Doug Spence wrote:
>> The original PET came with four different motherboard variations, viz:
>>
>> RAM = 6550, ROM = 6540
>
> Both of my PETs are of this type, but one has the small keyboard and
> internal tape drive, and the other has the big keyboard.
Large keyboard on a machine that early is a new one on me!
>> My own is the third of those, a 1978 revision (a pity in a way - the
case
>> has the old tape deck, the blue screen surround and serial number
1000035,
>> one of the very first)
>
> Are you sure that 1000035 makes it one of the first? Perhaps it's one of
> the first of that revision or something?
Blue trim was dropped fairly early - both the machines we had at school
were black trim - as was the rebadged cassette deck with the lift-the-lid
eject mechanism, the latter being replaced by the C2N. I had always
assummed that 1000035 meant the 35th machine with the 220-240V power
supply.
> My PETs are 0014090 (small keyboard) and 0020272 (large keyboard). Both
> have the first motherboard variation, blue trim, and white screen.
Help. We need the Anderson. Larry, where are you? Can you help on this?
> Actually, IIRC my small-keyboard PET uses little rubber cups. But I
> suppose there may be springs as well. The keyboard didn't work when I
got
> it, so I had to disassemble it and wipe the circuit board clean. I never
> disassembled it beyond pulling the circuit board off.
No rubber cups. Rubber cups or domes always in my experience give some
sort of mechanical hysteresis when you press them. All PET keyboards I've
used are smooth until they hit the stop. Small keyboard had little black
rubber pads set into the plastic mouldings of the keys.
>> The top 4 address lines are decoded on the mobo by a 74154 to give block
>> select lines. The block select lines 0 (bottom 4K of RAM), 8 (screen
>> memory) C, D, E (I think) and F do _not_ appear on the expansion
connector.
>> All others do. The rest of the address lines (0 to 11) are also
present.
>
> Yup, you're right. Interestingly, Blocks 9, A, and B are listed as
> "Expansion ROM" on my PET memory map... I had a dream a while back where
> the university was throwing all kinds of neat old junk out, and I found a
> horde of PET cartridges(!) that plugged into the side expansion port.
> While I've never heard of such a thing, is there any reason a cartridge
of
> that type couldn't have been a reality?
Only the lack of power. Flying lead from cartridge to 2nd cassette port is
the usual solution AFAIK (it's what I did on my RAM expansion). No, I've
never heard of ROM cartridges like this but I've met other things I think.
ROM expansion usually went inside...
>> When I added a 62256 to my 8K PET, I encoded the block select lines for
24K
>> of RAM space and 8K of expansion ROM space (blocks 9 and A). Beware -
POKE
>> also fails here, not just PEEK, if you're accessing this RAM from BASIC.
>
> So you've actually already done something like this! Excellent!
Indeed I have. Tony Duell helped with one or two tips, I think. Such as,
65256 doesn't work, use 62256 instead. And the way of avoiding the need
for inverters if you use the right sort of gate when re-encoding your
address (but I may have failed to implement that).
> Why do POKE and PEEK fail there? Was that done on purpose or is it just
> the result of something lame like using a signed value to represent
> addresses?
No, it's software. It was a feature that was supposed to prevent
inquisitive geeks disassembling the BASIC ROM between $C000 and (I think)
$E7FF. The OS ROMs, above $F000, were peekable, though, as was the I/O
space in the E block. You could of course peek and poke the screen, $8000
- $83E7 inclusive.
> I think *all* of the 6550s in that machine are duds, but I could move 4K
> over from the working machine. (I've tried the dead ones in many, many
> combinations but perhaps not all.)
Zog! You'll have to pull block select 0 from somewhere on the motherboard
then. You might as well take +5V from there while you're at it.
I'll try and dig out my RAM expansion board, and work out what it did.
Meanwhile, have fun!
Philip.
