Does anyone here remember the patches necessary to run the various versions of
Altair BASIC (4K, 8K and Extended - ver 4.0 and later) on a Z-80? They involve
the Status byte after certain arithmetic operations. When I replace my 8080A CPU
card with a Z-80 card, I can't assign a value to single precision variables. Ex:

You type: A=5:PRINT A

Altair prints 0, should print 5

You type FOR I=1 TO 10:PRINT I;:NEXT I

Altair prints

0  0  0  0  0  0  0  0  0  ....

Loop never ends since I is never incremented.

Please help!  TIA

Tom L

| From: toml_12953 <tlake@...>
|
| Does anyone here remember the patches necessary to run the various
| versions of Altair BASIC (4K, 8K and Extended - ver 4.0 and later) on a
| Z-80? They involve the Status byte after certain arithmetic operations.
| When I replace my 8080A CPU card with a Z-80 card, I can't assign a
| value to single precision variables. Ex:

I don't have it at hand.

The theory is explained in:
<ftp://computer-refuge.org/bitsavers/1401/simh_v2.9/AltairZ80/altairZ80.txt>

The 8080 has a status bit for "parity" of the last thing that went
through the ALU.

The Z80 uses the same status bit for "overflow" for arithmetic
instructions and parity for logical instruction.

Gates (or Allen) probably saved an instruction by using the parity status
after an arithmetic instruction.

(This is from my non-parity-checked memory, so it could be wrong.)

I imagine that a day of work would be all it would take to rediscover
the fix.

Being lazy, I'd instrument SIMH to find where execution diverged under
the two processors.  Or I'd just scan for opcode JPO, JPE, CPO, CPE,
RPO, or RPE in the code.  The first two are way more likely than the
others.

There seem to be two JPO instructions in this code:
<http://www.interact-sw.co.uk/altair/math_dis_10.htm>

These are involved with printing numbers.  So they might explain the wrong
number being printed but they don't explain the for loop not terminating.

They both involve testing the result of FCompare.  The Z80 and 8080 might
set the parity/overflow bit differently on the paths through SignToInt.
<http://www.interact-sw.co.uk/altair/math_dis_5.htm#SignToInt>
I think that only gets called when one of the operands is zero.

| You type: A=5:PRINT A
|
| Altair prints 0, should print 5
|
| You type FOR I=1 TO 10:PRINT I;:NEXT I
|
| Altair prints
|
| 0  0  0  0  0  0  0  0  0  ....
|
| Loop never ends since I is never incremented.
|
| Please help!  TIA

Hi,

I am selling an Original Complete MITS Altair 680 Computer with an expander
board, 2 memory boards and an I/O board in excellent condition.

The auction is here:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290577848590

There are lots of pictures and even a video of it running. There is no reserve.
Please contact me with any questions. Thanks.

-Glenn

This mainframe has the second transformer modification described in a Computer
Notes article. The buyer should be careful that the spacers used to assemble the
boards are long enough so a board back does not touch the mainboard crystal.

--- In altaircomputerclub@yahoogroups.com, "transient13" <transient13@...>
wrote:
>
> Hi,
>
> I am selling an Original Complete MITS Altair 680 Computer with an expander
board, 2 memory boards and an I/O board in excellent condition.
>
> The auction is here:
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290577848590
>
> There are lots of pictures and even a video of it running. There is no
reserve. Please contact me with any questions. Thanks.
>
> -Glenn
>

If anyone is located near San Diego and wants to help me test a new 8080 ICE in
their Altair, please contact me.  Thanks.  Bob Grieb

Bob's email address is bobgrieb ~at~ yahoo ~dot~ com

Steve
==================================

--- In altaircomputerclub@yahoogroups.com, "bobgrieb" <bobgrieb@...> wrote:
>
> If anyone is located near San Diego and wants to help me test a new 8080 ICE
in their Altair, please contact me.  Thanks.  Bob Grieb
>

Hi Bob,

I have been using your Z80ICE extensively in boot-strapping a new N8VEM-S100
system. It's been working perfectly and has enabled me to get the system running
on CP/M3 with banked RAM. Thanks for a great design.
I have an Altair and a ISMIA that I could use an 8080 ICE in. Please let me know
if I can help. Unfortunatly I live a little further away than San Diego ....
Australia.

