[Simh] Altairs and PDPs

[ab31 at juno.com]

Sorry for the delay in writing again. I just moved myself and the
computer to another house. According to what I've read, the Altair is
usually considered to be the first personal computer. It was introduced
in the January 1975 issue of Popular Electronic magazine. It was a $400
kit which included 256 bytes of RAM and it could be programmed with
switches on the front panel. For serious work, people added extra RAM,
some kind of mass storage like paper tape or disk drive and a printing or
video terminal or maybe a keyboard and video display board. Microsoft
wrote its first BASIC for it. The bus was originally called the Altair
bus but other companies like IMSAI put the same bus in their computers
and they called it the S-100 bus. CP/M was available for the Altair. I
got the Altair simulator to explore the old versions of BASIC and to run
CP/M programs that I previously ran on a Xerox 820-II, an Ibex 7150, and
an Epson PX-8. Lots of popular programs can run on the Altair Simulator
such as Wordstar, DBASE II, SuperCalc 2, Infocom adventure games,
Microsoft BASIC, CBASIC, Turbo Pascal, and BDS C. The Altair simulator is
better than the real thing in some ways because it runs faster (on a
Pentium class computer), includes more RAM and bigger disk drives and can
optionally run a Z80 CPU instead of the 8080 so it can run more programs.
It includes a simulated paper tape punch and reader for running older
programs. I don't have the space to set up a lot of computers here so I
only set up my Windows 95 computer. Hopefully I can run emulators for any
other computers I'm interested in.

I don't know a lot about these PDP computers except that they were
minicomputers made by Digital Equipment Corp. I've heard that the PDP-8
and the PDP-11 were popular. I have an old book called "digital SMALL
COMPUTER HANDBOOK". It was written in 1967 by Digital Equipment
Corporation and it describes the PDP-8/I computer, peripherals and
software. It also has short descriptions of the PDP-9 and PDP-10.

Around 1977 I took a BASIC programming class in high school. At first
there was one minicomputer connected to two printing terminals. One was a
teletype (with paper tape punch and reader) and the other was a
DECwriter. They would get the BASIC language into the machine with a
DECtape machine. We saved our BASIC programs on paper tapes. I don't know
what this computer was. I think it was about the size of an IMSAI but
maybe it was some kind of DEC PDP computer. It must have been running
some kind of multitasking operating system to allow two users at a time.
Does this sound like something from DEC? Are there plenty of free
programs available for DEC minicomputers?

In my later programming classes we used Radio Shack TRS-80 Model 1
computers with Level II BASIC. The programs were saved on cassette tapes.
I remember writing a simple database program which could search any of
the fields for specific values. Now I have my own TRS-80 Model 1.
Somebody found it stored in a barn.

After getting out of school, I learned to use a Timex/Sinclair 1000, a
TI-99/4A (lots of experience with this one), a Xerox 820-II (using CP/M),
an PC/XT compatible computer, an Apple Macintosh 512, and a Commodore
Amiga 1000. I've also collected a few computers that I'm not in the habit
of using, like Atari 800XL and 520ST, Commodore 64 and 128, Apple II and
IIGS, and Radio Shack TRS-80 Model 1, 3,4 and Color Computer 2. The
biggest computer I have is a Wang PC which uses an 8086 CPU and super
large size expansion boards. It works now that I fixed a bad connection
on the 10 MB hard drive. Now I mainly use my Windows 95 computer which I
rescued from the trash. I enjoy programming in BASIC and am now trying to
write a good word processor in QuickBASIC. Sometimes I do little projects
in other languages like Pascal, C and assembly language. I've learned a
lot about about moving files around from one computer to another so maybe
I can help if somebody has questions about that.

Andy

>Well, I know what an Altair is, it's an S-100 based system, with if I 
>remember correctly an Intel 8080 CPU.  Personally I'm on the list 
>because of my interested in the PDP-10, PDP-11, and to a very, very 
>minor extent VAX (haven't seen a reason to try it as I prefer the 
>real thing) simulations.  I suspect that most people that are using 
>SIMH are using one of those three.
>
>		Zane


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