> From: Doug Spence <ds_spenc(a)alcor.concordia.ca>
> Subject: Re: Replacing 6550s
> (I especially find it cool that they list various part numbers for the
> connector. :) )
Digikey is the best source for inexpensive PET compatible connectors.
(1-800-DIGI-KEY) along with a ton of other cool parts.
>
> I just noticed for the first time (!) that the "PARALLEL USER PORT" has
> pins labeled "T.V. Video", "T.V. Vertical", and "T.V. Horizontal"! Has
> anyone actually connectd a TV or external monitor to a PET?
There are plans for a composite video converter using those pins in Nick
Hampshire's PET Revealed, I think it only works on the older 9" screen pets
and not the 12" ones. The reason for it being on the user port was for deaier
diagnostic testing.
I'll scan the circuit and put it on-line tonite:
http://www.goldrush.com/~foxnhare/petvideo.gif
0010010101011100101001010001010010101000101001010
> On Mon, 23 Nov 1998, Cameron Kaiser wrote:
>
> > I'm trying to find out what PET has a chiclet keyboard. I only know of the
> > plastic bang-on-em keyboard PETs, not one with the rubber keys.
>
> There aren't any with rubber keys as far as I'm aware.
The 'rubber part of the keys is on the boom of the key, which you don't see.
The only Commodore computer with rubber keys that I have heard of is the
Commodore 116.
>
> "chiclet keyboard" != "rubber keys", IMHO. I'm talking about the cute
> multicoloured keyboard with the small plastic keys that are arranged in a
> grid pattern. I call that a chiclet keyboard.
The original PET 2001 (4k or 8k), and I saw a 'Teacher's PET' with such a
keyboard too (proably had a newer motherboard though. In general they
(calculator keyboard model PETs) were sold till about 1980 and are the
origninal keyboard design.
0010010101011100101001010001010010101000101001010
> ::"chiclet keyboard" != "rubber keys", IMHO. I'm talking about the cute
> ::multicoloured keyboard with the small plastic keys that are arranged in a
> ::grid pattern. I call that a chiclet keyboard.
>
> Hmm, okay. But multicoloured? Which colours? Arranged how?
Ummm they were all metallic tops, Red, Gold, Blue, Silver... Check out my
PET page:
http://www.goldrush.com/~foxnhare/pet.html
You can see the colors pretty well on the first image.
If you want exact placement I'll scan a keyboard layout from the PET user
guide tonite:
http://www.goldrush.com/~foxnhare/petkeys.gif
0010010101011100101001010001010010101000101001010
> From: Cameron Kaiser <ckaiser(a)oa.ptloma.edu>
> Subject: Re: Commodore 128 stuff (was:St. Vincent DePaul Finds)
>
> ::It's a fast-loader for the 128 (that's where the Mach comes in , the 64
> ::version was called Mach 5) It might also be a program freezer/utility. Put it
> ::in your 128 and push the reset button, some of these will present a menu (for
> ::save options and such). The switch is probably to select whether the cart is
> ::active or not. Best not to switch it while the computer is on.
>
> Gosh, Larry, don't you want to live dangerously? Switching EXROM and GAME
> in realtime? Live a little! ;-)
After a few Commodore (PET, 64, 128D and Amiga 1000) mishaps between me, my
brother and a couple friends, I have become much more careful. I do not want
to be the holder of the 'golden butterknife' (yeah, that one went over your
head, it's a long story.)
Hi all!
Thanks to everyone who supplied information regarding the differences
between the 6550 and 2114 (especially Ethan who supplied pinouts).
I'm wondering if it would be possible to replace the RAM in an old PET
with a modern SRAM by use of some kind of plug-in adapter.
An example of what I'm thinking of is the SIMMfonie or AmiFast Zip-to-SIMM
adapters for the Amiga 3000. Could something like this be built that
would plug into the 16 22-pin sockets on the PET motherboard, and lead to
a single modern SRAM? Possibly with the addition of a couple of clip-on
leads to get two more address lines to the RAM adapter so that the PET
could have 32K.
