21 Nov
1998
21 Nov
'98
8:18 p.m.
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/
22 Nov
22 Nov
2:25 a.m.
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23 Nov
23 Nov
1:06 a.m.
Cameron,
What type of computer is this for? I have two chicklet style keyboards for
the IBM PCjr.
John Amirault
Cameron Kaiser wrote:
::The life of a chicklet-keyboard PET may depend on
this. :)
Which model is that?
--
-------------------------- personal page: http://calvin.ptloma.edu/~spectre/ --
Cameron Kaiser Information Technology Services Database Programmer
Point Loma Nazarene University Fax: +1 619 849 2581
ckaiser(a)ptloma.edu Phone: +1 619 849 2539
-- FORTUNE: Good day for romance, but try a single person this time. ----------
2:50 a.m.
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28 Nov
28 Nov
11:28 a.m.
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.
"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.
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
3:04 p.m.
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5 Dec
5 Dec
11:45 p.m.
New subject: PET keyboard (was: Re: Replacing 6550s)
On Sat, 28 Nov 1998, Cameron Kaiser wrote:
::"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?
It's not the keys themselves (they're made of white plastic) but the
square inserts on top of them that are coloured.
Red, dark blue, pale blue, grey.
The SHIFT keys, SPACE, RETURN, CLR/HOME, and INST/DEL are red with white
letters.
OFF/RVS, RUN/STOP, and the to CRSR keys are dark blue with white
lettering.
All of the letters, the numbers, ':', and '.' are grey with black
lettering.
All else is pale blue with black lettering.
The blues and grey are somewhat metallic in appearance.
A very funky keyboard.
--
-------------------------- personal page: http://calvin.ptloma.edu/~spectre/ --
Cameron Kaiser Information Technology Services Database Programmer
Point Loma Nazarene University Fax: +1 619 849 2581
ckaiser(a)ptloma.edu Phone: +1 619 849 2539
-- When in doubt, take a pawn. -- Mission: Impossible ("Crack-Up") ------------
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
22 Nov
22 Nov
5:52 a.m.
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28 Nov
28 Nov
8:22 a.m.
Hi Tony!
On Sun, 22 Nov 1998, Tony Duell wrote:
Link up corresponding pins. You can ignore supply
lines other than +5V
and ground. If the new ram has extra address lines, tie them low. If it
has extra data lines, then pull them high through a 1K (or 10K, or just
about anything) resistor.
Please forgive my ignorance, but when you say to 'tie low' or 'pull
high',
that means 0V and +5V respectively? Is tying low the same as attaching to
ground?
I want to be able to do this kind of project, but I don't even know the
basics. :/
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
11:12 a.m.
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22 Nov
22 Nov
5:53 a.m.
Doug Spence <ds_spenc(a)alcor.concordia.ca> wrote:
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.
I haven't seen the PET schematics, but since the 6550 had multiple chip selects
it might be necessary to wire up a decoder as well as a RAM chip.
3:09 p.m.
Hi all!
Thanks to everyone who supplied information regarding the differences
between the 6550 and 2114 (especially Ethan who supplied pinouts).
You're welcome.
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.
Sure thing.
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.
There is that big edge connector on the side of the static PETs (it was
two seperate pin connectors on later PETs). All the signals you need for
RAM expansion are there. For maximum preservation, I'd consider pulling
all the 6550's out of the board and sticking them in a bag. Then, wire
up a 6264 (or 62256!) to a small board after finding a suitable connector.
I expect the pinout to be on ftp.funet.fi, but if it isn't, I can dig
out my PET schematics. If I still had my old 4K PET, I'd build one, too.
You shouldn't have to build a clip-on, but if you did, there's nothing
to keep it from working. You can get all the data bits from two sockets,
and all the address bits from one socket, plus the additional bits
from somewhere else. Remember that part of the logic
in the PETs decodes
the A8-A11 lines to chip selects. You need the original address
bits,
not the decoded ones.
-ethan
28 Nov
28 Nov
11:07 a.m.
On Mon, 23 Nov 1998, Ethan Dicks wrote:
There is that big edge connector on the side of the
static PETs (it was
two seperate pin connectors on later PETs). All the signals you need for
RAM expansion are there.
Yup, you're right. I didn't look at the pinout for that before posting,
I just assumed that I wouldn't be able to access the first 8K of addresses
from there, because it would conflict with the chips on
the motherboard.
There are 12 address lines and 10 select lines.
It would be aesthetically preferable to mount this thing internally via
the chip sockets, but with the edge connector I could expand the PET's RAM
to the max. And it would sure beat that hideously huge 16K RAM expansion
via the PET-to-S100 bus adapter, with its own huge power supply. :)
For maximum preservation, I'd consider pulling all
the 6550's out of the
board and sticking them in a bag. Then, wire up a 6264 (or 62256!) to a
small board after finding a suitable connector. I expect the pinout to
be on ftp.funet.fi, but if it isn't, I can dig out my PET schematics.
If I still had my old 4K PET, I'd build one, too.
I've got the pinout in my "An Introduction To Your New PET Personal
Electronic Transactor" manual. :) According to the bottom of page 23 of
this booklet (I'm going to try to reproduce it as closely as possible
here, for the fun of it):
=========================================================================
MEMORY EXPANSION
40 positions, 80 contacts edge card connector with .1" spacing. No keys.
Top side at connector (B1-40) is grounded.
___
A1 A0 A11 A10 A21 SEL 6 A31 NC | TYPICAL
___ | CONNECTOR
A2 A1 A12 A11 A22 SEL 7 A32 NC |
___ | Sylvania
A3 A2 A13 NC A23 SEL 9 A33 BD0 | 6AD0-40-1A1-01
___ |
A4 A3 A14 NC A24 SEL A A34 BD1 | Viking
___ | 3KH40/1JN5
A5 A4 A15 NC A25 SEL B A35 BD2 | 3KH40/9JN5
___ |
A6 A5 A16 SEL 1 A26 NC A36 BD3 | Sullins
___ ___ | ESC-40-DREH
A7 A6 A17 SEL 2 A27 RES A37 BD4 |
___ ___ | Cinch
A8 A7 A18 SEL 3 A28 IRQ A38 BD5 | 251-40-30-410
___ ___ |
A9 A8 A19 SEL 4 A29 B02 A39 BD6 |
___ ___ |
A10 A9 A20 SEL 5 A30 R/W A40 BD7 |
___
Address selects are decoded in 4K blocks, i.e., SEL 1 selects $1000-1FFF,
___
SEL B selects $B000-BFFF.
=========================================================================
(I especially find it cool that they list various part numbers for the
connector. :) )
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?
You shouldn't have to build a clip-on, but if you
did, there's nothing
to keep it from working.
How would I select memory block 0 without plugging into the motherboard
somewhere?
You can get all the data bits from two sockets, and
all the address bits
from one socket, plus the additional bits from somewhere else. Remember
that part of the logic in the PETs decodes the A8-A11 lines to chip
selects. You need the original address bits, not the decoded ones.
I guess it would be better (easier) to use the edge connector.
-ethan
--
Doug Spence
ds_spenc(a)alcor.concordia.ca
http://alcor.concordia.ca/~ds_spenc/
11:46 a.m.
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9296
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9310
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13 comments
6 participants
participants (6)
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amirault＠epix.net -
ard＠p850ug1.demon.co.uk -
ckaiser＠oa.ptloma.edu -
ds_spenc＠alcor.concordia.ca -
erd＠infinet.com -
eric＠brouhaha.com