8250 faulty drive

[dave_m]

@Giobi:
Try this:
- Insert your adapter with the 2764 into the 8032's A socket (UD11) with all pins connected.
- Turn on the 8032 and type:
S=0:FOR X = 10*4096 to X+4095:S=S+PEEK(X):NEXT: ? S

After a few seconds it should give you a total of 485835.

If you like, lift pin 21 of the adapter or pin 23 of the 2764, connect it to GND (pin 12 or 14) and run the above again.
This time you should get 477492.

Mike,
Is pin 21 of the 2364 the A12 address line? If so then shouldn't we be lifting and grounding pin 2 of the 2764 rather than pin 23 (A11)? I'll admit I am not familiar with the adapters being used.

 

[giobbi]

Giovi,
Vice being a software simulator only cares about binary files not physical devices. Vice expects a 4K binary in the A000 socket so it apparently only uses the lower half of the binary file. That is the half equivalent with with pin 21 grounded (A12) of the 2364 ROM.

aaaaah, yes, it makes sense. Thank you Dave!

 

[MikeS]

Mike,
Is pin 21 of the 2364 the A12 address line? If so then shouldn't we be lifting and grounding pin 2 of the 2764 rather than pin 23 (A11)? I'll admit I am not familiar with the adapters being used.

I knew I could count on you. Yes, of course! I did test it and originally just specified the 2364 pins (12 and 21); then I just added the usual 2 for the 2764, forgetting that the adapter reroutes pin 21 to pin 2. :confused5:

@ Giovi: Hope I didn't waste too much of your time with that... :ashamed:

:wallbang:

 

[giobbi]

I knew I could count on you. Yes, of course! I did test it and originally just specified the 2364 pins (12 and 21); then I just added the usual 2 for the 2764, forgetting that the adapter reroutes pin 21 to pin 2. :confused5:

@ Giovi: Hope I didn't waste too much of your time with that... :ashamed:

:wallbang:

Nope, in any case after your hint I supposed the ROM was broken and this allowed me to fix the digital board. I only need to fix the last problem with d0 and I've done! As usual, you boys helped me a lot and without your help and your hints I wouldn't solve the issues....

About wasting time, actually I still have a big debt with you all; but, in any case, if you're feeling bad for that, you can always help me with the next drive, LOL (just kidding, I still waiting for the 2764 eproms I ordered)

:D

 

[giobbi]

Passive adapters like yours will work to replace most 24 pin ROMs such as in the VIC, C64 etc. and even the IBM PC with 28 pin (E)EPROMs, but just rearranging the pins is not enough in an 8x50. AFAIK pretty well all (E)EPROMs are selected with a low chip select, but for some reason the 2364s used in the 8x50 are programmed to be selected with a high chip select, so you have to invert it somehow; is that what you are doing?

Mike, Dave, a question: do the 1541 drive also need high chip select like 8x50 ?

 

[dave_m]

Mike, Dave, a question: do the 1541 drive also need high chip select like 8x50 ?

There seems to be a lot of variations in boards over the years in regard to the 1541 family of drives. But all the ones I've seen in a quick survey have negative going enables.

See Zimmer

 

[MikeS]

There seems to be a lot of variations in boards over the years in regard to the 1541 family of drives. But all the ones I've seen in a quick survey have negative going enables.

See Zimmer

I believe you're right.

So, are all the 8x50 problems and ROM checksum issues solved now?

 

[giobbi]

Dave, Mike, thank you. So I can use a "normal" (passive) adapter 2764 -> 2364, right?

I believe you're right.

So, are all the 8x50 problems and ROM checksum issues solved now?

if you mean the 8250, the d1 works fine while d0 doesn't. However I put it in a corner for now, I will come back on it later.
I still have an 8050 to fix, but I'm waiting the 2764 eproms I ordered and it will take a while.

 

[MikeS]

Dave, Mike, thank you. So I can use a "normal" (passive) adapter 2764 -> 2364, right?

AFAIK, yes. Too bad you didn't ask yesterday, I had 3 1541s open beside me.

if you mean the 8250, the d1 works fine while d0 doesn't. However I put it in a corner for now, I will come back on it later.
I still have an 8050 to fix, but I'm waiting the 2764 eproms I ordered and it will take a while.

Too bad again; I have 100+ here and would happily get rid of some...

 

[giobbi]

AFAIK, yes. Too bad you didn't ask yesterday, I had 3 1541s open beside me.

no problem, I was just asking a confirmation but I also believe I can use normal adapters as told in a site I've seen.

Too bad again; I have 100+ here and would happily get rid of some...

LOL, the fact is: I'm quite compulsive, and eBay doesn't help me in that, it's too easy to order and pay
Next time I will ask you

btw have you some 6550 PET ram? (I know that probably not, but...

cheers,
Giovi