Hi all,
Anybody know what type of drive I can connect to the popular North Star
MDS-AD3 S-100 disk controller board?
I'm confused with all of this old floppy terminology. I know single vs.
dual density (FM vs. MFM) is determined by the controller, and soft vs.
hard sectoring is determined by the controller, so neither of these
should matter as far as the drive is concerned.
What bothers me is single vs. double sided and all of those jumpers on 5
1/4" drives. Will dual sided drives work on single sided controllers,
with only one side operating? Do those jumpers need to be set
differently for different controllers, and how would I find
documentation for the various brands (I'm sure I wouldn't!)
Any advice appreciated,
thanks
Kai
>I see a LOT of traffic about restoring and collecting old computers,
>and the typical member here is one who has a large collection of
>different machines, but except for a rare question about boot disks,
>there isn't much said about using these machines. When I turn on my
>99/4A or Geneve, it isn't primarily to bask in a nostalgic glow, but
>to write something or balance my budget or do some programming.
>Certainly the nostalgic glow is there, and it adds a dimension to
>the computing experience that peecee devotees cannot understand. But
>it IS my primary workhorse, not just a desk queen.
That's part of what I love about my Apple IIGS. I'm the original
owner. I know what this machine has done for me and continues to do
for me. I love its simplicity. In the rare event of a crash, I pretty
much know what the problem is, because I know the machine much better
than anything Wintel came up with or any of the Macincrash line.
>Don't get me wrong; I love to hear about these old machines, so keep
>those messages coming. But I would like to hear from others out there
>who use their obsolete machines (I prefer "non-mainstream machines")
>for practical, everyday, household computing uses.
Well, I'm a college student, so I use my IIGS for writing papers
(though I transfer them to a Mac to print because my Imagewriter II
isn't in good shape - I'll get around to fixing it one of these days).
Mainly, I use it to connect to the campus computer system. I've also
used it to run a BBS, play games, program - more than most people do
with their PeeCees.
>In fact, I'm wondering how widespread my idea is (shared by a
>few, apparently) that the smaller, simpler machines really are well
>suited for home use, and you don't need a high-end peecee for nearly
>everything you want to do.
You bet it is! This machine does everything I want or need it to do
(or at least is capable of it, if I'm too cheap to buy things like a
laser printer).
--
Andy Brobston brobstona(a)wartburg.edu ***NEW URL BELOW***
http://www.wartburg.edu/people/docs/personalPages/BrobstonA/home.html
My opinions do not necessarily reflect the opinions of Wartburg College
as a whole.
Dan:
Although I have never seen one up-close, a company that I formerly worked for
had a System 36. I think that it is one of IBM's older mainframes/minis that
was the predecessor to the AS/400 (our S36 software ran unmodified on the
AS/400).
It's based on a TwinAx-based network and has terminals connected to it with
snappy names such as the "3270" and the "5250". Line printers are also Twin-Ax
based.
I hope that this is the same one that I was thinking about (otherwise, ignore
the above <g>).
------------------------
Rich Cini/WUGNET
- ClubWin Charter Member (6)
- MCPS Windows 95/Networking
>And it was more than just the machine itself, but the culture that
>spawned around it. The culture I am referring to mainly is the BBS
>culture with all its lingo, the pirate groups who banded together and
>cracked software, the holy wars with other computers.
>The history behind the machine is what I am most interested in. What
>company built it, what year it came out, what technology it used (its
>processor, RAM, etc), what its predecessor and successor were, etc. I
>like to know each machines historical perspective.
Part of the thrill I have of being a TI junkie is BEING part of that
history! The interesting part of the 99/4A is not so much the level
of technology involved (although it IS there, relative to other home
computers of the period) as the legend of how TI could make a market
run with it, strain every nerve in true TI tradition, and then
dramatically dump it when the effort finally proves to be too much.
And now, I am part of the history of the TI-99/4A too, by perversely
supporting it in preference to other (e.g. modern, more capable)
platforms.
