Commander X16 Hardware - March 2021 Update

BruceMcF · Post by **BruceMcF** » Tue Mar 23, 2021 11:16 pm

7 hours ago, SlithyMatt said:

Anybody who needs more than 128 bytes of RAM is just greedy. It was good enough for the Atari 2600!

Yes, it's outrageous that an ATtiny84 is being used when the much more frugal ATtiny24 has a whole 0.125KB of RAM AND EPROM, and KILOBYTES on chip flash storage. (I almost said "multiple kilobytes", but realized that once you hit "kilobytes", it isn't the one that has multiples of that.)

TomXP411 · Post by **TomXP411** » Tue Mar 23, 2021 11:20 pm

7 hours ago, SlithyMatt said:

Anybody who needs more than 128 bytes of RAM is just greedy. It was good enough for the Atari 2600!

Also the KENBAK-1, a huge commercial success.

rje · Post by **rje** » Wed May 12, 2021 6:06 am

So I watched his video again, and it looks like this:

He has the 65C22 connected on the I2C bus, since he did mention that the best way to set the system clock is to bit-bang through the 6522. But, the I2C header is also on this I2C bus. Therefore, it seems like an I2C storage device could load onto the system — perhaps main RAM, But also perhaps access the SD card?

BruceMcF · Post by **BruceMcF** » Thu May 13, 2021 10:24 am

On 5/12/2021 at 2:06 PM, rje said:

So I watched his video again, and it looks like this:

He has the 65C22 connected on the I2C bus, since he did mention that the best way to set the system clock is to bit-bang through the 6522. But, the I2C header is also on this I2C bus. Therefore, it seems like an I2C storage device could load onto the system — perhaps main RAM, But also perhaps access the SD card?

I am not following the question ... any I2C storage device with power and the correct connection could be accessed FROM the system ... if the 6502 is bit-banging as the I2C master, the 6502 would have to get the bits from the I2C storage device and then store them on the SD card. But, yeah, it seems like the CPU would be able to copy information from an I2C storage device into any other storage it can reach.

I see that the FTDI still offered their 5v tolerant USB to I2C slave bridge chip, so while slower than User port parallel, I2C to USB would be a PC file transfer option.

rje · Post by **rje** » Thu May 13, 2021 6:21 pm

^ Yeah, I get it. I was more wondering about Kevin's I2C daughterboard.