6 Jun
2016
6 Jun
'16
8:19 p.m.
In following this thread, and taking in my "vast" Heathkit knowledge, I can only
assume that the addition of a 'W' in the model number is to indicate a WIRED (at
the factory) Heathkit.
This may mean that the ETW-3400(a) is a wired version of the ET-3400(a).
The difference that shows between the 'a' and non 'a' version is the space
for four ram chips in the upper left visible corner of the PC board. The non-a version
can have up to 4 ram chips (for a total of 512 bytes), but the a version has two 1024x4
chips, but only 512 bytes are available.
Hope this answers some questions.
(I have an ET3400-a version).
6 Jun
6 Jun
10:58 p.m.
@Tom & All,
"In following this thread, and taking in my "vast" Heathkit knowledge, I
can only assume that the addition of a 'W' in the model number is to
indicate a WIRED (at the factory) Heathkit."
Fair enough, and it's as good a suggestion as anything heard so far. But
again, you're confusing the (very easily confused) model names..
The ET-3400 and ET-3400A are the original "trainer" kits. These are the
main computer module, with a calculator-style keyboard, 7-segment LED
display, and either 512 bytes or 1KB RAM memory. I believe that the later
'A' version also includes the 4MHz crystal-controlled system clock upgrade,
in addition to the larger RAM size.
The expansion modules are confusingly called out as ETA-3400 (note, not
ET-3400A) and ETW-3400. It's these latter two distinctions that are the
cause of my (and apparently, much) confusion. But your suggestion that the
'W' substitution refers to a factory-wired unit makes good sense, at least
in this case - because my ETW-3400 seems to have been factory built.
It doesn't have any of the tell-tale signs of kit assembly. For instance,
it appears that the board has been wave soldered and washed of flux. The
rest of the workmanship gives the same impression of factory-quality
assembly.
So maybe that's all there is to it? The ETA-3400 is kit form, and the
ETW-3400 is factory built?
On Mon, Jun 6, 2016 at 10:19 PM, Tom Watson <tsw-cc at johana.com> wrote:
In following this thread, and taking in my
"vast" Heathkit knowledge, I
can only assume that the addition of a 'W' in the model number is to
indicate a WIRED (at the factory) Heathkit.
This may mean that the ETW-3400(a) is a wired version of the ET-3400(a).
The difference that shows between the 'a' and non 'a' version is the
space
for four ram chips in the upper left visible corner of the PC board. The
non-a version can have up to 4 ram chips (for a total of 512 bytes), but
the a version has two 1024x4 chips, but only 512 bytes are available.
Hope this answers some questions.
(I have an ET3400-a version).
7 Jun
7 Jun
5:01 a.m.
On Tue, Jun 7, 2016 at 1:58 AM, drlegendre . <drlegendre at gmail.com> wrote:
@Tom & All,
"In following this thread, and taking in my "vast" Heathkit knowledge, I
can only assume that the addition of a 'W' in the model number is to
indicate a WIRED (at the factory) Heathkit."
Fair enough, and it's as good a suggestion as anything heard so far. But
again, you're confusing the (very easily confused) model names..
The ET-3400 and ET-3400A are the original "trainer" kits. These are the
main computer module, with a calculator-style keyboard, 7-segment LED
display, and either 512 bytes or 1KB RAM memory. I believe that the later
'A' version also includes the 4MHz crystal-controlled system clock upgrade,
in addition to the larger RAM size.
The expansion modules are confusingly called out as ETA-3400 (note, not
ET-3400A) and ETW-3400. It's these latter two distinctions that are the
cause of my (and apparently, much) confusion. But your suggestion that the
'W' substitution refers to a factory-wired unit makes good sense, at least
in this case - because my ETW-3400 seems to have been factory built.
It doesn't have any of the tell-tale signs of kit assembly. For instance,
it appears that the board has been wave soldered and washed of flux. The
rest of the workmanship gives the same impression of factory-quality
assembly.
So maybe that's all there is to it? The ETA-3400 is kit form, and the
ETW-3400 is factory built?
On Mon, Jun 6, 2016 at 10:19 PM, Tom Watson <tsw-cc at johana.com> wrote:
In following this thread, and taking in my
"vast" Heathkit knowledge, I
can only assume that the addition of a 'W' in the model number is to
indicate a WIRED (at the factory) Heathkit.
This may mean that the ETW-3400(a) is a wired version of the ET-3400(a).
The difference that shows between the 'a' and non 'a' version is the
space
for four ram chips in the upper left visible
corner of the PC board. The
non-a version can have up to 4 ram chips (for a total of 512 bytes), but
the a version has two 1024x4 chips, but only 512 bytes are available.
