Re: P112 Floppy Controller

[Fred Cisin via cctech]

On Sat, 23 Apr 2022, Craig Ruff via cctech wrote:
The P112's floppy controller is the one in the SMSC FDC37C665IR SuperIO 
chip. The data sheet states it is a 2.88 MB "Licensed CMOS 765B Floppy 
Disk Controller" and claims 100% IBM compatibility (for what that's 
worth).


2.8M (it is not "2.88" unless MB is 1024,000) means that it includes a 
1000K data transfer rate


765B means essentially the same FDC as PC (NEC 765 based)

Does it also support FM?   125K data transfer rate (TRS80, Early Osborne)

Re: idea for a universal disk interface

[Fred Cisin via cctech]

On Wed, 13 Apr 2022, Paul Koning wrote:
Indeed.  Though even that is hard for the more exotic formats, if 
original controllers are unavailable.  How would you read, for example, 
an IBM 1620 or CDC 6600 disk pack, given that the machine is hard to 
find and those that exists may not have the right controllers?  But both 
are certainly doable with a "generic" track extractor engine.  Turning 
track waveforms into data then becomes a matter of reverse engineering 
the encoding and constructing the software to do that.  This may be 
hard, or not so hard.  For example, if you wanted to do this for a CDC 
844 disk pack (RP04/06 lookalike but with 322 12-bit word sectors) you'd 
get a lot of help from the fact that the source code of the disk 
controller firmware, and the manual describing it, have been preserved.


Then as you said the real goal is to recover files, which means also 
having to reverse engineer the file system.  That too may be documented 
adequately (it is in the 6600 case, for example) or not so much (does 
such documentation, or the OS source code, exists for the 1620 disk 
operating system?).



Some projects are well beyond the reach of even the most insane of us.

I don't think that any of us here today have the ability to build a 
replacement drive from scratch.  Even with full access to the original 
construction documents.


Now, if we had NSA level of facilities, . . .
It certainly seems that it would be THEORETICALLY POSSIBLE, with an 
extreme budget, to build a high resolution device similar to the 3M 
Magnetic Tape viewer, . . . 
https://blog.adafruit.com/2020/03/01/the-magnetic-tape-viewer-see-the-sound-on-a-tape/
. . . and use it to make optical imaging of the magnetic recording, 
followed by non-trivial analysis to decode that into track images, and 
then ultimately deciphering the encoding, track structure, and then 
directory structure, . . .

It is certainly not feasible now, but someday, . . .



I have a RAMAC platter!
It is seriously FAR too damaged to consider restoring it to usable form.
I was also told that it was extensively "degaussed" when it was 
discarded (possibly by Zellerbach Paper).
100 cylinders (with 100 heads in assembled structure), holding 5 million 6 
bit characters, or a bit less than 100K per platter.

So, I am making a 24" patio table out of it (under 3/8" tempered glass).
http://www.ed-thelen.org/RAMAC/RAMAC_Plaque_v40.pdf

When Khrshchev was denied access to go to Disneyland, they took him on a 
tour of the RAMAC factory, "to make up for it".   _I_ would rather be at 
the RAMAC factory in 1959 than at Disneyland, but the Khrushchevs were 
disappointed.



--
Grumpy Ol' Fred ci...@xenosoft.com

Re: idea for a universal disk interface

[Fred Cisin via cctech]

On Wed, 13 Apr 2022, shad via cctech wrote:

The main board should include a large enough array of bidirectional 
transceivers, possibly with variable voltage, to support as much interfaces as 
possible, namely at least Shugart floppy, ST506 MFM/RLL, ESDI, SMD, IDE, SCSI1, 
DEC DSSI, DEC RX01/02, DG6030, and so on, to give a starting point.



On Apr 13, 2022, at 5:27 PM, Fred Cisin via cctech  
wrote:
Hmmm. rather than re-inventing the wheel, as we usually do, . . .
. . . 
It says "IBM", "5160" on the back panel label, although there were 
plenty of generic second sources.