Best regards
Leon Byles

--- In altaircomputerclub@yahoogroups.com, "bobgrieb" <bobgrieb@...> wrote:
>
> If anyone is located near San Diego and wants to help me test a new 8080 ICE
in their Altair, please contact me.  Thanks.  Bob Grieb
>

Hi All;
All I am looking for is the Instructions part of the manual, as I have the code
listing for the 8080 already
THANK YOU Marty

--- In altaircomputerclub@yahoogroups.com, "Marden P. Marshall" <mardy@...>
wrote:
>
> I have an original Tiny C manual and it's anything but tiny.  With all the
included listings it is probably somewhere around 500 pages.  It's on my list of
things to scan...
>
> Also, for those not familiar with it, Tiny C is not "C" or anything close to
it.
>
> -Mardy
>
> On Apr 23, 2011, at 11:48 AM, geistmarty wrote:
>
> > HI All;
> > Does anyone have a copy of the TINY C Manual ?? I would be glad to get a PDF
copied file...
> > THANK YOU Marty
> >
> >
>

Hi All;
I have another Altair 8800 for sale, it has an 8080 cpu board, 3 8K memory
boards, 2 4K memory boards, a non-Altair prom board and an Altair Disk
controller boards, the controller boards need work... It also comes with a Disk
Case, but without a Pertec Disk drive... I sent the Drive in for repair a year
and a half ago and have NOT gotten it back, nor will  they send me another one
either...
THANK YOU Marty

Hi,

I'm looking for the bottom/front bezel of the chassis. I've got one where the
front bezel has broken off. If anyone has a spare they would sell I'm
interested!

Thanks!

Cameron

I have a Grant Stockly CPU board that works perfectly in other systems but can't
use the cassette board in my system. I'd like to buy (or trade the Stockly board
for) a vintage 8080A CPU board. The timing may be sufficiently different to
allow it to work with my system. My Z-80 board works with the cassette board OK
so I know it's just a timing issue.

--- In altaircomputerclub@yahoogroups.com, "toml_12953" <tlake@...> wrote:
>
> I have a Grant Stockly CPU board that works perfectly in other systems but
can't use the cassette board in my system. I'd like to buy (or trade the Stockly
board for) a vintage 8080A CPU board. The timing may be sufficiently different
to allow it to work with my system. My Z-80 board works with the cassette board
OK so I know it's just a timing issue.
>
Would you be willing to send me the Board and I can compare it with Both my
Origional Altair 8080 CPU, and my Grant 8080 CPU Board, and see whether there is
/ are any differences between them...
THANK YOU Marty

Hi,

I'm from the United Kingdom and having a clearout of my attic as I am moving
house.

I have an an Altair 8800B computer with 256k RAM and 2 megaherzt 8080. I think
the transformer and that gigantic capacitor are missing but not had the lid off
for very many years.

Also have the Mits DataKeeper 2 x 5Mb 14 inch hard disk and Pertec controller.

Several 14 inch disks one with Microsoft Basic and one with EFAMOS multi-tasking
opsys on it.

My wife is pressing me to take it all to the dump but I don't want to do that if
someone wants it.

David

If anyone accepts David's offer, I have a lot of spare parts and documentation
for the Datakeeper hard drive (I'm assuming it's a Pertec D3422), such as power
supplies, HD controller boards (the controller is a separate unit the size of
the DCDD single 8" floppy cabinet), cables, heads, and other parts.  Not free,
but not expensive either.  Please contact me off-forum if interested.

FYI, the shipping weight of the drive alone will probably be around 100 pounds,
so shipping to the US will cost a bit.

