Nostalgia Rules! Ok

[bartleph]

Hello and thank you for letting me join your forum. Wow...what a wealth of knowledge, and memories stored among these messages.. I like many intrepid explorers before me embarked on the beginnings of an interest( and career ) by purchasing a UK101 kit as promoted in Practical Electronics. I built it and had it up and running in about 5 - 6 hours. I learnt a lot about the 6502 and it's peripheral devices on that UK101. As with most things it retired to the attic and was thrown out at a later date as having no value ( How naïve!!) I missed it and set about building a complete new system on stripboard..I even persuaded two colleagues to do the same and we then had a little club of homemade UK101s. Along came memory expansions and a Floppy Disk system. OS65Dv3.1. We even coded a BASIC 5 extension, new DOS,EPROM Burner and printer interface. Eventually we lost touch and those stripboards became unusable and were dumped. I am a 6502 junkie and couldn't just let it go..nostalgia is much too much of a drug, so I built FPGA versions from Grant Searle's amazing web pages, but really hankered for my own 6502 Dev Board. PBW65C02v1 rapidly morphed into PBW65C02v4 and now sports 32KRAM 32KROM 19200 bps serial interface with a modified Cegmon Monitor. I found my original 3M Floppy Disk with OS65Dv3.1 on it and the temptation was too great. I designed and built a Floppy Disk Interface based on the Elektor Junior/OSI schematic, and lo and behold after relocating the serial ACIA from F000 to 8000(where mine sits) and setting IO to serial, and Ramtop from BF to 7F I have a DOS3.1 up and running. My >30 years old disk still remembers its code!!. I now have a Gotek running as drive 0 and the 5.25 drive as drive 1 so I can hopefully read/copy some of my old program disks.
I am trying to modify the OS65D3.3 image so I can run that but have hit a snag. Initial boot hangs and entering via monitor and $2A51 gives A* so that appears ok. BA loads Basic (It shows 50817 bytes free !! and trying to load a program gives OM Errors) EM works fine, but AS hangs. Does anyone have an explanation of the boot process up to the point of running BEXEC*? i.e. Track 00,1 loads to 2200, track 01,1 load to 2A00 etc etc.
I still cannot believe my Master Floppy has all its software intact after all this time. I did mark it as a 'Master Disk' and write protected it but I thought any magnetic information would have decayed by now... Thanks again and I hope to contribute regularly to this excellent forum. KRs Paul

[dave]

Hi Paul! Welcome to the forum. We look forward

It has been a while since I've gone through the boot process, but the OS65D disassembly manual is a useful resource:

https://osiweb.org/manuals/OS65D_Dissasembly_Manual.pdf

Hopefully someone else will chime in.

If your system has RAM from 0000-7FFF, I imagine a memory test would continue to $8000, and if you have your controller there, It may be possible that any memory tests could interfere with your controller hardware. If you disable a segment just below $8000, does that make any difference?

Cheers,

Dave

[bartleph]

Thanks Dave. The disassembly is proving most useful. I have DOS working almost!! after changing the ACIA address to match mine, defaulting the IO to device 01, and as you suggested, setting memtop to $7F instead of $BF. I can boot OS65D and Basic,Asm and EM load and run. Bexec* runs on boot and I can unlock. Track zero read/write from TK 13,1 to $0200 works fine BUT I cannot DISK!"PU from Basic or SA XX,Y =ZZZZ/N from DOS. The fact that track zero read write works tells me the drive is working fine but I have yet to figure out why I can't save any other tracks either from DOS or BA/ASM.
Any help hints or suggestions will be gratefully received.

[bartleph]

I did say I would post more info so here goes. I have copied the Elektor Junior Floppy disk interface and had some PCBs made up. After assembly and connecting up to my W65C02 board I was able to read in Trk 0 & 1 from my ancient 3M 5.25 Floppy Labelled "OS65DV 3.0 24x24 Display, 25ms step speed". As my system is a serial without VDU, I modified the output routines to print out via my ACIA @ $8000. All worked fine apart from unable to write to disk. Saving a modified BEXEC* resulted in ERR#9 and a track 14 full of zeros!! On further examination I tested the output Data clock and found it was 250kHz NOT 125kHz!! That would explain why written data was faulty. It turned out that one of my IC socket pins was shorting with an adjacent 'via' on the pcb, effectively messing up my counter used to derive the 125kHz clock...Once corrected all appears to work fine. I know need to modify OS65DV3.3 to get that up and running on my system. I will also say I have a couple of Goteks with FlashFloppy 3.29 installed and they work great individually, and when used alongside my TEAC FD54A. Just need to get them to work together...but that will have to be another story. Can I say thank you to this community as a whole because I have gleaned so much from your postings. Information is key and I value this resource.