My general preference is to keep things original, but functional is always
better than non-functional and something like this adapter would be
removable if I ever found the proper chips.
The life of a chicklet-keyboard PET may depend on this. :)
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
Classic Computer People!
Since I think this stuff is neat, I will only send this to
ClassicCmp and Port-Vax lists.
I need to get rid of this stuff. I will take bids on this
stuff until Friday(12/4/98). If this stuff does not sell
by Friday, I'll try to sell it at the swap meet Saturday ;-)
Buyer assumes the shipping costs from Las Vegas, Nevada, USA.
Thanks
Dean Nelson
Assemble my addresses from the lines below
For any Questions during the day:
Dean dot Nelson
at
LMCO
dot
COM
To send a bid or questions:
DeanNelson
at
AOL
dot
Com
(Yes, I get tons of crap mail, so please mention something sane
in the subject ;-) )
-------------------------------------
MICRO VAXES
-----------
VaxStation 3100 M76, 32MB Ram (Model VS43A-CY)
CPU: KA43-A
Disks: RZ23-E (104MB), RX23-AA(floppy)
OS: None, main boot disk was removed, still has the RZ23
Weight: 25 lbs
Vax Server 3100, 16MB Ram (Model DJ-31ESA-A-A01)
CPU: KA41-E
Disks: RZ24 (209MB)
Tape: TZ30
OS: VMS 5.5-2, No License
Weight: 36 Lbs
MicroVax 3100-40, 16MB Ram ( Model 450ZM-B9-A01)
CPU:KA45-A
Disks: RZ25 (426MB)
Tape: TZ30
OS: VMS 5.5-2 (No License)
Weight: 38 lbs
-------------------------
MONITORS
--------
Two of these:
DEC 19" Monitor - Model VR299-DA
Weight: 75 lbs
One - Data General 17" Monitor Trinitron
Model - GDM-1601 (RGB+H+V)
-------------------------
KEYBOARDS
---------
Eight of these:
DEC LK201 keyboards
I haven't tried out any of these.
---------------------------
DG AVIIONs
----------
Two of these:
Data General Aviion Model AV 410
CPU: Dual 88K, 20Mhz processors
Memory: 64mb
Disks: 1Gb SCSI, CDROM, Floppy
Graphics: 8 plane RGB
OS: DG/UX (no license)
Weight: 65 lbs
One of these boots to DG/UX the other one boots to a hardware
prompt which I assume is trying to boot from the Net
---------------------------------------------------------------
FREE STUFF (you just pay the shipping)
Dont know if any of this works.
---------------
Core Intl Hard Drive
Model: AT72 (72MB, AT Hard drive type 105)
I think this is an MFM style drive
Two of these:
19" rack mount hard drive enclosures with power supplies
One of these:
Desktop hard drive chassis for two+ full height drives.
Some other communication stuff:
two V.35 comm hub (I think thats what it is)
19" Modem rack with 8 modems (2400 baud)
harrumph; typical clueless non-computer type that thinks any old computer is
worth plenty. there's a guy at an established flea market that tries to get
the same price out of old machines. i bought a northgate 386/20 from a guy at
work and even got the great northgate keyboard too for only $20!
heh, you oughta go back to the guy and ask him if he'd be willing to buy
comparable 386 and 486 models for half his asking price. i could find some
pretty cheap machines and make profit off him!
In a message dated 11/21/98 8:25:08 PM US Eastern Standard Time,
transit(a)primenet.com writes:
> They had a no-name 386 clone, complete with color monitor, in working
> condition for $175, and a 486, no monitor, unknown condition (most likely
> working though) for $250.
>
> Seemed very high to me, as I've picked up working 8080 PC's and XT's for
> under $20. . .
>
> (They did also have an old Mac 128, but I didn't inquire about it, as
> those are not exactly rare either)
>
Ethan Dicks said:
>I am cranking along with the capture of the Elf99 design ....