The updated "5170" version of it could be more easily set up even for USB.


On Wed, 13 Apr 2022, Paul Koning wrote:
:-) But the main goal that was mentioned is device emulation, which 
existing products generally don't do.  I see the idea as a generalized 
form of David Gesswein's MFM emulator, which is primarily a device 
emulator but is also capable of reading and writing devices to capture 
everything that's on them.


The puzzle is how to make it do, say, 2311 emulation suitable to talk to 
an IBM/360, 1311 emulation for the decimal IBM 1620, or 844 emulation 
for a CDC 6600 -- to mention just a few of the more exotic cases.


You are absolutely right.
I apologize for my error.

My mindset is/was still stuck in the disk format conversion realm, of 
trying to get information (hopefully information in the form of files, not 
just data as track images) from alien media.

And, more often than not, unidirectionally.

I wasn't even thinking about the hardware emulation aspect, which is, in 
itself, fascinating.


--
Grumpy Ol' Fred ci...@xenosoft.com

Re: idea for a universal disk interface

[Fred Cisin via cctech]

. . .  and, if there is agreement to standardize the connection system for 
the "personality modules", then some of the other storage systems could be 
implemented, particularly including some of the tape systemmes.



'course, it would be a lot more fun, instead of the 62 pin card edge, to 
go with the 100 pin one that George Morrow and Howard Fullmer tried to 
standardize, . . .

Re: idea for a universal disk interface

[Fred Cisin via cctech]

On Wed, 13 Apr 2022, shad via cctech wrote:
The main board should include a large enough array of bidirectional 
transceivers, possibly with variable voltage, to support as much 
interfaces as possible, namely at least Shugart floppy, ST506 MFM/RLL, 
ESDI, SMD, IDE, SCSI1, DEC DSSI, DEC RX01/02, DG6030, and so on, to give 
a starting point.


Hmmm. rather than re-inventing the wheel, as we usually do, . . .

It may be possible to accomplish a subset of those, specifically including 
Shugart floppy, ST506/412 MFM, RLL, ESDI, IDE, SASI, SCSI by repurposing 
certain commercial hardware.


You would have a collection of boards, that you would remove/insert into a 
connector.


The main board would have RAM, and a ROM for certain basic (and BASIC?) 
functions, but would load software for various modules and output results 
to and from one or more interfaces that remain connected.


I don't doubt that you could design a far better system, but there already 
exists a crude version, ready to implement!


It has a marginal power supply, and it has a poorly designed group of 8 
62 pin connectors for the interfaces, although some of those would need to 
be dedicated for other functions of the device, including user interface 
hardware.  Some software is already available, but some crude tools are 
available for creating more.


It says "IBM", "5160" on the back panel label, although there were plenty 
of generic second sources.

The updated "5170" version of it could be more easily set up even for USB.

Re: TRS-80 Question

[Fred Cisin via cctech]

There's a 2K hole in the Model I memory map above the ROM

On Tue, 12 Apr 2022, Yeechang Lee via cctech wrote:

Is this the hole that causes stock Model I to not run CP/M?


NO.
The problem with CP/M on TRS80 is that CP/M expects RAM from location 0 on 
up.
Location 0 - FFh are used as a data structure for running programs, with 
location 100h and up as the "transient Program Area", where programs load 
and run.

TRS80 has ROM in bottom 16K.

There did exist MODIFIED CP/M ("FMG") that loaded above ROM, and ran 
programs that weren't too "hard-wired" to expect specific load location.


Parasitic Engineering (Howard Fullmer) and Omikron Mapper both made 
sandwich boards for the model 1 that moved things (under software control) 
to run "real" CP/M.  They both ALSO sold 8" drive conversions for the 
Expansion Interface.