--
**********************************************
* David Ormand *** Southwest 99ers *
* dlormand(a)aztec.asu.edu *** Tucson, Arizona *
**************************** TMS9900 Lives! *
>Files are linked lists of blocks. The sector header of each sector on the
>hard disk contains pointers to the previous and next blocks in the file,
>along with some other info that I've forgotten
>Files may be sparse - the fact that block n exists does not mean that
>block n-1 does
>Block 0 of each file (I think, maybe block -1) contains the 'file
>descriptor' - bascially an i-node.
>Negative block numbers are the file allocation map. You can use this to
>quickly find any block in the file without following the links.
Hi,
today I got a special german (?) computer. It is a "SIEMENS PC100". But inside
there is a board labled "R6500 ADVANCED INTERACTIVE MICROCOMPUTER"
it is made by "ROCKLWELL" with a small (thermo?) printer a one-line
display. Is this one of the legendary AIM65-Machines?
At 06:47 PM 6/25/97 -0700, you wrote:
>I'm not so sure that "everything" supports TIFF. After a little looking,
>I couldn't even find a TIFF file to test with xv.
And my experience has been that TIFF is not always the same, especially Mac
vs. PC.
>Is there a reason that postscript cannot be used? Most of the schematics
>out there that I have seen have been postscript files.
[...]
>Why not use postscript for publishing the formatted documents?
Postscript is fine for Macs, not so great for PC's, and probably unusable
for most older (pre-pc) machines. I'm not so worried about the images, but
the formatted text should be kept readable. I'm not super-familiar with
RTF, but isn't it just tags (like HTML)? If so, than a "reader"(?) could be
written, even for CP/M or TRS-DOS or whatever...
--------------------------------------------------------------------- O-
Uncle Roger "There is pleasure pure in being mad
sinasohn(a)crl.com that none but madmen know."
Roger Louis Sinasohn & Associates
San Francisco, California http://www.crl.com/~sinasohn/
Monitor Jack (all but 400, North American 600XL, XE Game System):
3 1
5 4
2
1. Composite Luminance (not on North American 600XL's)
2. Ground
3. Audio Output
4. Composite Video
5. Composite Chroma (not on 800XL,1200XL; grounded on 600XL)
----------
> From: Bill Girnius <thedm(a)sunflower.com>
> To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
> Subject: atari800xl
> Date: Thursday, June 26, 1997 10:39 AM
>
> anyone know the video pinouts so I can build a cable for this? i just
> learned it has a video output.
> >The Basic was an 4k microsoft basic with floating point and simple =
> >arrays but no alphanumeric operators or transcendental functions.
> =20
> >Tiny basic was an integer language of less than 4k. =20
>
> IIRC Level I Basic was floating point but it was not a Microsoft =
> product. Only Level II Basic came from Microsoft. In fact the source =
> for Level I Basic was later released and I think I have a copy of it in =
> storage somewhere.
I pulled my notebooks from 76/77/78 and yes RS called it Tiny but, is was
not. Tiny basic was the generic name given to ALL integer basics. At the
time the only source available basic that was floating point was LLLbasic
(lawence livermore labs) which as 8080 code fit in 5k of rom. I suspected
at the time it could be a z80 recode for space, no match.
Of the tiny basics palo alto TB (1976) was well known and fit in 2k of
rom without IO drivers. It didn't match L1.
My files indicate that the basic was most closely that of MITS altair basic
4k (pre- MS) by gates/allen. Techically is was not MS. It was at least
looking at my notebook significantly identical. That particular basic was
an early lost one and after about 79-80 its not seen in MSbasic docs. I
suspect it was due to it being pre MS and having allens hand in it. FYI
mits 4k basic was small enough to fit in 4k of ram and still hold the video
and keyboard drivers.
Allison
> Level I BASIC was _NOT_ a Microsoft BASIC. It was a fairly straight
> rendition of Tiny BASIC. Unless I've been lied to for many years. The
> Tiny BASIC published in Interface Age did have floating point, though not
> much precision.
You were lied to. ;-) I have the IA articles for TB and TBX along with DDJ
and BYTE. tiny basic was integer. There were several small basics that fit
in 4k that were not like L1 (different mix of capability) or were MS 4k
clones. Technically it was MS4k. I'd used the altair version and the TRS80
and they were Identical!
