Re: Help with SX64 User Port?

From: smf <*smf_at_null.net*> Date: Wed, 28 Jun 2017 14:00:11 +0100 Message-ID: <0811a926-80ec-dbb4-4ade-a56edf97272a@null.net> · smf_at_null.net

On 28/06/2017 01:44, Mia Magnusson wrote:

> The 1541 is a rebranded 1540 with some slight changes in the ROM code.
> The 1540 were made for VIC-20 and shares the same 6522 VIA:s that
> VIC-20 uses.

The 1540 appears to have been based on the 2031 IEEE drive for the PET.

I assume that commodore didn't want to pay to redesign the PET drives, 
because the 6526 was out in 1981 (or at least the datasheet was). 
Although it's possible the 6522 was cheaper to make or had a higher yield.

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