I just found this thread. This is a great idea and should have been
tried sooner. I'll buy one.
>Did I miss anything? Any other suggestions?
The only thing I see missing is the expansion bus connector.
(Did I miss that part?)
There are hundreds of things that would be nice to have, but it's
important that the design be finished and the boards made. Leave the
bells and whistles to the end users. If you create an Elf that can
address about 2K, has a small prototype area, and has a good
expansion bus, then all things are possible. (Including S-100 interface)
You should copy one of the two Super Elf buses.
> A protoyping area of .1" spaced plated-through holes, nominally
> a few inches long by one or two inches wide.
A prototype area should be for wirewrapping. I don't see any need
for plated-through holes, and pads are not REALLY necessary either.
>I will not be including space
>for an 1861 because I have been entirely unable to locate a source.
The 1861 should be easy to add on later. In the prototype area or hot melted
to the top of another chip. Just make sure it's easy to cut the trace for the
original clock circuit and wire in the new one.
>Ooh. What a concept. I know there is a CHIP-8 emulator page out there.
>Perhaps there is a source version of the interpreter floating around.
I think there is a source code listing in Paul Moews book on
Elf interpreters.
=========================================
Doug Coward
Press Start Inc.
Sunnyvale,CA
=========================================
The key to the elf design was minimalism and low cost.
Substituting a latch and LEDs for a binary display instead of the til311
is cheaper and more buildable.
using modern cmos and rams help.
The basic elf was far to minimal and frequently expanded to get desired
functions. The basic design did not easily permit that as it didn't
decode memory or IO addresses.
The RCA VIP or the 18S020 Evaluation board allowed far more flexibility
with relatively little more logic. Thei cost was they had some rom.
The 18S020 board was 4k ram (1822s), two 1852 as parallel io ports, UT4
monitor rom (512bytes) and another 32bytes for monitor storage. It used
Q and EF3 for TTY/RS232 and the bus was available with numerous decodes
at the edge connector. It also had LEDs for data, address and processor
status lines (binary).
This is a reproducable design. UT4 fits in 512byts of a 2716, the rest of
the ram can be done with byte wide parts. The 1852s can be kept and the
rest were common 40xx series. With 4k of ram and UT4 (or similar)
programs like PILOT, TinyBasic, or some of the other neat software with a
terminal.
A much simplifed machine using 1802, 2 1852, 2 4028, 2 4042, 1 62256,
1 2716 and 1 6116, some glue logic for reset, run, runp and the same
serial scheme as 18S020 would give 32k of contigious ram, 2k-32byts in the
>8000h area and the remaining 1.5k in the 2716 could hold any number of
things along with the .5k ut4 monitor. This would be a very useful
system that could accomodate expansion for IO (more ram??????).
Allison
Hi!
Anyone have a hard drive controller for a Tandy 1400HD laptop that they'd
want to sell? The one in mind recently died, and when I turn it on, all I
get is a blue screen. I disconnect the HD, it starts to boot (BIOS number
comes up), then stops, and starts emitting a fish-like smell. I pull the
controller entirely, and it works fine (with no fish smell).
Any suggestions (other than getting one from RadioShack)?
ThAnX,
--
-Jason Willgruber
(roblwill(a)usaor.net)
ICQ#: 1730318
<http://members.tripod.com/general_1>
>IIRC, it's actaully a PDP-11 and the OS is a munged version of RT-11.
The filesystem it uses on TU58's is the same as RT-11's filesystem.
That doesn't mean it's running RT-11 :-). A VAX-11/780
has an LSI-11 as the console processor, it uses the RT-11 filesystem
on the boot floppies, and that doesn't mean it's running RT-11 :-).
On the other hand, VAX 8600 series CPU's use a PRO 380 console
running an operating system that *is* derived from RT-11. (The
VENUS conditionals still abound in the RT-11 sources, even
though AFAIK a build hasn't been done in over a decade.)
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
