More often than not when I visit this site, I am blocked by "403 Access Denied" errors. Sometimes I can view the site through my ADSL connection, but not via GPRS on my phone. Sometimes the other way around. The next day the problem disappears. Why this happens?

Yesterday I was finally able to resurrect my 720 I pulled a strange kernal from it, labeled "324866-03A Kernal DIN". Comparing it to a normal kernal, it shows that the video section at $E000-$EE00 is vastly different. But the kernal boots in VICE normally. I was wondering, what kind of kernal is it?

There was also "324867-02 Character DIN" in the character ROM, but the EPROM did not survive and I wasn't able to read its contents. Since the character ROM was different, maybe it means it was some localised version?

I am trying to find out the easiest way to discover whether a given IEEE device (let's say: a disk drive) exists, from an assembler code.

I have been thinking that simply sending a TALK or LISTEN command to a non-existent device would result in some value of "Status" variable that would tell me that the device is not present. But it's not the case. I need to actually read something from a device, and only then the ACPTR command sets the "Timeout" bit in the status variable if the device is not there to send anything.

So the correct way would be to make a device actually send something to the computer. But I am not that proficient in the low-level details of the IEEE interface, so I don't know how to prepare the device so that it sends me something. I guess I need to call LISTEN and SECOND, tell the device that I need something from it, then TALK and TKSA... but with what parameters? I have no clue. I would appreciate any help.

I have recently acquired a 720 which does not work. This does not trouble me much, as I am going to open it up soon and examine with an oscilloscope, and perhaps I will be able to get it back alive like I did with the 610.

But it does not have a keyboard, and I have no idea where I could get one (besides cannibalizing my 610 and changing the plug). Do you perhaps know a source where such keyboard could be obtained?

I'm back Due to some business circumstances, I wasn't able to focus on the 610 programming in the past weeks. But now I have some free time again, and I'm back at work on the IEC routines.

Here's the first useful program I wrote - a utility that downloads files from PC via XModem protocol. I will be using it to upload compiled software from my PC to the 610, to save on burning EPROMs

100 print "Enter filename:" : input f$                                       
110 open 1,8,3,f$+",s,w"
200 open 2,2,3,chr$(26)+chr$(1)
210 print#2, chr$(21);
220 b = 1
300 gosub 500
310 if asc(c$) <> 1 goto 600
320 gosub 500
330 gosub 500
340 for i = 1 to 128
350 gosub 500
360 print#1, c$;
370 next
380 gosub 500
390 print "Received block "; b
400 b = b + 1
410 print#2, chr$(6);
420 goto 300
500 get#2, c$ : if st = 16 goto 500
502 if c$ = "" then c$ = chr$(0)
510 return
600 print#2, chr$(6);
610 close 1 : close 2

On PC, fire up HyperTerminal, select the COM port, and leave default settings (2400, 8N1). Select Transfer -> Upload file, choose XModem and browse to the file. Then click Upload.

On Commodore: run the program, and enter the name of the file to be saved (it must not exist). The download process now will start.

Of course, you will need an appropriate nullmodem cable, with DB9 female at one end, and DB25 male at the other. I bought such cable on Ebay for 5GBP.

Enjoy!

I just upgraded to 256 kB. Two hours of soldering The cold startup time is now 8 seconds. Not really bad, but annoying.

Since we are creating a IEC cartridge, I thought of putting it at $2000 (so it would be the first cartridge to run) and include our own initialization routine. It would perform all normal initializations, but with only a rudimentary memory check to speed up the startup. Then it would continue searching for cartridges starting at $4000.

You can notice that in the text mode, there is always a 1-pixel space between characters. That causes unpleasant rendering of tables and other graphics characters. In graphics mode, the 9th column of each character is repeated after the 8th, so this does not occur.

To fix this, simply cut the pin #1 of chip U55 (on high profile machines, this is pin #13 of chip U83). This will make the 9th column also be repeated after the 8th in text mode.

Unfortunately, this makes the "m" and "w" characters to be displayed a little bit weirdly because they have some pixels in 8th column. This needs to be worked upon

Is there any reference of the built-in monitor commands? I was not able to find any on the Web. And it's been 15 years since I last used a 6502 monitor...

I would like to be able to load/save a specified memory range to disk, for example.

If you have any spare, I'd gladly buy it - seems rather expensive to buy a whole C128 to rip just one chip off it...

Pretty much as the thread title says... I need something for my 8250LP, and these QD disks are impossible to find... if you have any to spare, I'd be grateful. I was overbid on today's Ebay auction for 4040

I just joined the board so I thought I would say hello I come from Poland, and I have been a huge fan of Commodore in my youth. Now I have reached a point in life that I have finally some limited free time so I decided to return to my passion.

So I purchased a Commodore 610. Currently I am gathering peripherals (disk drive etc.), and getting to know the schematics as well as the kernal.

Apart from obvious things (like extending RAM to 256k), I plan to plant the 8563 VDC chip into the computer and do other cool stuff with it