24 Feb
2014
24 Feb
'14
10:12 a.m.
From: Chuck Guzis <cclist at sydex.com>
I've long thought that the strangling of the bus done on the TI 99/4
home PC was quite possibly motivated by TI's not wanting to compete with
its own 990 series of computers. The cost of a TI 990/4 was
considerably higher than a 99/4, even though both use the same MPU.
I have heard & read this enough times to think there's something to it.
Wouldn't be the first time this sort of thing has been done.
I find the I2L versions of the 9900 far more
interesting as far as chips
go. They were used quite often in military gear, not as devices offered
to the general unwashed. In a similar way, one did not see the
Fairchild 9940 in much general audience gear.
Yes. You can debate how good a general purpose processor the 9900 is, but
it was proven to be a very good embedded controller. The memory mapped
registers and workspace swapping made real time context switching a breeze
compared to more conventional designs.
From: John Many Jars <john at yoyodyne-propulsion.net>
Basically, my dad bought the wrong thing. It cost
about 1/2 what an
Apple //+ would have cost, and was about 1/8 as useful.
Ha! That is *exactly* how I ended up with my own 99/4.
KJ
24 Feb
24 Feb
11:49 a.m.
If you were lucky, it might overheat and set fire to
your house. Then
you could claim the insurance money.
I noticed the video chip was covered with a white gunk in a couple of the
units I opened in order to reconstitute my working one. I understand this
is some kind of substance which aids with cooling so that chip at least
runs very hot.
Terry (Tez)
11:59 a.m.
On Feb 24, 2014, at 2:49 PM, Terry Stewart <terry at webweavers.co.nz> wrote:
White gunk will hurt cooling, not help (white interferes with radiational cooling).
I take it you?re assuming it is silicone thermal grease. That?s plausible. But silicone
grease only helps cooling if you stick it (in a *thin* layer) between the device and a
suitable heat sink. The heat sink actually does the cooling.
paul
If you were
lucky, it might overheat and set fire to your house. Then
you could claim the insurance money.
I noticed the video chip was covered with a white gunk in a couple of the
units I opened in order to reconstitute my working one. I understand this
is some kind of substance which aids with cooling so that chip at least
runs very hot. 
12:10 p.m.
On Mon, 24 Feb 2014, Paul Koning wrote:
On Feb 24, 2014, at 2:49 PM, Terry Stewart <terry at webweavers.co.nz> wrote:
White gunk will hurt cooling, not help (white interferes with
radiational cooling).
I take it you?re assuming it is silicone thermal grease. That?s
plausible. But silicone grease only helps cooling if you stick it (in a
*thin* layer) between the device and a suitable heat sink. The heat
sink actually does the cooling.
The heat sink paste is typically only used if there's some kind of
mu-metal RFI shield in place over the board - a good example of this is in
the Commodore 128 where bent out tabs in the mu-metal shield act as
heatsinks - each chip that has a tab resting on it has a small amount of
white heat shrink paste on it.
g.
--
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http://www.f15sim.com - The only one of its kind.
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A Multi-Value database for the masses, not the classes.
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If you
were lucky, it might overheat and set fire to your house. Then
you could claim the insurance money.
I noticed the video chip was covered with a white gunk in a couple of the
units I opened in order to reconstitute my working one. I understand this
is some kind of substance which aids with cooling so that chip at least
runs very hot.
12:37 p.m.
I take it you're assuming it is silicone thermal
grease. That's
plausible.
But silicone grease only helps cooling if you stick it
(in a *thin* layer)
between the device and a suitable heat sink.
The heat sink actually does the cooling.
Ah yes. Actually there is a heat sink on the top part of the case that
sits on this chip when the case is closed. I didn't notice that.
http://www.mainbyte.com/ti99/console/console_10.jpg
(from http://www.mainbyte.com/ti99/console/console_dis.html)
Terry (Tez)
On Tue, Feb 25, 2014 at 8:59 AM, Paul Koning <paulkoning at comcast.net> wrote:
On Feb 24, 2014, at 2:49 PM, Terry Stewart <terry at webweavers.co.nz> wrote:
this
If you
were lucky, it might overheat and set fire to your house. Then
you could claim the insurance money.
I noticed the video chip was covered with a white gunk in a couple of the
units I opened in order to reconstitute my working one. I understand is some kind of substance which aids with cooling
so that chip at least
runs very hot.
White gunk will hurt cooling, not help (white interferes with radiational
cooling).
I take it you're assuming it is silicone thermal grease. That's
plausible. But silicone grease only helps cooling if you stick it (in a
*thin* layer) between the device and a suitable heat sink. The heat sink
actually does the cooling.
paul
12:56 p.m.
I was interested in getting a TI-99/4A system for a while, but after I
finally got a couple of systems with PEB (Periperal Exansion Box)
floppy drive setups I never got excited enough to do anything with
them and moved them along to other collectors.