--
Grumpy Ol' Fred ci...@xenosoft.com

Re: Commodore vic 20 poweroff

[Fred Cisin via cctech]

On Wed, 16 Mar 2022, Diedrich, Bryce via cctech wrote:
Just got a Commodore Vic-20. What is the safest way to power it off when I 
am done using it?


On Wed, 16 Mar 2022, geneb via cctech wrote:

Turn it off.


Then disconnect the power cord from the wall.
Clean the machine
Place it in a sealed container with vaccum or inert gas

Optional:  (if you are "done using it")
Post it on eBay as "R@RE"
or
place in a vault
or
drop it off at the recycling center

Re: Does anybody have documentation or know about the OKI IF800/300 a.k.a. Sumicom System 830

[Fred Cisin via cctech]

I also had a disk for Oki (don't know if same model) with the Microsoft 
Stand-Alone BASIC, instead of CP/M.


On Mon, 15 Nov 2021, pleasefixthisbrick via cctech wrote:
Unfortunately, the model 20 was a different architecture all together.  I 
have begun looking into Japanese museums.   Maybe there is more documentation 
and data in its country of origin.


I don't know where Okidata's primary markets were, but, the sample disk 
that I had came from Russia!

Re: Does anybody have documentation or know about the OKI IF800/300 a.k.a. Sumicom System 830

[Fred Cisin via cctech]

On Thu, 11 Nov 2021, pleasefixthisbrick via cctech wrote:
I seem to have the only one in America, and I am trying to find documentation 
on it.  I have already backed up ROM's and it's custom CP/M build.   I am 
looking for in depth documentation that I can reference to get this machine 
functioning and accessible online.  Hoping to set up a BBS on it.


It certainly didn't have market penetration in USA!
I did once have, and implemented in XenoCopy, a sample disk from an 
Okidata if800 model 20, which seemed to be the same as a BMC if800 model 
20 (if one more alternate name might help you find information).  I 
hadn't heard the Sumicom badging.


I also had a disk for Oki (don't know if same model) with the Microsoft 
Stand-Alone BASIC, instead of CP/M.


--
Grumpy Ol' Fred ci...@xenosoft.com

Re: Archiving otrona attache disks

[Fred Cisin via cctech]

The 96tpi ones are 800K, and should be treated like any other "Quad 
Density" CP/M disk.


On Tue, 24 Aug 2021, geneb via cctech wrote:
Just for my own curiosity, can a "typical" high-density 5.25" drive correctly 
image a 96tpi disk?


USUALLY.
Either the drive needs to be able to switch to 300 RPM,
OR the FDC needs to support 300bit per second data transfer rate,
(same as what was required for routine reading of 360K disks in the 1.2M 
drive.)

BUT, it needs to NOT automagically engage a double-step "feature".

One of my primary test machines was a "REAL" 5170.
It worked OK for "720K" 96tpi disks (what some companies called "quad 
density")


'Course, use of a 5150/5160 with a "low density" 96tpi drive, such as 
Shugart/Panasonic/Matsushita 465, Mitsubishi 4853, Teac 55F, Tandon 
TM100-4, or similar avoids that particular potential (but not common) BIOS 
issue.

Re: Archiving otrona attache disks

[Fred Cisin via cctech]

On Tue, 24 Aug 2021, Bill Degnan wrote:

Fred,
Just for the purpose of imaging the disks, is there any reason I cant treat
these disks like any other 5 1/4" cpm 360k disk?
Bill


Treat them just like any other 5.25" MFM CP/M disk.
IIRC, the 48TPI ones are 400K, with 512 bytes per sector, 10 sectors per 
track.


The 96tpi ones are 800K, and should be treated like any other "Quad 
Density" CP/M disk.


They also had a 96tpi MS-DOS format.  Same thing, but obviously, with an 
MS-DOS, rather than CP/M file system.



For those who may not remember the Otrona Attache, it was smaller and 
lighter than the other luggables.


