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1980s_john

Microwriter MW4 notes

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I'm in the process of working on three of these, bought over a couple years on eBay. There is a description of the MW4 on the Wiki page, which I will add to once I have made enough progress.

First thing was none of the units came with power supplies, they run off 4 NiCd cells (20mm x 40mm each), via a drop down resistor. I am using a 9V regulated supply, and later on will try out some unregulated ones. Once charged the NiCds hold the voltage to around 5.6V (4 x 1.4V).

The connector is a DC power plug, size is 5.0mm outer diameter and 2.5mm inner diameter, tip negative / sleeve positive (opposite way round to the norm). The plug I have (like most on sale) is 9.1mm long, this only just reaches, and on one MW4 the plug falls out, so I have some long reach (14mm long) plugs on order which hopefully will be a better fit.

Once the battery has changed the unit can be switched on, I was lucky as all mine responded to the keyboard straight away.

The best site I've found on learning to the keyboard is

http://memorize.com/cykey

The manuals are finally on the web, thanks to Bill Buxton (and oddly enough Microsoft):

http://research.microsoft.com/en-us/...tail.aspx?id=5

(I haven't fully explored his site, but any VCF fan is bound to find something of interest there.)

Having learnt the alphabet (then 0 to 9 and basic punctuation) the next thing are the commands. These are explained in the user manual but basically there are two groups of commands - shifts to change the characters entered on the keyboard for the same finger pattern, and word processing commands to delete, add tabs, change printer baud rate etc.

One key command I needed was to reset the settings; 'as is' my Microwriters powered on with a line length setting of 0 or 1, which resulted in the display locking up every 8 characters - very frustrating and without the manuals I would have given up trying to fix it.

The LCD display contrast is adjusted using a variable resistor on the PCB near the display.

I have some new NiCds on order, these are 4/5 C cells which measure a bit shorter than the original cells but should work fine.

The bottom of the unit has a 37 pin connector, this appears to be an expansion of the microprocessor bus. Top of the unit has a 3.5mm audio jack to connect a cassette recorder - I haven't tried this yet.

There is also a 25 pin D type connector on the top of the unit, manual says this can be used to connect to a printer (RS232 serial), and also to an accessory called the 'Display Screen Adapter' or DSA. I have one of these (came with the last MW4 I bought), it has four connectors, power, video out and TV out (UK spec UHF modulator), and a 9 pin D type. The power socket is the same as the MW4, and when I plugged it in I got a random assortment of characters on the TV (16 lines of 64 characters) - wonderful!

Next problem is working out the cable to go to the MW4. The Microwriter has to be in a 'display out' mode rather than a 'use printer' mode, and when in display mode the 25 pin connector stops being a RS232 interface and becomes something similar but not quite. I have a RS232 break out box and all I have worked out so far is that pin 5 from the MW4 is some form of signal, and most of the DSA pins are inputs - using a pair of wires results in a blank character being continuously written on the TV - I need to analyse what is going on.

In summary an intriguing device, with more features available than a quick glance would lead you to believe.

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