26 May
2012
26 May
'12
3:53 p.m.
Working on a PDP-11/05. The front panel appears to work, I can step through and examine
addresses in memory, and I can run the CPU and halt it. Deposit, however, does NOT work.
When the deposit switch is flipped, the LED's show the correct value, but examining
the address again shows no change to memory.
I know that this board is the problem, having swapped in a module from a working computer.
I can, with the good board, toggle a test program into core. Then, shut it off, switch in
the bad board, and the program (still in core) runs, and I can examine all areas of memory
and see it correctly.
I've only begun to glance at the schematics for the control board, but I would assume
there is some kind of write buffer that's not working correctly. I'm going to
continue to try to figure this out, but without a card extender, it's very difficult
to troubleshoot.
Anyone have any ideas on where to start? Failing that, does anyone have an extra M7261
available? :)
-Ian
27 May
27 May
11:15 a.m.
Working on a PDP-11/05. The front panel appears to work, I can step
through and examine addresses in memory, and I can run the CPU and halt
it. Deposit, however, does NOT work. When the deposit switch is flipped,
the LED's show the correct value, but examining the address again shows
no change to memory.
What I would do is to see if the Deposit switch cuases any Unibus activity
at all. Does it attempt to do a bus cycle? My _guess_ (and it's only a
guess, since I don't haev your machine here) is that it will, but that
the C0/C1 lines aren't being asserted, so it's not actualyl doing a write
(DATO) cycle.
A lot of the time, such problems are cuased by the bus buffers
Anyone have any ideas on where to start? Failing that,
does anyone
have an extra M7261 available? :)
I will pretend I never read that!
-tony
28 May
28 May
8:16 p.m.
Further testing tonight. When the deposit switch is toggled, it does increment the
address. I have verified that the processor can write to memory, by toggling in a program
with a known good control board, then swapping in the bad one and running the program. I
have also verified (with a logic probe and creative cabling) that the basic switch logic
(consisting of a couple of flip flops and a 7400) does appear to be working (chips
E97-99).
It would seem that the actual switch register/buffer is located on the data path board, so
it's not a problem with that itself.
-Ian
9:55 p.m.
New subject: I got a TK3000 //e :D
Just for records! I got a TK3000//e (our local clone of the apple //e)
with 1MB RAM, two drives and CFFA, ebaaaa!!! Iuupppiii!!! :oD
Now I just need to find a transwarp, a serial card, a parallel printer
card, a clock card and...well, I'm happy anyways :D
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
10:03 p.m.
New subject: I got a TK3000 //e :D
Pics!!
--
Dave McGuire, AK4HZ
New Kensington, PA
On May 29, 2012, at 12:55 AM, "Alexandre Souza - Listas" <pu1bzz.listas at
gmail.com> wrote:
Just for records! I got a TK3000//e (our local clone of the apple //e) with 1MB RAM,
two drives and CFFA, ebaaaa!!! Iuupppiii!!! :oD
Now I just need to find a transwarp, a serial card, a parallel printer card, a clock
card and...well, I'm happy anyways :D
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
10:39 p.m.
New subject: I got a TK3000 //e :D
In a few moments :)
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
----- Original Message -----
From: <mcguire at neurotica.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 29, 2012 2:03 AM
Subject: Re: I got a TK3000 //e :D
Pics!!
--
Dave McGuire, AK4HZ
New Kensington, PA
On May 29, 2012, at 12:55 AM, "Alexandre Souza - Listas"
<pu1bzz.listas at gmail.com> wrote:
Just for records! I got a TK3000//e (our local clone of the apple //e)
with 1MB RAM, two drives and CFFA, ebaaaa!!! Iuupppiii!!! :oD
Now I just need to find a transwarp, a serial card, a parallel printer
card, a clock card and...well, I'm happy anyways :D
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
10:49 p.m.
New subject: I got a TK3000 //e :D
Here you have:
http://www.flickr.com/photos/tabajara-labs/sets/72157629947026782/
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
----- Original Message -----
From: <mcguire at neurotica.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 29, 2012 2:03 AM
Subject: Re: I got a TK3000 //e :D
Pics!!