They had an advertisement with a Charlie Chaplin look-alike, comparing 
carrying it VS a 5150 (on a card table) down a broad set of stairs (in 
front of a capitol building?).  IBM had been using the "Little Tramp" in 
their advertising, and asserted OWNERSHIP of the Charlie Chaplin "Little 
Tramp" character and image, and made them cease and desist.  I can't find 
an image, nor even a mention, with GOOGLE.


--
Grumpy Ol' Fred ci...@xenosoft.com

Re: Archiving otrona attache disks

[Fred Cisin via cctech]

On Fri, 20 Aug 2021, Bill Degnan via cctech wrote:

Is there a simh for the otrona attache?  I have some.disk images created
with Dunfield's utility..if not I will try to read them by using the Zorba
portable, which is pretty good with varied formats.
Bill


Otrona is fairly straightforward for format conversion.
CP/M and MS-DOS.  There might have been other operating systems for them, 
but I didn't run into any.

They had 40 track and 80 track drives.
512 bytes per sector, so they can be done using Int13h, without even 
needing Int1Eh.

10 sectors per track;  inter-sector gaps were tight but not unreasonable.
I don't remember whether they were numbered 0 - 9 or 1 - 10

Re: Odd punched cards

[Fred Cisin via cctech]

Aperture cards (piece of 35mm micro-film mounted in card)
(As opposed to Emmanuel Goldberg's "Rapid Selector", or Vannevar Bush's 
"Memex")


Round hole Univac/Remington-Rand 90 column
There was folklore that IBM had PATENTED their rectangular hole shape, and 
the use of a wire brush and brass roller reader


Optical mark cards

IBM System/3 96 columns undersized cards

"Marginal" knitting needle cards(Royal McBee, EZ sort, Zato-code, 
keysort,...); some even used two depths of notch



It was right about the time of LBJ's re-election that IBM started to round 
the corners on cards



On Thu, 23 Apr 2020, Mike Stein via cctech wrote:


How about 96 column and EPC (Edge Punched) Cards?

Re: P112

[Fred Cisin via cctech]

On Wed, 4 Dec 2019, Bill Gunshannon via cctech wrote:

Along this line I have solved one problem.  I mentioned INIT in
RSX180 printing gibberish on the screen when trying to init a
hard disk partition where it had worked on a floppy.  Problem
was the size of the partitions.  I had tried just making one
partition for the test I learned that FDISK will make partitions
too big for any of the P112 OSes.  I now have a hard disk with
5 partitions to play with.  On to the  next problem.


Is it a specific size limit?
(something on the order of number of bits for block number?)

RE: advice upcoming visit to Bletchley Park / comp museum

[Fred Cisin via cctech]

On Sat, 6 Jul 2019, Dave Wade via cctech wrote:
However, the route involves the M25 via Heathrow and that has frequent 
blockages so IMHO it’s a risky option.


I've never been there, so have no first-hand knowledge.  But, "Good Omens" 
by Pratchett and Gaiman says,
"Many phenomena - wars, plagues, sudden audits - have been advanced as 
evidence for the hidden hand of Satan in the affairs of Man, but whenever 
students of demonology get together the M25 London orbital motorway is 
generally agreed to be among the top contenders for Exhibit A."


Is it really that bad?

It would seem like the museum would be justification for an extra day on 
the trip.


(When we went to the National Auto Museum that had been built out of the 
remains of the Harrah's Club Collection, we kept it open ended.)


--
Grumpy Ol' Fred ci...@xenosoft.com

Re: Possible PUTR bug?

[Fred Cisin via cctech]

I wish that I were to have met you 40 years ago!
Learning that stuff by error, error, error, trial, and error was 
inefficient.


--
Grumpy Ol' Fred ci...@xenosoft.com

On Sat, 11 May 2019, allison via cctech wrote:

My Solution is easier, least for me.