> The keybounce was a bug in the hardware. Mine always came back when I
> turned the keyboard upside down and dumped out a few months worth of
> cigarette ashes. A week later the problem would go away. (Proof that I
> didn't grow up in a clean-room computer environment -- I was 23 and out
> of the USAF when I got that Mod I in '78).
Wrong. I was doing systems design for a terminal company while at RS(i was
not in sales). That terminal company used the exact same keyboard.
Switches bounce, debounce is simple you detect closure wait a few MS and
verify closure if the verify fails the switc is open. The 4k basic didn't
wait long enough but, beniding the contacts to change their dynamics was
often enough. The verification if this is I clocked off a pulse gen and
at 1.15mhz the bounce would go away! The delay rountine was in software
so slowing the cpu was enough to make the dely longer and it would behave.
some of the speed mods made it worsse unless LII was in there.
I still have my trs80 hackboard (much modified and mangled) that I used to
test various and sundry ideas.
Of course when Tandy has launched the trs80 I'd had my altair up and running
for some time with a TTY, ct1024 (64x16 upper only) and PR40 printer for a
while.
Allison
> > modifications), and power supply brick. Level I BASIC is similar to
> > Tiny BASIC. I still have my Level I BASIC reference manual.
>
> Level I BASIC _was_ Tiny BASIC.
NO IT WAS NOT. LEVEL-I basic was the same basic sold by gates for the
altair just a later revision level. IT was little, it ws limited but to did
have floating point math and a few otehr things not found in tiny basics of
the time.
Tiny BASIC was one of several basics that
were integer math only and far more limited and generally smaller too.
Once upon a time there were three basics from MS, 4k, 8k, 12k extended,
disk (~23k), and compiled(bascom). L1 was 4k and LII was the 12k extended
with mods.
> Dennis Kitsz did once publish an upgrade to 48k that could be done in a
> keyboard without the EI. I have no idea how many others built it, but I
> never had a problem with the alleged memory speed problems from the EI
> cable. Jerry Pournelle's gripes are another story.
It was never memory speed it was ras/mux/cas timing that was marginal.
after about late 79 the design was substantually changed to derive the
signals loacally in the EI.
stacking 32k more in the keyboard was a trivial task. IF you didn't mind
staking the chips three high and skywiring the cas/ lines for the added
chips to a decoder. It did work well.
> > - RS-232 interface board > For expansion interface.
>
> Worked better than an Apple serial card from the era.
The RS card worked excellent if the connector did!
> I _still_ don't understand that trade-off between cost and utility. The
> decision makers were gone before I joined the company in '80.
INthe trs 80 case some of it was the lack of decision making by other than
marketing/sales types. I was there from 74-79 and helped launch and fix the
trs80
>
> It was more reliable than the cassette interfaces for the Apple or the Pe
> ot the Atari. _All_ cassette interfaces are unreliable. How many people
Generally speaking all audio cassette interfaces were poor. Some were
poorer than others. I'd tried digital (saturation recording) using a
modified trs80(all the analog gone) and it was absolutely reliable. The
recorder electronics were no more complicated than athe audio just
different.
> more than a few eval and review units when Tandy announced the TRS-80
> Microcomputer System on 3 Aug 77 with 5,000 units already in the
> warehouses -- idea was, since they didn't know if it would work, they had
> 5,000 stores -- if the silly things didn't move they'd figure out a way
The first year of sales exceeded 250,000!
> The one Percom used came out after the design was final.
The percom design existed at least a year before the design was started.
It was straight out of the wd1771 data sheet!
----------
From: Cord Coslor[SMTP:coslor@pscosf.peru.edu]
Reply To: classiccmp(a)u.washington.edu
Sent: Thursday, June 26, 1997 2:50 PM
To: Discussion re-collecting of classic computers
Subject: MSX, TRS-80, Colour Genie, etc.
> I am located in central Nebraska, USA, and am looking for the following to
> add to my collection. If you have these systems or might be able to get
> them for me at a reasonable price, PLEASE e-mail me.
