Service bureaus (Was: Tek 4051 firmware listing

Jules Richardson jules.richardson99 at
Thu Dec 16 16:33:36 CST 2010

Tony Duell wrote:
>> I'm pretty sure the Micropad OCR gadget (circa 1980) that I once had required 
>> slashing of the letter 'o', with the unslashed version interpreted as a zero.
>> (and to comment on another thread, I think the 286 Compaq luggable that I had 
>> for a while had a dot in the middle of the zero rather than a slash - I'm not 
>> sure if that was a standard feature or something oddball about my machine)
> FWIW, I've just pulled a book off my bookshelf. 'Assembler Language 
> Programmign, The IBM System/360 and 370', 2nd edition 1975.
> It says  : 
> 'Note that the letter O (Oh) is written as 0 to distinguish it clearly 
> from the digit O (sero). We follow this convention in the description of 
> any statement or card that is fed to the computer'

Also found out that my Micropad was related to the Quest Automation Datapad, 
and the Datapad was used against DG Nova machines - was there any history of 
DG hardware using slashed "ohs" and unslashed zeros?



More information about the cctalk mailing list