My 610 board build.

[HOWARDHB]

...strange indeed!

I note that U6 & 7 are not N8T28 , however, MC6889P are "equivalent". Their DD (data direction) pins (J3 pin 3) should be tied at a little above 2.5V, (R9 220R and R74 390R )

Try removing the MC6889's ...

Also, check that J1 pins 1 and 2 (NMI and IRQ) are pulled properly " high" (by 4k7, R10) and R11)

Check if clock 02 (J1 pin 31) is oscillating...

[ronin47]

...strange indeed!

I note that U6 & 7 are not N8T28 , however, MC6889P are "equivalent". Their DD (data direction) pins (J3 pin 3) should be tied at a little above 2.5V, (R9 220R and R74 390R )

Try removing the MC6889's ...

Also, check that J1 pins 1 and 2 (NMI and IRQ) are pulled prooerly " high" (by 4k7, R10) and R11)

Check if clock 02 (J1 pin 31) is oscillating...

Are you referring to the 610? I don't have all the IC's so I haven't hooked it up with any power yet.

However if you're referring to the 600D then I have 8T28's IIRC. I'll have to go away and check this stuff, problem is I have a poorly Amiga 500 that is demanding my attention and workbench space as well!!!

EDIT:

Well just to confuse things, mine are labelled both MC6889P and MC8T28P...

Also, I would add that it makes no sense that a cable being plugged into the 600 would make it fail to boot. There is normally only an empty socket and the cable just extends it when it's not connected to the 610.

[HOWARDHB]

[quote.Also, I would add that it makes no sense that a cable being plugged into the 600 would make it fail to boot. There is normally only an empty socket and the cable just extends it when it's not connected to the 610. [/quote]

I agree, it's a mystery, for now...
Do check that DD is in fact slightly above 2.5V with no bus drivers in the 600's U6 and U7 sockets.

[ronin47]

[quote.Also, I would add that it makes no sense that a cable being plugged into the 600 would make it fail to boot. There is normally only an empty socket and the cable just extends it when it's not connected to the 610.

I agree, it's a mystery, for now...
Do check that DD is in fact slightly above 2.5V with no bus drivers in the 600's U6 and U7 sockets.
[/quote]

Thanks Howard will do.

[dave]

Also, I would add that it makes no sense that a cable being plugged into the 600 would make it fail to boot. There is normally only an empty socket and the cable just extends it when it's not connected to the 610.

A wire (or 40 of them) hanging off the main board with no connection at the other end acts as a stub and as an antenna. As a stub, a reflected waveform with a 1 MHz fundamental would have almost no effect for a 15 cm (~6") wire (or any wire less than 30 m, for that matter. As an antenna, though, the cable could be susceptible to RF interference up to 200 MHz, and depending on the capacitance of the line, this could get integrated sufficiently to interfere with normal operation. Even infrequent glitches can prevent a boot, especially with 40 lines.

What happens if you just place an uncrimped DIP socket connector in the socket, without the cable? If that's OK, then try a socket with a 12" cable. If that's OK, cut the cable down to the desire length. If that's OK, then place the other DIP socket connector on the free end.

I do know that if you attempt to connect an unpowered 610 board to the 600 board, your 600 will not boot. But that's not what is happening here, of course.

Nice build! Please keep sharing. . .

Dave

[ronin47]

Also, I would add that it makes no sense that a cable being plugged into the 600 would make it fail to boot. There is normally only an empty socket and the cable just extends it when it's not connected to the 610.

A wire (or 40 of them) hanging off the main board with no connection at the other end acts as a stub and as an antenna. As a stub, a reflected waveform with a 1 MHz fundamental would have almost no effect for a 15 cm (~6") wire (or any wire less than 30 m, for that matter. As an antenna, though, the cable could be susceptible to RF interference up to 200 MHz, and depending on the capacitance of the line, this could get integrated sufficiently to interfere with normal operation. Even infrequent glitches can prevent a boot, especially with 40 lines.

What happens if you just place an uncrimped DIP socket connector in the socket, without the cable? If that's OK, then try a socket with a 12" cable. If that's OK, cut the cable down to the desire length. If that's OK, then place the other DIP socket connector on the free end.

I do know that if you attempt to connect an unpowered 610 board to the 600 board, your 600 will not boot. But that's not what is happening here, of course.

Nice build! Please keep sharing. . .

Dave

Thanks Dave I appreciate the technical input, and it makes sense to me.

Unfortunately I don't have a spare dip plug to test it and I'd rather not disassemble my cable to try, but I'll see if I can think of something else to simulate it.

Hopefully I should have my missing parts soon and I can test it out powered up.

One question though, is it possible to run the 610 without RAM as mine is going to be a while arriving.

Thanks, and I'll keep sharing

[dave]

It is possible to run the 610 without RAM. But you won't be able to run OS65D with BASIC. I think even HEXDOS requires 12K. But you may be able to run PICODOS.

[bxdanny]

HEXDOS is the operating system that CAN run with just 8K of RAM. Pico-Dos requires 13k. (That applies to both OSI's Pico-Dos 1.1 disks and my "Enhanced" versions, although the version on the "Victory Software" disk can boot and run in 12k.)

[ronin47]

It is possible to run the 610 without RAM. But you won't be able to run OS65D with BASIC. I think even HEXDOS requires 12K. But you may be able to run PICODOS.

Thanks Dave. The primary objective being to get the 600/610 combo set up and running whilst I wait for my RAM to arrive, so it's good to know it'll run with no memory installed.

[ronin47]

HEXDOS is the operating system that CAN run with just 8K of RAM. Pico-Dos requires 13k. (That applies to both OSI's Pico-Dos 1.1 disks and my "Enhanced" versions, although the version on the "Victory Software" disk can boot and run in 12k.)

Thanks, I won't be specifically trying to run anything immediately, just get the 610 up and running. Nice to know though.