>
> MSX computer
> Colour Genie
> TI 99/4a
I have a Colour Genie and a Sony HitBit HB75 and also a Ti99/4A
as I live in germany sending the TI99/4A makes no sense but if you
are interested in the other items drop me a note. I would like to
swap them on a "I send them to you and pay on my own and you send
me some other stuff and pay for the shipping". What do you think?
Here my URL for some other stuff I have to trade:
http://192.102.161.122/~walgen/
> > > Remember it? If it's what I am thinking of, I was doing it a couple
of
> > > weeks ago. You are talking about a 'Coconut', right (explanation of
that
> > > codename also on request - it has _nothing_ to do with the Tandy
CoCo).
> > > Nowadays I do something similar. I create a GROB with the right bit
> > > patterns, use the SystemRPL 'Get' routine to remove the header, and
thus
> > > create new objects.
No, not quite. The HP-41C used 2, 3 or 4 bytes to create the program steps.
By forcing apart the bytes and substituting new ones, new ("synthetic")
opcodes could be created.
These ranged from creating new characters to being able to access areas of
memory.
Ah, the heady days of discovery! Mother HP wouldn't officially help, but
there was plenty of behind-the-scenes help.
Hello folks!
What information is there on the CBM 900? I was mailed by someone who has
a working one and is looking for more information on the machine. Any info
would be lovely. Btw, his machine is apparently a prototype (it says so
somewhere -- probably a sticker or something).
Thanks,
Alexios
--------------------------- ,o88,o888o,,o888o. -------------------------------
Alexios Chouchoulas '88 ,88' ,88' alexios(a)vennea.demon.co.uk
The Unpronounceable One ,o88oooo88ooooo88oo, axc(a)dcs.ed.ac.uk
>>modifications), and power supply brick. Level I BASIC is similar to
>> Tiny BASIC. I still have my Level I BASIC reference manual.
>The Basic was an 4k microsoft basic with floating point and simple >arrays but no alphanumeric operators or transcendental functions.
>Tiny basic was an integer language of less than 4k.
IIRC Level I Basic was floating point but it was not a Microsoft product. Only Level II Basic came from Microsoft. In fact the source for Level I Basic was later released and I think I have a copy of it in storage somewhere.
Regards,
Bob
Kai Kaltenbach <kaikal(a)MICROSOFT.com> writes:
> Other Upgrades:
You left out the TRS-80 Screen Printer, a widget that plugs into the
connector otherwise used for the Expansion Interface. Hit the switch
on the front of the printer, and it ejects a few inches of silvery
electrostatic paper with the image on your screen zapped dark on it.
My understanding is that it grabs the image right out of the screen
memory.
Somewhere I have some pages printed by one of these. As I recall they
didn't last long as a product. I think I have two Radio Shack
microcomputer catalogs from 1978 (one white/black/silver, one later
one in full color) and the screen printer is only shown in the earlier
catalog, but both are loaned out to someone who wanted to scan some
pictures from them. (Hey Javier, are you reading this?)
-Frank McConnell
Sorry, I for got to aadd these to my last message. Also found some
software. I've never used this stuff so it's an as-is deal.
Geos Lot:
Looks like a set of GEOS 2.0 and 1.2
Manuals for 1.2 and 2.0
Deskpak Plus (six applications for GEOS)
Deskpak Manual
25 Blank 5-1/4 disks
Price $5, Shipping $2.75
C-64 Game/Software Lot:
Zork I or C64 with Manual
Flight Simulator II in box w/manual
AwardWare Graphics
Starcross game w/manual
Business
Indoor Sports w/manual
Into the Eagles Nest (WWII)
Box of 12 misc disks w/some s/w
Price $5, Shipping $2.75
I'm sorting through the boxes of "stuff" I have accumulated and I've
saved a pile of books you folks might be interested in. I am selling
them in lots because I don't have time to pack up and mail them out
individually. Besides they're going cheap! Shipping via USPS Book Rate.
