sup8pdct

The right is a very close to rev B 800 rom with a few changes in the cassette serial routines plus other small changes. The left appears to have Bit 3 set right through. Either the rom is stuffed or pin 13 on the rom wasn't contacting properly with what ever reader you used. James

Does this disk require the use of an Oscilloscope??? Set tracks have different alignment waveforms on them. James

Mine was also a little washed out. From memory, I had to replace the transistor array due mostly to cross talk between the transistors on the chip for audio. also from memory, I had to play around with the values on the the mother board or disconect the audio carrier inject circuit on the mother board due to feed back from that part of the circuit. Have included a circuit diagram from the relevent part and noticed that there is no 75 ohm resistor for the composite or the chroma. Maybe I fitted a 75 ohm resistor in place of L104 and L105. Has been many years since I done this and memory is very dim at this moment...... P.s. ignore the circle I drew on the schematic. Was for something but cannot remember....... James

No. there are at least 3 voltage regulators. a 7805, 7812 and a circuit that gets -5V from the AC input. All 3 are required by the ram chips the 800 uses. There is a diode pump along with 2 capactors to get the requided voltage for the 7812. a similar setup is used to get -5 volts The power led is powered by the -5V rail. When using the proper power supply unit, does the power led come on? If not, check to componants for the -5v supply. Here is a schematic of the 800 power supply board. james

No one has suggested to check the drive belt. just check it isn't loose and/or slipping. When a disk is inserted and the drive door closed, the head steps in then out again depending on what upgrade has been applied to the 1050. They all spin the disk so the density is checked and internal parameters set. James

If I am not mistaken, there are no start or stop bits. Looks like the joystick ports are the way to go. Easier to get the kernal and mod it a bit to work..... James

I have found a little bit on info here http://www.classic-games.com/commodore64/drives.html. Nothing about the serial however. Maybe time to pull apart the kernal to see what happens. James

I am interested to know how you transfer the files across. What are you going to do when you get a 180K image? Personally, if you can use a soldering iron and can follow a small schematic + instructions, it would be much easier to roll your own sio2pc interface. The hard bit is where to/what to sacrafice, to get it going, ie what cable to cut or where to put the interface. If you have an old clunker pc that has dos or win 98, the dos freeware version of ape is the way to go. I personally haven't looked at the windows version so cannot comment on it. James

I have heard that the C64 serial was 1200 baud to/from the drive which is why speed ups were so popular. Hell, the atari can bitbang that out the joystick ports during the VBI (well, almost) James

I personally think it would be neater externally to have a PBI like the XL line. However, I think you will need to change the MMU over to a XL/XE one. The GS has an extra line used on PIA for the game which happens to take the MPD line from the PBI, So tracks need to be cut etc James

I just a real quick look at the mux rom. the 800 v ersion would also loose the config menu. I can re do it If you want, but won't be able to look at it till after easter. Then you will need to get it going in the 800. James Yeah, true.... I'd still like to find out how to use a 1200xl with them though. They are my main atari. Puff said it could be done. Something about needing a second rom.

unfortunatily, no. i lost them years ago. i did have to mod them a bit. ie get the nmi reset working. I did it just to see if it could be done. leaving the cart door open all the time would be a bit of a pain. I Used a local rom upgrade board that had both a 4k and 8k rom on it for $Cxxx and $E000-$FFFF reagons. The orignal maths rom was left in. James

Will the ones you do have space for the 2nd buffer chip for the address and control lines? Mine has space for them but not inserted. Mine also has some fine wire joining several pads on the underside in the power supply section. James

The master is fully tied up with a program running to monintor the multiplexer and do sector level access to the shared devices. Each slave has a modifyed rom that has it's disk and printer SIO routines redirected to use the multiplexer instead of the serial/pbi bus. Rs232 is left alone. Each slave is limited as to what dos it can use. The master can run any dos. I once modifyed the slave rom to run on an 800, then had the 800 on the chain. I told Bob Puff I had done this, he was amazed. James Does it tie up the master or can it still run programs as a workstation too?

It also depends a lot on your screen. some support artifacting much better then others. some don't at all. Yet others will show different colours. James

at ebb9 and ebc0. Hold on, I see what is happening. I missed a conditional .IF way back in the variable define area. It means I have missed 2 bytes that should have been changed. All fixed James I didn't mean "people" should do that. I've been reading here that PAL rev B was very rare, considered as possibly lost or even never released. So what I meant is that it should be (almost) trivial to re-create it from the listing, even if it was never found. Of course that confirming with an actual ROM chip is very good. What error did you find? I just compared the PAL rev B you posted with the "known" NTSC rev B. I found 11 bytes to be different. Didn't double check, but these bytes seem to be exactly the ones marked in the source. ATARIOSBpal.zip

Not baud rate tables but baud adjustment values and time out values due to the different vblank rates. James

He doesn't have a Pal os B. James

How many people out there would like to type in or verify every byte in the OS as being true and correct? I also have the source listing and have found at least 1 byte that is in error compared to the source. The routine is the same in rev A and compairing pal V ntsc shows the difference. Also, there is a project that Warerat is doing that I have put up my hand for one. I personally would like a true and correct rev B PAL version of the os to go with it. James Hi James, Isn't it trivial to "produce" or to confirm/verify rev. B PAL OS? We have the official source listing. The difference with the NTSC version is noted in the listing with conditional assembly, and should be something like a dozen bytes. Or I am missing something ?

Maybe you need to remove the first 6 bytes that is a dos overhead for them to work. James

That one is actually a modifyed rev B ntsc. $E6E7 has 3 NOP's which shouldn't be there. The timings in the sio routines are set to NTSC. Special cart routines have been bypassed. Key repeat timings etc. All the mods point to a translator disk version. Sorry to say, but that file isn't named correctly. I have been finding that a lot with the rev B. very hard to get a true and correct version. James

I was slightly annoyed after getting my 3rd 800, all had rev A and GTIA. I was under the impression that we never got CTIA. Yet to see one with that chip. James

Where? James

Would be interested to see it. It may or maynot be completly orignal. James

Yes. checkout http://www.atariage.com/forums/index.php?s...00#entry1712834 That is rev A PAL, just like the 400 and 2 800's I have here, right down to the same chip part numbers. Rev B didn't come out till early 82. Am sure atari had Computers here before then. James