Re: Boarding pass: a work in progress.

[Roger Johnstone <roger@roger.geek.nz.removethisbit>]

In <MaSdnZZpefhvTizYnZ2dnUVZ_riknZ2d@comcast.com> Michael J. Mahon wrote:
> Linards Ticmanis wrote:
>> BLuRry wrote:
>> 
>>>Like the CPU, the video core is a timer-based object that works at a
>>>pre-determined interval (1.023mhz).
>> 
>> 
>> Why 1.023? The real Apple runs at 1.020484-ish
> 
> Thank you, Linards!  The erroneous "urban mythic" clock speed of
> 1.023MHz or 1.024MHz for the Apple II has always bothered me.
> 
> But it's clearly a case of cognitive dissonance--2^10-1 or 2^10
> are common numbers.

Apple II Reference Manual (1981): "1,023,000 machine cycles per second"
That's presumably the result of someone rounding it to 1.023 MHz, then 
writing it in hertz.

Apple IIe Technical Reference Manual (1986):
In various places it says 1.02 MHz, 1.023 MHz, and 1.02273 MHz. The 
first two are obviously rounded versions of the last number. 1.02273 is 
the main crystal frequency of 14.31818 MHz divided by 14, so the Apple 
II does run at 1.023 MHz rounded to three decimal places. Unless I've 
missied something?

-- 
* Roger Johnstone, Invercargill, New Zealand -> http://roger.geek.nz
* PS/2 Mouse Adapter for vintage Apple II or Mac
* SCART RGB video cable for Apple IIGS