Commodore Lot:
The Manager - Commodore 64
C64 User's Manual
Kids and the Commodore 64
Commodore 64 Favorite Programs Explained
Re Run - Reprinted Articles from Jan to June 1984 - Run Magazine
VIC 1541 User's Maanual
More than 32 Basic Programs for the C64
Commodore 64 User's Handbook
Commodore 64 Programmer's Reference Guide
Turte Graphics II Instruction Manual
Price $5, Shipping $4.25
Apple Lot:
Critic's Guide to Software for Apple and Compatible Computers
Apple II Super Serial Card Manual
Apple II 80-Column Text Card Manual
Extended 80-Column Text Card Supplement
Apple II The DOS Manual
Applesoft II Basic Programming Reference Manual
Price $5, Shipping $4.25
Other Lot:
10 Starter Programs from Family Computing (Apple, Atari, etc, 1983)
1986 Radio Shack Software Reference and Tandy Computer Guide
A Bit of Basic (Apple II, TRS-80)
Price $2.75, Shipping $2.25
The Model I originally shipped without a numeric keypad. To the right
of the main keyboard was a rectangular keypad-size plaque reading "Radio
Shack TRS-80 Micro Computer System". The numeric keypad was added to
later models, and was available as a retrofit kit for around $50. With
the numeric keypad installed, the nameplate was moved to a horizontal
plaque above the keyboard.
The TRS-80 Model I lineage includes:
Model I, 4K, Level I BASIC
- This is a 3-piece system with the computer in the keyboard. It
includes the system keyboard/cpu, monitor, tape drive (actually a
rebadged regular Radio Shack portable cassette deck with no
modifications), and power supply brick. Level I BASIC is similar to
Tiny BASIC. I still have my Level I BASIC reference manual.
Model I, 16K, Level II BASIC
- The 16K and Level II upgrades went together. 16K is the maximum Model
I memory in the system unit (8x 4116 DRAMs). Level II BASIC is similar
to Microsoft BASIC/80 with functions added for things like the TRS-80's
128x48 memory-mapped monochrome graphics. Level II also added a
keyboard debounce routine--Level I machines were very difficult for
typists.
Other Upgrades:
- Expansion Interface
Matching silver color, acts as a monitor stand, connects to system unit
via ribbon cable. Contains dual floppy controller (WD chip), sockets
for an additional 32K (2 banks of 4116 DRAMs) for a system maximum of
48K, and a parallel connection. 16K ROM BASIC occupied the remainder of
the address space. The expansion interface also contains a card bay for
an RS-232 interface.
- RS-232 interface board
For expansion interface.
- Floppy drives
Single-sided single-density, approx. 90KB free space.
- Lower case upgrade
Provides lower case capability.
- Numeric keypad retrofit
As discussed above
Known TRS-80 Model I problems:
- Unreliable cassette interface. Radio Shack later released a
modification that improved this somewhat. The best option is a
third-party unit called the Data Dubber by Microperipheral Corporation
(I worked there!) that went in between the system unit and cassette and
squared the wave.
- Wonky, unbuffered connection to Expansion Interface. This went
through various modifications, and some cables you'll see have big
buffer boxes in the middle. Later Expansion Interfaces had built-in
buffering. Some bought third-party expansion interface clones from Lobo
and others. Be very careful if you get an Expansion Interface without a
cable. It might need the buffered cable, and it would be a pain to
manufacture.
- Bad data separator chip. The stock data separator was unreliable.
Most people replaced theirs with a third-party improvement such as
Percom's.
- Unreliable connection for the Expansion Interface-mounted RS-232
board. This board slipped over vertical post connections and never made
good contact. Most folks used third-party alternatives that worked off
the cassette port.
Kai
> ----------
> From: Mr. Self Destruct
> Reply To: classiccmp(a)u.washington.edu
> Sent: Wednesday, June 25, 1997 4:14 PM
> To: Discussion re-collecting of classic computers
> Subject: Re: MSX, TRS-80, Colour Genie, etc.
>
>
> On Wed, 25 Jun 1997, Scott Walde wrote:
>
> > No. They were originally known (and labelled) as the TRS-80
> Microcomputer
> > System. They later became known as the model 1 (Although I don't
> think
> > they were ever labelled as such.)