Steve
alltare ~at~ yahoo ~dot~ com
=====================================

--- In altaircomputerclub@yahoogroups.com, "davidchester2" <david@...> wrote:
>
> Hi,
>
> I'm from the United Kingdom and having a clearout of my attic as I am moving
house.
>
> I have an an Altair 8800B computer with 256k RAM and 2 megaherzt 8080. I think
the transformer and that gigantic capacitor are missing but not had the lid off
for very many years.
>
> Also have the Mits DataKeeper 2 x 5Mb 14 inch hard disk and Pertec controller.
>
> Several 14 inch disks one with Microsoft Basic and one with EFAMOS
multi-tasking opsys on it.
>
> My wife is pressing me to take it all to the dump but I don't want to do that
if someone wants it.
>
> David
>

> I have an an Altair 8800B computer with 256k RAM and 2 megaherzt 8080. I think
the transformer and that gigantic capacitor are missing but not had the lid off
for very many years.


I should add, purely for amusement value, that I have had this computer system
from new!

It's original 1Mhz 8K RAM twin floppy incarnation was in 1977 when, with no boot
prom available yet, I had to key in the boot loader each morning in octal, using
the front panel toggle switches. It was then upgraded to 32K RAM and 2Mhz
processor and the 10Mb hard disk. Finally I went multitasking with the single
board 256K RAM (a bit "wow" in the 8K board days) thanks to a chap called Roger
Newman who looked after it for me after our original UK dealer folded.


David

On 7/7/2011 10:07 AM, davidchester2 wrote:
> Hi,
>
> I'm from the United Kingdom and having a clearout of my attic as I am moving
house.
>
> I have an an Altair 8800B computer with 256k RAM and 2 megaherzt 8080. I think
the transformer and that gigantic capacitor are missing but not had the lid off
for very many years.
>
> Also have the Mits DataKeeper 2 x 5Mb 14 inch hard disk and Pertec controller.
>
> Several 14 inch disks one with Microsoft Basic and one with EFAMOS
multi-tasking opsys on it.
>
> My wife is pressing me to take it all to the dump but I don't want to do that
if someone wants it.
>
> David

I didn't catch where in the UK this was located. I'm going to London next week
and would be interested in the CPU chassis but my wife would kill me if I
brought home the drive subsystem.

Steve

I have this computer with the CPU board and 8 K memory board that I am having
trouble getting it to work properly.  I don't have the original instruction
manual, but I was able to download a instruction manual for the MB-1 mother
board.  The downloaded instruction manual shows different terminating resistors
and it does not show a pot to adjust the voltage.If someone has  experience with
this board or a copy of the instruction manual with the pot to adjust the
voltage, I would like to hear from you. I would like to know if my circuit is
the latest circuit or if I need to upgrade the board  per the instruction manual
that I have.
Thanks for your consideration.

Jack

Hi Jack,

If you are using an Altair CPU board along with your 8K memory board, and that
is all you have in the system, then termination is not necessary at all.
Termination is only helpful when you want to run faster - for example with a 4
MHz Z80 CPU board.

I haven't looked at the MB-1 in quite a few years. But as I remember, the
original setup of the board worked just fine, though they did make a few
revisions over time.

What is the nature of the failure? Have you looked at the bus signals with a
scope?

Also, what are the resistor values on your board? - what is the pull-up value,
and what is the pull-down value?

The most common values are 360 ohms and 390 ohms, with a reference of 2.6V.

If you send me your email address, I will send you the manual for the Godbout
active terminator board. This manual has a pretty good explanation of the theory
of active terminators for the S-100 bus.

Cheers,
Martin


--- In altaircomputerclub@yahoogroups.com, "pipercub" <pipercub@...> wrote:
>
> I have this computer with the CPU board and 8 K memory board that I am having
trouble getting it to work properly.  I don't have the original instruction
manual, but I was able to download a instruction manual for the MB-1 mother
board.  The downloaded instruction manual shows different terminating resistors
and it does not show a pot to adjust the voltage.If someone has  experience with
this board or a copy of the instruction manual with the pot to adjust the
voltage, I would like to hear from you. I would like to know if my circuit is
the latest circuit or if I need to upgrade the board  per the instruction manual
that I have.
> Thanks for your consideration.
>
> Jack
>

