After getting timer and W65C21 interrupts working, I built a small test setup ...

The image 1 below shows the output of pin 10 (PB0) of the W65C21 and is toggled via Timer7 interrupt routine.

pic1.jpg

The image 2 below shows the output of pin 38 (IRQAB) which signals an interrupt for negative ...

Thank you very much for taking the time and giving me this advise.

You have collected really interesting stuff there and I am sure it will be a pleasure to read through.

A lot of info mixed with practical tips ... I love it.

If it's like the 65c22's timers (and other 65c22 portions), you might ...

Shame on me!!!

:oops: :oops: :oops:

I think I must have been blinded or otherwise mentally absent when I was reading the timer section of the datasheet. May have been messing around with the MSP430 what caused the confusion on how the timer was supposed to work.

After programming some ...

Hi folks, and thanks all who stopping by!

After a couple of days of "vacation" on a MSP430 I am back on this project now. I took some time off because I couldn't get the TIMER7 to work with interrupt enabled. Even a simple handler with only a RTI did not work, all I got was a locked up CPU.

While ...

Hi folks!

today I am very happy to be able to announce that the PIA 65C21 now works on the breadboard. Both ports, configured as output, are lighting up some LEDs implementing a simple counter.

PIA 65C21 working.JPG

As suggested in this thread, I tried to simplify the address decode logic to a ...

Hi!

time for another project update from the last weekend.

Initially everything went well. I managed to build the logic circuit like presented in the previous post. This time using the components I had at hand, which later could be replaced by the suggested faster components.

To test the circuit ...

Mmmh ... but who takes care that the CS4B External ROM and the CS0B PIA won't interfere, since both overlap in terms of address range?

If you dare to solder a tiny wire to the outer pin of resistor network R6 left to P17 of J4 you have P70=CS0B which you could use as chip select for your PIA ...

Hi!

Thank you very much for your help!

I had no idea about such huge timing differences. I assume we are talking about the propagation time. As of the data sheet, the CD4081 is about 10x slower than the 74HC21 you suggested.

The image below shows the memory map from the WDC data sheet. As of my ...

Isn't that what happens right after "Enhanced BASIC 2.22" ?

Could also be that the $00 isn't catched and output continues fetching characters beyond the text.

Switching terminal output mode to HEX could leverage the mystery what these characters are ore come from.

Just a thought.

LAB_MSZM
!raw ...

Hi,

a quick look into the source code around line 7800 shows that the line endings are not consistent. Several $0A without preceding $0D. Also the "garbage" in the terminal seems pretty constant to be anything random.

LAB_MSZM
!raw $0D,$0A,"Memory size ",$00

LAB_SMSG
!raw " Bytes free",$0D,$0A ...

Hi!

this weekend I am planning to add one of my W65C21S Peripheral Interface Adapter to my breadboard assembly.

I am not sure about the required logic for the three chips RAM, ROM (currently NVRAM) and the PIA to play nicely together.

I came up with the following idea, which would require 3 ...

Hi!

I am using ACME (https://sourceforge.net/projects/acme-crossass/) assembler and threw your sources at it. After some minor adjustments (see sources attached), it assembled a binary.

I did run the command without the Makefile.

acme -f plain -o b.bin min_mon.asm

As ACME does not produce HEX ...

Hi Andrew!

Great to hear you are planning to implement the assembly feature in the monitor. It would be a great way for beginners to try out the different opcodes to figure how to use them. This is what I am using this functionality for.

While playing around with the assembly and disassembly I ...

Hi again!

@BigEd thanks for stopping by ;-)

In one of the previous posts I mentioned that I was looking into developing some kind of interactive assembly tool running as user command under the monitor ...

Well, here is what it looks like ...


>u
USER>a

Interactive ASSEMBLY Tool ...

After destinating this gray and rainy sunday afternoon for digging into the protocols with a logic analyzer tool, the reason the display didn't work became obvious. It was a silly bug in a hex to binary conversion routine. With this fixed, the display started to work like a charm.

As mentioned in ...