Denial

I miss two thinks on the FE3. - a clock like Mikes IRQ clock - some old fashion screen saver Do you mean these to be available while in the FE3 menus (rather than the BASIC wedge)? For the clock I'll have a think if that would fit on a subset of menus but screen space is tight so that wouldn't real...

I'm new to assembly language, and I would like to learn it for the VIC-20. There's a range of books that could be of help, which one(s) that will work for you depends on your background, how much knowledge you already have of the hardware, etc. https://commodore.bombjack.org/generic/generic-books-p...

This initial test is to check if any key in the matrix is down. Remember this function is called from the interrupt handler, it's trying to avoid burning CPU cycles when there's no keyboard input. Setting the column to all zeros mean the read of the row will be the union of all keys that are down. Y...

Here's the matrix keymatrix.png So 'M' is column 4 (b4), row 'E' (b4). The KERNEL routine loops over each column setting each bit in turn to be 0 and then reading the row. Pressing a key causes the row/column combination to shorted. The 6522 pulls inputs high when unconnected so this results in the ...

One can only think that indirect JMP in the SE code is a brainf*rt ... it really should have been JMP $A2C2 instead: Thanks for the confirmation. The way I work on these disassemblies is I note oddities when I notice them and then come back when I understand the code better. On a related note, I ha...

Oh no. This very bad. Flappy killed my floppy :( In Vice I had my working disk attached. Then I loaded Flappy and played it. Now I turn on Vice and the contents of my working disk is the one of Flappy bird. I was working on my text adventure. Lucky my I printed a listing (file vice.out) and lucky m...

Don't suppose you could tell me where on the PCB L3 is could you? I can not find it to save my life. Found L1, L2, and L4 I only have one CR VIC, looking at the PCB I can't see an L3 either. Here's a shot near the power switch vic20-cr-switch.jpg Tracing the circuit I make out the pins as the follo...

[Getting better voltages from socket, but I dont know how to "hotwire" the switch to have it always on, for testing purposes, until I can get another switch. So there is no switch on the board. Any ideas, Thanks in Advance. We can ignore the 9V AC side for now, it's not required for the m...

chysn wrote: ↑Sun Dec 31, 2023 11:08 am Anything else that just shouldn't be permitted?

Definately commas, and probably colons.

You might find the disassembly of the Super Expander useful to learn about this subject https://eden.mose.org.uk/gitweb/?p=rom-reverse.git;a=blob;f=src/vic-1211a-superexp.asm;hb=HEAD That uses a two step process when executing commands, first it handles arguments and then has another dispatcher that...

diagnostics I get this: register.... ok vendor/dev.... 144/144 rom/xmode....error#1 ram-mode1....ok blk-protect....ok blk-disable....ok ram-mode2....ok fe3-512kb detected OK, I think this shows that the CPLD and RAM parts of the hardware are OK. The vendor/device are still bogus and the ROM mode te...

I had been running a previous version of this firmware (Ultimate), and turned on my Vic-20 today and I get no menu etc, just a BASIC prompt. That doesn't sound good. I would think that would indicate the flash is either corrupt or not working at all. I want to upgrade to 1.7 so I have to use the fl...

KingtutUK wrote: ↑Sat Dec 23, 2023 5:41 am Can you tell me where "L5" is, as I can't locate it on the diagram or the board?

It's actually L3, the writing is not too clear
Have you checked P7 for wear? I had a board with intermittent power problems, replacing the socket fixed them.

According to the schematic L4 looks to be an inductor on the supply to the cassette motor http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/vic20/251027r2.gif I don't think it's involved in the +5V supply (but L5 is). If there's a voltage drop between the PSU and the motherboard I would fi...

If this caused the bits of the first byte to be shifted one to the left (like what an ASL would do for example) it would result in the byte value being multiplied by two. Check the contents of RSSTAT ($0297) after receiving the first character, I bet you have $02 indicating a framing error. You sho...