.

1 Frand Super-Capacitor Battery Replacement

The replacement procedure it simple, remove the old NiCd battery, solder some wires to the circuit board and attach the capacitor. With Super-capacitors, polarity matters, so be careful to attach the negative anode to the negative wire / solder pad and positive anode to the positive pad. I bent the pins of the capacitor over horizontally before attaching wires, and hot glued (generously) the capacitor to the circuit board to keep it secure.

After putting the case back together I left the capacitor to change for a while, tested that if all external power was removed that yes the 32K static RAM would stay active. No more leaking battery and no more memory worries.

Now it's time to see what else we can do with this beast.

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