6522 versatile interface adapters

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BadProgram
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6522 versatile interface adapters

Post by BadProgram » Thu Nov 14, 2019 4:06 pm

Hi i was wondering what the exact address of the user VIA is ?

In the advanced user guide it says :
Image

is the User VIA &7F and &80 ?, there were no code examples i could find in the guide.

i was seeking to use the "T1" reg timer but could not get started without an address.

More from the user guide (for reference)

Image

Image

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1024MAK
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Re: 6522 versatile interface adapters

Post by 1024MAK » Thu Nov 14, 2019 4:21 pm

All the internal I/O devices including the two VIAs are memory mapped in an area called SHEILA. This runs from 0xFE00 to 0xFEFF. But not all addresses are used and not all are fully decoded.

The text of the advanced user guide only gives the last two hex digits of the address. The first two hex digits are FE.

See this detailed list of devices in this area.

Mark

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BadProgram
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Re: 6522 versatile interface adapters

Post by BadProgram » Thu Nov 14, 2019 4:39 pm

Thank you very much 1024 Mark this is exactly what i needed.

(for anyone looking in the future)

FE60-7F User VIA
================
FE60 Output register B (User port) Input register B (User port)
FE61 Output register A (Printer port) Input register A (Printer port)
FE62 Data direction register B Data direction register B
FE63 Data direction register A Data direction register A
FE64 T1 low-order counter T1 low-order latches
FE65 T1 high-order counter T1 high-order counter
FE66 T1 low-order latches T1 low-order latches
FE67 T1 high-order latches -
FE68 T2 low-order latches T2 low-order counter
FE69 T2 high order counter T2 high order counter
FE6A Shift register Shift register
FE6B Auxilary control register Auxilary control register
FE6C Peripheral control register Peripheral control register
FE6D Interrupt flag register Interrupt flag register
FE6E Interrupt enable register Interrupt enable register
FE6F Output register A, no handshake Input register A, no handshake

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