> >
>
> Were there two different Model 1's? I have seen pictures of Model 1's
> that don't look like my Model 1. (i.e. no numeric keypad)
>
> Les
> more(a)crazy.rutgers.edu
>
>
>
>> Compressed 1-bit, 300 dpi TIFF for schematics
>> - Almost everything supports TIFF, including tons of shareware and
[technical stuff snipped]
>I'm not so sure that "everything" supports TIFF. After a little looking,
>I couldn't even find a TIFF file to test with xv.
Is there anything for either OpenVMS/Alpha (No DEC/X-windows) or the
Apple IIGS that can read TIFF?
>> RTF (Rich Text Format) for text documents that use formatting
>> - WordPerfect, Word, WordPad, etc. will save in this format
How about HTML? That would likely be more readable for my shell
account (though not all formatting would be displayed in Lynx).
I suppose I could walk over to the computer lab and use a Mac or a PC
if I *had* to. :)
--
Andy Brobston brobstona(a)wartburg.edu ***NEW URL BELOW***
http://www.wartburg.edu/people/docs/personalPages/BrobstonA/home.html
My opinions do not necessarily reflect the opinions of Wartburg College
as a whole.
Hey, figuring out standards like this is what I do. I recommend:
JPEG for photo scans (brochures, ads, etc.)
- It's the Internet photo file format standard
Compressed 1-bit, 300 dpi TIFF for schematics
- Almost everything supports TIFF, including tons of shareware and
Wang's free image processing add-on for Win95
(http://www.microsoft.com/windows95/info/wang.htm)
- 1-bit means monochrome (not grayscale). Use JPEG for images.
- Images should be 300 dpi, 8 1/2" x 11", i.e. 2550 x 3300 (don't worry
about scanning white space, it takes no space at all when compressed)
TXT for text documents that don't use formatting
- 80-column with carriage returns please
RTF (Rich Text Format) for text documents that use formatting
- WordPerfect, Word, WordPad, etc. will save in this format
Kai
> ----------
> From: Bill Whitson
> Reply To: classiccmp(a)u.washington.edu
> Sent: Wednesday, June 25, 1997 1:05 PM
> To: Discussion re-collecting of classic computers
> Subject: Archiving Stuff
>
> Hi all.
>
> Consider Classiccmp Web/FTP open for your archiving pleasure ;).
>
> The process has been more or less tested out and is ready to go.
> Submissions of Software, Documentation, ROM code, whatever are all
> OK.
>
> What really remains to be done is to work out standards for file
> formats. I'll let those of you who are experts on specific platforms
> argue that out. I'll follow whatever ensues and firm up some
> guidelines.
>
> To submit something you need to download the form DS-form.txt from
> the FTP site (140.142.225.27) and fill it out to the best of your
> ability. Follow the instructions at the bottom of the form for
> uploading.
>
> All the form does is provide evidence (if anyone ever complains) that
> I'm not just uploading copyrighted material without a care.
>
> Anyway - if you're itching to archive stuff feel free. Your comments
> are welcome and also unavoidable ;)
>
> Bill
>
> ----------------------------------------------------
> Bill Whitson - Classic Computers ListOp
> bill(a)booster.u.washinton.edu or bcw(a)u.washington.edu
> http://weber.u.washington.edu/~bcw
>
>
> The Model I originally shipped without a numeric keypad. To the right
Correct.
> of the main keyboard was a rectangular keypad-size plaque reading "Radio
> Shack TRS-80 Micro Computer System". The numeric keypad was added to
> later models, and was available as a retrofit kit for around $50. With
> the numeric keypad installed, the nameplate was moved to a horizontal
> plaque above the keyboard.
Also correct.
>
> The TRS-80 Model I lineage includes:
>
> Model I, 4K, Level I BASIC
> - This is a 3-piece system with the computer in the keyboard. It
> includes the system keyboard/cpu, monitor, tape drive (actually a
> rebadged regular Radio Shack portable cassette deck with no
> modifications), and power supply brick. Level I BASIC is similar to
> Tiny BASIC. I still have my Level I BASIC reference manual.
The Basic was an 4k microsoft basic with floating point and simple arrays
but no alphanumeric operators or transcendental functions.
Tiny basic was an integer language of less than 4k.