Hi All;
I have sold this machine and Shipped it... THANK YOU Marty

--- In altaircomputerclub@yahoogroups.com, "geistmarty" <geistmarty@...> wrote:
>
> Hi All;
> I have another Altair 8800 for sale, it has an 8080 cpu board, 3 8K memory
boards, 2 4K memory boards, a non-Altair prom board and an Altair Disk
controller boards, the controller boards need work... It also comes with a Disk
Case, but without a Pertec Disk drive... I sent the Drive in for repair a year
and a half ago and have NOT gotten it back, nor will  they send me another one
either...
> THANK YOU Marty
>

I have put up for sale my Altair computer and 10 Megabyte hard disk with
controller.

The system has not been used for very many years and I've no idea whether or not
it still works. From memory I think it is 256K RAM, 2 Mhz 8080 CPU, 10MB 14 inch
Pertec datakeeper hard disk (5MB fixed + 5MB removable) with 6 removable disks
containing 2 x EFAMOS multi-tasking operating system, 2 x Microsoft Basic 5 and
2 x CP/M disks.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200636203829

Thanks

David

Hi All;
I have ONE Machine left, it is a Dual Disk Drive system with Rack mounting Bars
on the side... I assume very rare...
THANK YOU Marty
--- In altaircomputerclub@yahoogroups.com, billdeg@... wrote:
>
> Marty,
> How many more do you have ??
> Bill
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: geistmarty <geistmarty@...>
> To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
> Sent: Thu, Jul 28, 2011 8:54 pm
> Subject: [Altair Computer Club] Re: Altair 8800
>
>
> Hi All;
> I have sold this machine and Shipped it... THANK YOU Marty
>
> --- In altaircomputerclub@yahoogroups.com, "geistmarty" <geistmarty@> wrote:
> >
> > Hi All;
> > I have another Altair 8800 for sale, it has an 8080 cpu board, 3 8K memory
> boards, 2 4K memory boards, a non-Altair prom board and an Altair Disk
> controller boards, the controller boards need work... It also comes with a
Disk
> Case, but without a Pertec Disk drive... I sent the Drive in for repair a year
> and a half ago and have NOT gotten it back, nor will  they send me another one
> either...
> > THANK YOU Marty
> >
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>

Hi All;
I hope that I don't have to sell this one, but, as things keep getting worse and
I have to sell things to aford food and rent and the like, I may have to sell it
as well...
THANK YOU Marty

--- In altaircomputerclub@yahoogroups.com, billdeg@... wrote:
>
> So you're going to have none left?
>
>
>
>
>
> -----Original Message-----
> From: geistmarty <geistmarty@...>
> To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
> Sent: Sun, Jul 31, 2011 4:55 pm
> Subject: [Altair Computer Club] Re: Altair 8800
>
>
>
> Hi All;
> I have ONE Machine left, it is a Dual Disk Drive system with Rack mounting
Bars
> on the side... I assume very rare...
> THANK YOU Marty
> --- In altaircomputerclub@yahoogroups.com, billdeg@ wrote:
> >
> > Marty,
> > How many more do you have ??
> > Bill
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: geistmarty <geistmarty@>
> > To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
> > Sent: Thu, Jul 28, 2011 8:54 pm
> > Subject: [Altair Computer Club] Re: Altair 8800
> >
> >
> > Hi All;
> > I have sold this machine and Shipped it... THANK YOU Marty
> >
> > --- In altaircomputerclub@yahoogroups.com, "geistmarty" <geistmarty@> wrote:
> > >
> > > Hi All;
> > > I have another Altair 8800 for sale, it has an 8080 cpu board, 3 8K memory
> > boards, 2 4K memory boards, a non-Altair prom board and an Altair Disk
> > controller boards, the controller boards need work... It also comes with a
> Disk
> > Case, but without a Pertec Disk drive... I sent the Drive in for repair a
year
>
> > and a half ago and have NOT gotten it back, nor will  they send me another
one
>
> > either...
> > > THANK YOU Marty
> > >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>