Hope this answers some questions.
(I have an ET3400-a version).
From the Modification Kit page 1
"This Modification Kit will let you interface the ET3400
and the ET-3400A Microprocessor Trainers with
the ETA-3400A or EWA-3400A Microprocessor I/O
Memory Accessory...."
".....The following steps will modify your Heath ET-3400
Microprocessor Trainer so it will operate with the
ETA/EWA-3400 Memory I/O Accessory....."
There is a manual for the ETA that includes both Tiny Basic and Wintek
monitor.
It just makes sense to me that T = Tiny Basic (and Wintek monitor), EWA
means Wintek monitor (only).
To prove this, find the manual entitled: "SOFTWARE REFERENCE MANUAL for the
MEMORY AND INPUT/OUTPUT ACCESSORY for the ET-3400 Trainer Model EWA-3400
The ETA version part number is 595-2271-01, the EWA must be close to that.
Back then, getting an extra BASIC ROM would have been a measurable expense,
especially for a school that had no use for BASIC to be included in their
trainers.
--
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg <https://twitter.com/billdeg>
Youtube: @billdeg <https://www.youtube.com/user/billdeg>
Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>
5:06 a.m.
CORRECTION
I am wrong. The W means assembled in the factory apparently.
http://heathkit.garlanger.com/catalogs/1979/Heathkit_Catalog_845.pdf
For another $47 you could by the chipset for either the W or T versions.
Sorry about that.
b
1:58 p.m.
Hey, thanks for the catalog link. It confirms that the 'W' designation
indicates factory-wired units, in the case of both the trainer and the
accessory unit. But note the difference in assembly costs between the
ETW-3400 and the EWA-3400 accessory, I'm surprised that the latter would
take any more time to build than the former, but I'm sure they had their
reasons.
And it appears that the $47.00 chip option is for the extra 3K of SRAM that
the accy. board can hold (for the max total of 4K). Both the tiny BASIC and
monitor ROMs are standard equipment, and included in the regular price - or
at least they were in 1979.
On Tue, Jun 7, 2016 at 7:06 AM, william degnan <billdegnan at gmail.com> wrote:
CORRECTION
I am wrong. The W means assembled in the factory apparently.
http://heathkit.garlanger.com/catalogs/1979/Heathkit_Catalog_845.pdf
For another $47 you could by the chipset for either the W or T versions.
Sorry about that.
b
8:47 p.m.
I've been reviewing the 'conversion' document, found here:
https://nerp.net/~legendre/heathkit/3400/ET-3400_ET-3400A/Heathkit%20ET%203…
Which describes how to modify the ET-3400/A to mate with the ETA-3400 accy
unit. For some reason, a number of details - pictorials, it seems - are
missing from the document.
All of the missing details seem to involve modification and connection of
an 'RF shield' component, which might refer to a copper tape strip which is
part of the ET-3400 package. Apparently, the they intend for a wide copper
strip to interconnect the ground planes of the two chassis..?
My sense is that the info was left out as it's unnecessary to achieve
correct operation.. more of a "the FCC made us do this" sort of thing. Can
anyone comment on the omission, and any importance it might have?
-----------------------------------------------------------------------------
(My complete Heathkit 3400 series document set is here:
http://nerp.net/~legendre/heathkit/3400/
It includes all of the scanned 3400 materials I have collected, and I
believe it is complete, less the BASIC programming course materials. All
other documents, including the self-taught courses should be present.
Please advise if anything is missing, or if you can supply the BASIC course
documents.
------------------------------------------------------------------------------
On Tue, Jun 7, 2016 at 3:58 PM, drlegendre . <drlegendre at gmail.com> wrote:
Hey, thanks for the catalog link. It confirms that the
'W' designation
indicates factory-wired units, in the case of both the trainer and the
accessory unit. But note the difference in assembly costs between the
ETW-3400 and the EWA-3400 accessory, I'm surprised that the latter would
take any more time to build than the former, but I'm sure they had their
reasons.
And it appears that the $47.00 chip option is for the extra 3K of SRAM
that the accy. board can hold (for the max total of 4K). Both the tiny
BASIC and monitor ROMs are standard equipment, and included in the regular
price - or at least they were in 1979.
On Tue, Jun 7, 2016 at 7:06 AM, william degnan <billdegnan at gmail.com>
wrote:
CORRECTION
I am wrong. The W means assembled in the factory apparently.
http://heathkit.garlanger.com/catalogs/1979/Heathkit_Catalog_845.pdf
For another $47 you could by the chipset for either the W or T versions.
Sorry about that.
b
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