I have a few Z80 CP/M machines with 765A in it and if it can't read it
its likely due to being hard sectored or M2FM.  I has 3.6, 5.25 and 8"
and  the 5.25 are Teac FD55gfh which are dual speed and can do all
modes. With my own software and utilities it does whatever even RX180,
RX50, RX33, and RX22/23 formats from the DEC pool.

The PC machine for when that stuff is needed is a DELL pizza box that
has 32mb of ram and 486dx/66 (ISA/ISA16) and can run dos though NT4 as
needed as I have a buttload of ST3660As as media for them (have two as a
spare).  That machine uses a combo IO controller for the FDC seems to do
what I ask of it.  Also an old Compag with similar features and PII and
32MB and also does Ethernet but the disk controller is a newer ISA16
using a combo chip and most of the combo chips after late 90s-ish seem
to have an even shorter VFO sync window (flash blindess).

I neither expect nor desire modern machine with anything past NT4 to
behave well with old disks.  Though Mini-ITX boards all seem to support
everything and anything and have all the legacy ports.  They all run
linux and if needed a partition (60mb of disk is trivial) for MSdos
6.22 or freedos.

Oh, unless its under threat the OS is linux, freedos, or if required XP
Though the latter is usually under VMware or Virtualbox on Linux..  I
just got tired of all the winders hassles and requirements for insane
hardware needs every few years.  Most stuff runs fine under dosemu or wine.

As to RT11, I have run mostly V5.0x and as needed if a device required
it a later driver borrowed from V5.04 or later.  It just seems to work
with out much pain.

As to running a RX50 on a PC...  That drive was a neat thing but its
mostly the interface is incompatible with most standard floppies and
a FD55A/B or any of the 48tpi 40 track drives will read and write the
media.  I make a point of only using it on PDP-11 as transfer media,
its low density so its marginal for much.  Keep in mine that drive
select is used to select the A or B drive of a RX50 there is no side.
They had a terrible track record for reliability.  I can put Two RX33
[teac fd55gfh] in the same space and store more.  Some to think of it
most Late PC 5.25 and 3.5 inch drives are incompatable with old standard
[TM100 and that era] as many do not have a 1 of 4 drive select jumper
and use the funky PC only twist cable.

I neatly sidestep all of the cruft and hacks needed for super wizbang
winXP and later machines.  I figure if I'm going to play with old
hardware I need to retain the old hardware to maintain them.  So I
retained the best of the best old PCs as they bulk of them are crap.
I buy new hardware that is not neutered.  Mini/Micro-ITX board with
atom or celeron CPUs (really all that's needed) are cheap and easily
built up into linux boxes or if you must any of the older 32 bit
winders incantations.


Allison

Re: Daisywhell typewriter emulating a TTY

[Fred Cisin via cctech]

On Wed, 10 Apr 2019, Chuck Guzis via cctech wrote:

Aw, that's too bad!  The original Model I (CADET) 1620 had a console
typewriter (was it based on the IBM Model B electric?) that gyrated
enough, particularly on carriage returns, that made you wonder if it was
going to fly to pieces at any time.  It was all part of the experience.


Immaculately maintained equipment, such as at the CHM, also doesn't have 
the burnt oil smell that used to be associated with real world EAM.

Re: Rainbow 100 PSU capacitor list

[Fred Cisin via cctech]

The circuit breaker is there to reduce the chances that a problem turns 
into a disaster.


Although it IS possible to have a defective circuit breaker that is "false 
tripping", or thinking that it has an overload at normal amperages, that 
is unlikely.


I'm afraid that it is time to start by checking for shorts to ground, 
etc., without continuing to let it happen.  Starting with whatever the 
circuit breaker is trying to protect.




