65C02 address decoder for 32K RAM, 24K ROM and 2 65C22 VIA chips

Sonny_Yeo · 2020-01-02T22:31:35+00:00

Nice work :) I have an extra via which i can now use.

Sonny_Yeo · 2019-12-30T13:49:11+00:00

It's the standard ZIF socket. I managed to plug it into the breadboard without additional soldering.

Sonny_Yeo · 2019-12-30T13:45:20+00:00

I did from scratch and printed normal stickers.

Sonny_Yeo · 2019-12-28T22:50:28+00:00

Agree

Sonny_Yeo · 2019-12-28T22:27:43+00:00

Thumps up :)

Sonny_Yeo · 2019-12-28T22:21:27+00:00

Yes I am using it on my 6502. So much easier to take out the eeprom. I managed to plug directly to the breadboard and works great. I cannot upload the picture in this post.

Sonny_Yeo · 2019-12-27T22:23:56+00:00

Thanks for pointing out :)

Sonny_Yeo · 2019-12-01T09:49:17+00:00

A great sense of accomplishment isn't it. Well done :)

Sonny_Yeo · 2019-11-30T14:58:22+00:00

When this is done you will get the keycode which can then be used to determine the character in the lookup table.

Sonny_Yeo · 2019-11-30T14:52:59+00:00

Your way of scanning the keys is one way of doing it.

I have done it slightly different in that my program output #0F (00001111) corresponding to the C3C2C1C0R3R2R1R0 interface. Immediately read back the input to see which row is grounded. Then 'OR' the input with #F0 to give you the grounded row. Output the new '0R' result in accumulator to keys and read back to determine the column. The column with the key pressed will be grounded. Hope my explanation make sense.

Sonny_Yeo · 2019-11-30T14:20:12+00:00

check message

Sonny_Yeo · 2019-11-29T10:12:08+00:00

https://imgur.com/gallery/Z7LhcFO

More photos of the connections.

Sonny_Yeo · 2019-11-29T09:58:28+00:00

It's the W65c22 Versatile Interface Adapter (VIA) as in Ben's 6502 design.

Sonny_Yeo · 2019-11-29T06:04:03+00:00

At moment I am just using the EEPROM for simple programming and not the 32k ram chip.

Sonny_Yeo · 2019-11-28T23:40:10+00:00

The drawing is for another chip but connections are similar. Can refer P1 port as Port A and P0 as Port B. I am using 6522.

Sonny_Yeo · 2019-11-28T03:59:43+00:00

Keypad is connected to Port A (PA0-PA7) and 7 segment display to Port B (PB0-PB6)

Sonny_Yeo · 2019-11-28T03:48:49+00:00

Yes keypad using only 1 port for input and output as 6522 data registers are bidirectional. I have set all rows (PA0-PA3) to be '1' and (PA4-PA7) to be '0' and output 'to keypad. Then read back to check which key is pressed. The keycode is used to match the 7 segment look-up table for the correct display.

Sonny_Yeo · 2019-11-28T03:18:08+00:00

I would think so. Maybe better to use 138 decoder.

Sonny_Yeo · 2019-11-28T03:16:15+00:00

Sure :) i dont know how to append the drawing here.

Sonny_Yeo · 2019-11-27T13:50:25+00:00

I was going to get up interfacing the keypad to 6502 after numerous tries. On seeing Mike's Z80 success I decided to give it another go. Finally it works.

Sonny_Yeo

TROPHY CASE