If you ever do get a floppy drive setup you might want to take a look at this:
ftp://ftp.whtech.com/pc%20utilities/TI99-PC_3.0.0.zip
I never got around to trying it myself. It looks like it could be used
to write TI-99/4A floppy disks directly from a PC and there is a large
collection of archived floppy disk images on that site.
-Glen
1:10 p.m.
On 02/24/2014 12:37 PM, Terry Stewart wrote:
Well, there you go, but it strikes me as some pretty sloppy engineering.
You really need the cover to make firm contact with the top of the
cerDIP package. This looks like it uses a generous glob of the stuff to
fill in the obvious gaps.
It might have been better to use a separate firmly-attached heatsink or
at least some sort of spring clip to make contact with the IC package.
--Chuck
1:24 p.m.
On Feb 24, 2014, at 4:10 PM, Chuck Guzis <cclist at sydex.com> wrote:
It might have been better to use a separate
firmly-attached heatsink or at least some sort of spring clip to make contact with the IC
package.
That's certainly what my C64 has. There's a copper flat spring attaching
the VIC to the lid of its can.
- Dave
25 Feb
25 Feb
3:13 a.m.
On 02/24/2014 04:10 PM, Chuck Guzis wrote:
On 02/24/2014 12:37 PM, Terry Stewart wrote:
Well, there you go, but it strikes me as some pretty sloppy
engineering. You really need the cover to make firm contact with the
top of the cerDIP package. This looks like it uses a generous glob of
the stuff to fill in the obvious gaps.
It might have been better to use a separate firmly-attached heatsink
or at least some sort of spring clip to make contact with the IC package.
--Chuck
The problem is they have a cover over it and it contained the heat
unless you copled the heat source to the cover.
The base chips in air have no need for a heat sink.
The TI990/4 mini was more expensive because it had peripheral of
substance and more ram, way more.
Everyone seems to forget RAM was costly at one time.
Allison
24 Feb
24 Feb
2:09 p.m.
I noticed the
video chip was covered with a white gunk in a couple of the
units I opened in order to reconstitute my working one. I understand this
is some kind of substance which aids with cooling so that chip at least
runs very hot.
White gunk will hurt cooling, not help (white interferes with
radiational cooling).
I take it you?re assuming it is silicone thermal grease. That?s
plausible. But silicone grease only helps cooling if you stick it (in a
*thin* layer) between the device and a suitable heat sink. The heat
sink actually does the cooling.
4:41 p.m.
On 02/24/2014 05:09 PM, Tony Duell wrote:
>> I noticed the video chip was covered with a
white gunk in a couple of the
>> units I opened in order to reconstitute my working one. I understand this
>> is some kind of substance which aids with cooling so that chip at least
>> runs very hot.
> White gunk will hurt cooling, not help (white interferes with
> radiational cooling).
>
> I take it you?re assuming it is silicone thermal grease. That?s
> plausible. But silicone grease only helps cooling if you stick it (in a
> *thin* layer) between the device and a suitable heat sink. The heat
> sink actually does the cooling.
Having several its white silicone based grease
to transfer heat from the
chips
to the the surrounding shield, which is there for EMI/RFI prevention.
Allison
I seem to remember in the TI99/4A that I had apart
there is a metal
screen (shield) around the PCB. A couple of the ICs (I forget which ones)
had silicone grease on them which effectively allowed them to use this
screen as a heatsink. I am not sure it was a very good heatsink, but..
-tony
25 Feb
25 Feb
1:09 a.m.
I picked this link up from Jimmy Maher's article on
the home computer
wars. The article below is from Texas Monthly April 1984, it's a fairly in
depth look at the TI-99 failure.
That was a great read. Thanks for posting
Terry (Tez)
On Tue, Feb 25, 2014 at 1:41 PM, allison <ajp166 at verizon.net> wrote:
On 02/24/2014 05:09 PM, Tony Duell wrote:
>> I noticed the video chip was covered with
a white gunk in a couple of
the
>> units I opened in order to reconstitute
my working one. I understand
this
>> is some kind of substance which aids with
cooling so that chip at least
>> runs very hot.
> White gunk will hurt cooling, not help (white interferes with
> radiational cooling).
>
> I take it you're assuming it is silicone thermal grease. That's
> plausible. But silicone grease only helps cooling if you stick it (in a
> *thin* layer) between the device and a suitable heat sink. The heat
> sink actually does the cooling.
Having several its white silicone based grease
to transfer heat from the
chips
to the the surrounding shield, which is there for EMI/RFI prevention.
Allison
I seem to remember in the TI99/4A that I had
apart there is a metal
screen (shield) around the PCB. A couple of the ICs (I forget which ones)
had silicone grease on them which effectively allowed them to use this
screen as a heatsink. I am not sure it was a very good heatsink, but..
-tony
3721
days inactive
3722
days old
11 comments
9 participants
participants (9)
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ajp166＠verizon.net -
ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
fraveydank＠gmail.com -
geneb＠deltasoft.com -
glen.slick＠gmail.com -
paulkoning＠comcast.net -
seefriek＠gmail.com -
terry＠webweavers.co.nz