On Tue, 5 Mar 2019, Alan Perry via cctech wrote:


Yes, with the power supply disconnected from the mobo, it pops.

alan

On 3/5/19 3:43 PM, Warner Losh wrote:
If you disconnect the power supply from the motherboard, disks, etc, does 
it still pop? If so -> bad power supply. If not, reconnect one at a time 
and see if it is load based (eg each of them connected alone causes it). 
If it is purely load based, then it's a bad ps). If there's one thing that 
causes it to pop, there's an issue there. If it is the mobo, you might 
also try w/o the VR201 connected, since if that's pulling too much power, 
it can cause a PS overload (though I've never had this issue, I've read 
about it years ago).


Warner

On Tue, Mar 5, 2019 at 2:56 PM Alan Perry > wrote:


OK, got back to this ...

Plugged in the Rainbow 100. Flipped the power switch. No LEDs lit.

There is a white circuit breaker on the power supply. When I
switch on the power, it pops out. I switch off the power, reset
the breaker, switch on the power and it pops out again.

alan

Re: Origin of 'Straight 8' name

[Fred Cisin via cctech]

On Fri, 21 Dec 2018, Chuck Guzis via cctech wrote:

I suspect the same common connection to "turbo", popularized by the auto
marketeers.
On the other hand, I've never seen a computer advertised with  a
"Turbo-Hydra-Matic" or "Dynaflow" feature.


such as "turbo LAG"

Should look around the yards for insignia, such as the Subaru
"Turbo XT 16"

Re: Looking for North star software

[Fred Cisin via cctech]

You "get it into a NorthStar", by already booting the NorthStar to
CP/M, and using PIP.


On Tue, 3 Jul 2018, allison via cctech wrote:

NO matter what first you have to boot the horizon and if you lack
prepared media its a hard stop.
Mike Douglass solved it by putting an Eprom on the ZPB-A as there is a
spot for a 2708 1K part.
He made up a header to use more common signal voltage parts like
2716/2732 and so on.
With a machine language monitor that allows loading bytes to memory the
process is then easy.
Me I cheated and used a spare 64K memory board that used 2kx8 parts and
put an eprom (2716) in
the F000H space.  Change the CPU boot address jumpers from E800/E900 to
F000h and now
you can talk to it via serial port.


Thanks

That answered several questions that I was wondering about!

--
Grumpy Ol' Fred ci...@xenosoft.com

Re: Looking for North star software

[Fred Cisin via cctech]

On Tue, 3 Jul 2018, Stephen Pereira via cctech wrote:

I believe that Mike Douglas has a utility program that you can get into a 
Northstar Horizon, and then it can receive a .DSK image sent from the terminal 
and it will write the disk for you in the Horizon.
It’s called PCtoFlop and I think he has it in his archive here:
http://deramp.com/downloads/north_star/ 

Good luck!


You "get it into a NorthStar", by already booting the NorthStar to 
CP/M, and using PIP.


It looks like an excellent way to handle more images, including N*-DOS, 
AFTER you have CP/M working.

Re: Ciarcia Micromint (was: Steve Garcia / Micromint SB180

[Fred Cisin via cctech]

On Sun, 2 Jul 2017, John Wilson wrote:

That sounds like the MPX16?  I thought the SB180 was a Z180 thing.


You're right.

Sorry
thinking about the wrong one.

Ciarcia Micromint (was: Steve Garcia / Micromint SB180

[Fred Cisin via cctech]

It was Ciarcia, not Garcia

It was designed for reasonable MS-DOS compatability, with a terminal.
Then Ciarcia released a keyboard interface ISA card to be closer to PC.
9 slots with the 5 slot spacing of the 5150 case (not the 8 slot spacing 
of 5160), with the additional ones in between - no good for thick/double 
cards.



On Sun, 2 Jul 2017, GerardCJAT via cctech wrote:


Remember it ?

I have an almost brand new one, powered only half dozen times. ( was running 
CPM ...  Good old days   ;-)   )

It is free to a good home, but I expect you to pay packaging and shipping from 
FRANCE

I do not know if you can contact me off line.  :-(   Please, try and let me 
know  !!