> Model I, 16K, Level II BASIC
> - The 16K and Level II upgrades went together. 16K is the maximum Model
> I memory in the system unit (8x 4116 DRAMs). Level II BASIC is similar
wrong. Either could be installed alone. Generally LII with 4k was pretty
cramped. FYI: the LII romset was only 12k.
> to Microsoft BASIC/80 with functions added for things like the TRS-80's
> 128x48 memory-mapped monochrome graphics.
It was MS12k basic with TRS extensions (graphics).
>Level II also added a
> keyboard debounce routine--Level I machines were very difficult for
> typists.
The key bounce was a bug in the original 4k software, it didn't wait long
enough. There was a cassette that when loaded fixed it. Me I'd clean the
key contacts with a swab and some contact cleaner and get the same result.
> - Expansion Interface
> Matching silver color, acts as a monitor stand, connects to system unit
> via ribbon cable. Contains dual floppy controller (WD chip), sockets
> for an additional 32K (2 banks of 4116 DRAMs) for a system maximum of
> 48K, and a parallel connection. 16K ROM BASIC occupied the remainder of
> the address space. The expansion interface also contains a card bay for
> an RS-232 interface.
The bottom 16k was 12k of rom (LII basic) 1k of ram for video and keyboard
mapped in to memory space. Some of the 4k space for the video and keyboard
was wasted due to partial decode. The upside was since the keyboard was
scanned by the cpu so alternate shift and character sets were easy to do.
The down side is no matter how you tried, keyboard type ahead was
impossible, the keyboard could not interrupt the CPU.
> - RS-232 interface board
> For expansion interface.
The surface connector used was very cranky.
> - Floppy drives
> Single-sided single-density, approx. 90KB free space.
The design used the 1771 internal data seperator which was not very tolerent
of drive spped errors or data jitter.
> - Lower case upgrade
> Provides lower case capability.
Way late in the game the "field mod" had been around over a year before
tandy did it.
> - Numeric keypad retrofit
> As discussed above
Popular item!
> Known TRS-80 Model I problems:
>
> - Unreliable cassette interface. Radio Shack later released a
> modification that improved this somewhat. The best option is a
> third-party unit called the Data Dubber by Microperipheral Corporation
> (I worked there!) that went in between the system unit and cassette and
> squared the wave.
There were two mods one largely marginal, the later one was very effective.
I had a mod I did that worked very well and was far simpler.
> - Wonky, unbuffered connection to Expansion Interface. This went
> through various modifications, and some cables you'll see have big
> buffer boxes in the middle. Later Expansion Interfaces had built-in
> buffering. Some bought third-party expansion interface clones from Lobo
> and others. Be very careful if you get an Expansion Interface without a
> cable. It might need the buffered cable, and it would be a pain to
> manufacture.
The first version with the unbuffered or buffered cable was a junk design.
the later one with local ras/cas timing was far better.
> - Bad data separator chip. The stock data separator was unreliable.
> Most people replaced theirs with a third-party improvement such as
> Percom's.
The stock circuit depended on the 1771 chips internal seperator, Even WD
the chipmaker said don't do it!
> - Unreliable connection for the Expansion Interface-mounted RS-232
> board. This board slipped over vertical post connections and never made
> good contact. Most folks used third-party alternatives that worked off
> the cassette port.
Being there at the begining was half the fun.
Allison
> > really think the engineers blew it. The original OS is too innovative,
> > so much that the computer is nearly unuseable.
>
> I wouldn't think that "too innovative" would result in a lesser rating fo
> "technical" aspects (at least in the realm of computer history/collecting
> the "real" world is a different matter (see "success"...))
Lest we forget the LISA was the Prototype system for the mac!
Allison
> I am looking for
>
> IBM PC Junior
> Apple II
> TRS-80 (model I)
I think I have a couple of trash-80's in the back room. One with disks, one
without. Do they say "model 1"? (I don't know these at all)
Does have a Lisa he/she wants to unload?
I also have several, nice-condition Commodore boxes that I'd hate to pitch.
As long as we're in the subject of trading, I have several years of PPC (HP
programmable calculator user group) that I'd *love* to find a home for
of...absolutely fascinating stuff, including the origin of Ulam's
conjecture.
