This Weekend's Finds

From: John R. Keys Jr. <jrkeys_at_concentric.net>
Date: Mon Aug 18 20:26:16 1997

I can get lots of TI 99 items, tell what you are looking for ??

At 10:28 AM 8/18/97 BST, you wrote:
>> > I bought: A TI-99/4A (Not as lucky as Roger M - I paid L12 with no
>> > joysticks, manuals or cartridges, but I did get the UHF thingy)
>>
>> Nice!!!....
>
>Yes, my first TI computer (I have a broken calculator and a Silent 700
>or two...)
>
>> > But the real find: A British Telecom Microscribe for L1
>>
>> Very nice...
>>
>> > This object is a solidly built sub-notebook (about 7 in square by 1
>> > thick) with a dinky keyboard and a palmtop-sized LCD. It has 32K of RAM
>> > and 16K of ROM, and the processor is an Hitachi HD63A03XP single chip
>> > microcomputer.
>>
>> Is that the only processor? It sounds as though it might be distantly
>> related to a Thorn-EMI machine called a Liberator which had a 63-something
>> for I/O and a Z80 running a CP/M like OS (or at least, that what I think
>> is inside it - the ROM is (C) Digital Research, and running strings on a
>> ROM image turns up some interesting stuff)
>
>'fraid so. Indeed, it is the only chip with >28 pins (apart from the
>flatpacks on the back of the LCD). IC master, just to be perverse,
>gives various 6301 and 6305 variants in that series, but nothing of 6303
>flavour.
>
>> Not so. A lot of machines use the NiCd as the smoothing component. HP
>> certainly did in just about all of their more recent NiCd calculators (the
>> ones that use the 8V 50mA AC charger).
>
>Interesting. I haven't found where the battery gets in, but the input
>stage is something like:
>
> Diode
>Ring --+--/\/\/-|>|-+-----+
> | 56R | \
> | |C / 82R
> | |/ \
> +-/\/\/-+--| NPN /
> | |\ |
> _ |E |
>Tip--+ Zener A +-----+--- +5V? to rest of machine (??)
> | |
> GND GND
>
>I would guess the battery could well do any smoothing downstream of the
>regulator, but I'd still like to see some upstream of it!
>
>If the machine draws 60mA, minimum voltage at input is around 9V,
>maximum around 13V, so I suppose I could try 10V and see what happens...
>
>> Some, like the Epson HX20 even used the fact that the voltage across the
>> NiCd would go above 5V to limit the supply voltage to the chips. The
> ^^^^^
>I take it you mean wouldn't
>
>> If you have an adjustable PSU, apply about 5V, and then crank it up
>> towards 9V (I'd guess that's what it takes), monitor the 5V line and stop
>> if it rises above (say) 5.5V. See what current flows - it should be
>> arround 50mA.
>
>Worth a try.
>
>Philip.
>
>
>
Received on Mon Aug 18 1997 - 20:26:16 BST