--
Dave McGuire, AK4HZ
New Kensington, PA
On May 29, 2012, at 12:55 AM, "Alexandre Souza - Listas"
<pu1bzz.listas at gmail.com> wrote:
Just for records! I got a TK3000//e (our local clone of the apple //e)
with 1MB RAM, two drives and CFFA, ebaaaa!!! Iuupppiii!!! :oD
Now I just need to find a transwarp, a serial card, a parallel printer
card, a clock card and...well, I'm happy anyways :D
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
11:08 p.m.
New subject: I got a TK3000 //e :D
Very nice Indeed!
/Nico
----- Original Message -----
From: "Alexandre Souza - Listas" <pu1bzz.listas at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 29, 2012 7:49 AM
Subject: Re: I got a TK3000 //e :D
Here you have:
http://www.flickr.com/photos/tabajara-labs/sets/72157629947026782/
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
----- Original Message -----
From: <mcguire at neurotica.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 29, 2012 2:03 AM
Subject: Re: I got a TK3000 //e :D
--
I am using the free version of SPAMfighter.
We are a community of 7 million users fighting spam.
SPAMfighter has removed 382 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len
The Professional version does not have this message
Pics!!
--
Dave McGuire, AK4HZ
New Kensington, PA
On May 29, 2012, at 12:55 AM, "Alexandre Souza - Listas"
<pu1bzz.listas at gmail.com> wrote:
Just for records! I got a TK3000//e (our local clone of the apple //e)
with 1MB RAM, two drives and CFFA, ebaaaa!!! Iuupppiii!!! :oD
Now I just need to find a transwarp, a serial card, a parallel printer
card, a clock card and...well, I'm happy anyways :D
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
29 May
29 May
7:40 a.m.
New subject: I got a TK3000 //e :D
On 05/29/2012 01:49 AM, Alexandre Souza - Listas wrote:
Good score! It's very clean, looks like new. Damn fine looking machine.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
7:47 a.m.
New subject: I got a TK3000 //e :D
Good score! It's very clean, looks like new.
Damn fine looking machine.
I cleaned it :) But forgot to clean the top cover :( It is a nice
machine, I love it :)
Now I just need a super serial card, a grappler+ card, a timemachine HO
card and who knows, a transwarp card :o)
Unfortunately all of them are hugely expensive in Brazil...So, time to
watch ebay :oD
11:12 a.m.
Further testing tonight. When the deposit switch is toggled, it does
increment the address. I have verified that the processor can write to
memory, by toggling in a program with a known good control board, then
swapping in the bad one and running the program. I have also verified
(with a logic probe and creative cabling) that the basic switch logic
(consisting of a couple of flip flops and a 7400) does appear to be
working (chips E97-99).
It would seem that the actual switch register/buffer is located on the
data path board, so it's not a problem with that itself.
I think if the data path from the swtiches was the problem, then the
thing would write 000000 or 177777 or something constistent to memory
every time you hit Deposit, it would not leave the memeory unchanged.
What I swould do next is see just what the Unibus is doing when you hit
Deposit. In particualr, Is MSYN plusing low (indicating abus cycle is
occuring). Do C0 and C1 do anything? You can pick these up on the E
conenctor of an SPC slot or on the Unibus terminator so it shouldn't be
too hard to test them.
My tirck for not needing an exteder board in low-ish speed machines
(PDP11s genrally qulaify!), is to pul lthe board I am interested in and
solder wires to the IC pins I am interested in montioring (Just
tack-sodler them on the track side). Put the board back in, make sure the
fee ends of the wires don't short. Then power up, and probe the free
ends. Power down, pul lthe board, resolde the wires to the next set of
points (beased on the results of the first set of tests) and so on.
I gneerally find 2 or 3 iterations lets me find the fault.
-tony
4373
days inactive
4376
days old
10 comments
5 participants
participants (5)
-
ard＠p850ug1.demon.co.uk -
ian_primus＠yahoo.com -
mcguire＠neurotica.com -
nico＠farumdata.dk -
pu1bzz.listas＠gmail.com