Newest mos-6522 Questions - Retrocomputing Stack Exchange The 6522 VIA is an I O chip used in the Vic-20 I was under the impression that UART (Universal Asynchronous Receiver Transmitter) is the general term for such chips, so was surprised to see this:
Does the 6522 VIA swap the registers for ports A and B compared to the . . . Where the 6522 features 4 address (register select) lines for its 15 registers, the 6520 features only 2 (RS1 RS0), but has to operate 6 registers Thus the corresponding data (ORx IRx) and direction registers (DDRx) share the same address 00 for port A and 01 for port B
Why does the Vic-20 have two VIA chips? The Vic-20 uses the 6522 VIA for peripheral I O However, it has two of them I find this surprising, particularly considering minimizing cost was an important design goal Is there a reason why it
Newest mos-6526 Questions - Retrocomputing Stack Exchange Comprehensive test suites for MOS 6520 PIA 6522 VIA 6526 CIA Are there any automated test suites for MOS 6520, 6522 and 6526 chips? I am looking for test suites aimed at making sure datasheet-based independent reimplementations of the above chips (e g FPGAs or
Can the 6502 clock be changed on the fly? 1MHz peripherals are clocked by a 1MHz 50% duty cycle square wave (chosen to allow chips such as the 6522 to use their timing elements reliably) The BBC Microcomputer's cpu normally operates with a 2MHz clock, but with a slow-down circuit which has the effect of stretching the "clock high" period immediately following the detection of a valid