Re: TRS-80 Model 1 Expansion Interface question?

[Fred Cisin via cctech]

On Mon, 20 Mar 2017, Win Heagy via cctech wrote:

But, the FD1771 IC, for some reason, was removed from an otherwise
apparently functional EI.
http://imgur.com/a/3NzOh
Is there any reason why this chip would be removed?  I see a number of them
on ebay for around $25.  The expansion interface hardware manual indicates
it is an FD1771B-01, but the service manual indicates a couple
possibilitiesFD1771 A/B -01 -11.  Any considerations to look for here?



Some owners replaced the 1771 with a daughterboard that contained a 1771 
plus a better data separation circuit.  The 1771 included internal data 
separation, which WD advised not to use.

"EVERYBODY" used one of those.
Before selling the Expansion Interface, the previous owner might have 
removed the data separator and sold it separately.


Some owners replaced the 1771 with a daughterboard that contained a 1771 
plus a 179x, called a "Doubler".  That added double density (MFM) support. 
The Doubler included a 1771 because the 179x was incapable of writing some 
of the address marks that Model 1 TRSDOS used in its disk format.

"EVERYBODY" used one of those.
Before selling the Expansion Interface, the previous owner might have 
removed the Doubler and sold it separately.


Both the Data Separator and the Doubler COULD HAVE used the 1771 that was 
taken out, but usually came with one already installed.
1) it made for one less prying out, bending pins and reinstalling with 
bent pins or backwards

2) it meant that there was a known good chip going in.


Some owners replaced the 1771 with an aftermarket daughterboard that 
contained a 1771 plus some circuitry to do 8" SSSD.  Often that was 
accompanied by a sandwich board for the Z80 in the CPU to remap memory for 
CP/M, and a CP/M for it.

(such as Parasitic Engineering, and Omikron Mapper)
"not EVERYBODY" used one of those.
Before selling the Expansion Interface, the previous owner might have 
removed the adapter and sold it separately.
(There also existed a "remapped" CP/M for the TRS80 that would work 
without the hardware remapping, although in general no known 
commercial software worked with that setup.)




In addition to the 1771, does your Expansion Interface include the "RS232 
board"?  A Radio Shack Computer Store manager asserted that any 
incompatabilities with the standard were legitimate, "because OUR RS-232 
board is RADIO SHACK 232"
Before selling the Expansion Interface, the previous owner might have 
removed the adapter and sold it separately.



There were a few modifications to the EI over time.
The first version had a simple straight through cable.
Then they made some changes and switched to a cable with a circuit box in 
the middle of it.
Then they made some changes and switched to a cable with a circuit box in 
the middle of it, plus a small second cable.
Then they made some changes and switched to a simple straight through 
cable.
Make sure that you use the appropriate cable(s) for the level of changes 
that were made to yours.


To keep reliability, do not plug/unplug and move the CPU and the EI.
If you are going to do so, then bolt both pieces to a piece of plywood. 
RIV-NUTS or NUTSERTS into holes drilled into the bottom of the EI and CPU.



You did not HAVE TO put the power supply for the CPU into the compartment 
in the EI.  If you do, cutting a notch in the case means that you can tuck 
the excess cord in there to have 3" of power cord between the EI and CPU, 
instead of a couple of feet going out the BACK and around to the front.



The RCA TV set that Radio Shack used as a monitor had a great big empty 
space where the tuner used to be.  Plenty of room for a disk drive, or a 
pair of half-height drives.  Mu-metal surround was kinda important.


The CPU needed a trivial modification to add lower-case.  Often 
accompanied by adding a "Control key", and sometimes a mod to give reverse 
video.  Remember to put glyptol on the screw after making modifications, 
since warranty was void if there wasn't any glyptol.



--
Grumpy Ol' Fred ci...@xenosoft.com