OSI 505 Rev B BUILD

[musovern]

After my success of the 502 board and now my 540b board It was time to start the 505 Rev B board. I got a few boards make from the gerbers files available on here thank you Dave. And have now finished off my build I'm hope to configure for a serial only system with a RAM board installed and attached a floppy disk at some point, have made the necessary cuts and added pullup resistors for the ROM Mapping system so I can easily wire wrap when it come to configuring for serial system ROM. Plus added the 9600 BAUD change.

Have attached photo



At present I have the SYNMON1 ROM installed and have the default configuration for the H/D/M boot and the 65V monitor with Keyboard. All seems to be working well apart the serial output. I can upload through the serial port but don't have output. I have checked the serial cable and the looked for bad solder connections and double checked the transistor and resistors for RS232 output etc but nothing found yet. Have put a logic probe on pin 6 of the 6850 and it just stays high all the time, it's like the (WRITE Signal) on the R/W pin of the 6850 is not being activated if that makes any sense. Would anyone have any suggestions on what to try or look for.? I did try Marks serial echo program but will not transmit either as you can see in the photo I uploaded the OSI Disk Tools over serial connection and it loaded fine.?




Cheers

Vernon

[Mark]

Does DiskTest menu & I/O operate correctly where expected (changing options etc.)?

So the OSI monitor ROM initializes 6850 with $B1 or %10110001 which is 8N2, /16, rx & tx IRQ enabled.
After loading, the DiskTest program initializes ACIA with $15 or %00010101 which is 8N1, /16, rx & tx IRQ disabled
The serial echo program does not change ACIA settings.

Do you have IRQ line connected on 6850? Perhaps OSI is jumping to IRQ vector & hanging without a handler installed? Try reseating 6850 without pin 7 installed?

Try loading serial echo, but then reset OSI, enter monitor & type

Code: Select all

.FC00/03 15 .0300G 

echo program should work (assuming it starts at $0300).

-Mark

[Mark]

(I forgot that after loading, DiskTest allows you to use OSI video & keyboard, bypassing serial I/O so my question about proper operation really only applies to serial console mode.)

[edit]
Also what state is CTS? If you open the monitor & enter

Code: Select all

.FC00/0315.FC00

what is the value you see? (I see 02)

[musovern]

Hi Mark,
Thanks for your help and suggestions.
I have checked that pin 7 of the 6850 is not connected to anything also lifted pin 7 and reseated the chip just to be sure then loaded the serial echo at 9600 8N1 did a reset then did .FC00/03 15 .0300G but nothing still seems the same.

The DiskTest menu does operate fine over the keyboard and video setup changing options etc can also exit out and restart typing .300G and the video menu comes up again. (I have not got up to adding a disk drive yet so cannot test drive options next on the list). One thing I did notice is that once the DiskTest menu come up on the video screen if I hit any key on the serial terminal it will freeze.
I didn't really unstandstand what was going on until I pulled out the 505 board and put in the 502 and tried the same test.
When uploading the DiskTest program on the 502 board the message "Hit any key to select console device" when I hit a key on my serial terminal it takes over and works from serial console as expected. So that will be why the 505 board seemed to freeze once the program loaded the serial in part works but not the output.

At least I'm starting to understand a little now what is going on.

oops didn't see that last bit.
for
CTS?
.FC00 /0315.FC00 I get 08

cheers
Vernon

[musovern]

Hi Mark,

Update It's now working serial and all Ya

you were onto it with the CTS pin 24 was stuck high so was getting NO serial output. A bad MC1489 about the only chip I never tested with the Retro Chip Tester pro. I should have thought of that myself. Never mind, thanks for your insight and help again. Ya another board working.

cheers
Vernon