[time-nuts] OT - Tek 7L18 ROM

Adrian rfnuts at arcor.de
Mon Nov 9 16:52:02 UTC 2009


Didier,

my 7L18 has been working fine in a 7603.
As by the catalog, it is compatible with any of the 7000 mainframes.
And, in the '82 catalog, the 7603 is suggested.

Btw. both MC schematics show a single +5V supply.
The believed to be early schematic shows 6 ea. 512 x 8 ROM's, while the 
more recent one that matches my 7L18 has two 2048 x 8 ROM's.

Mine appears to be from 1978. It's not listed in the 1977 catalog, but I 
have a product folder from 1977 introducing the new 7L18 :)
There is also a 1977 plug-in catalog with a note saying that it is 
currently available in the US and Canada, and that it will be available 
in other areas of the world in the first quarter of 1978.

Many thanks for all off the help. I hope to find a ROM image at a time.

Adrian


Didier Juges schrieb:
> My 7L18 only works in my 7704, and not in any of the two 3 slots mainframes 7603 I had at one time... Maybe the 7603 were defective (they worked with regular plugins at the time, but both developed ps problems soon thereafter), but the 7L18 works fine in the 7704, even with another vertical amplifier plugged in the empty slot.
>
> I had a picture of it on my web site, but it seems like it did not survive the last cleaning...
>
> Didier
>
> ------------------------ Sent from my BlackBerry Wireless thingy while I do other things... 
>
> -----Original Message-----
> From: Chuck Harris <cfharris at erols.com>
> Date: Mon, 09 Nov 2009 08:12:54 
> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
> Subject: Re: [time-nuts] OT - Tek 7L18 ROM
>
> Hi Dave,
>
> That is an issue that needs to be re-emphasized.  You can't read
> the EPROMS in a 7L18 without using multiple rail supplies.  +5V
> alone won't do it.
>
> Also, the 7L18 draws too much power for any of the 4 slot scopes.
> In spite of what the manual says, It is designed to operate in one
> frame only, the 7603.
>
> The biggest problem I found with mine was the tantalum electrolytic
> caps on the mother board kept failing.  Also there are a pair of
> shottky RF diodes being used as +/- 15V power supply isolation diodes on
> the YIG oscillator that fail, killing the phase lock capabilities.
> They need to be replaced with some real diodes ;-)
>
> -Chuck Harris
>
> Dave Baxter wrote:
>   
>> If no one else has said this.
>>
>> Check the mainframe power supplies.  The 7L18 is a thirsty beast.
>>
>> If anyone can back up the rom images, well done.  It's one of the
>> "classic" machines internally driven by the "Original" microprocessor,
>> the Intel 4004!  The Rom's will be of a similar vintage, multi rail
>> supplies etc I suspect.
>>
>> (I've only ever seen one other instrument that used a i4004 CPU, a
>> Finnegan GC oven!)
>>     
>
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