[author : Gary Gaugler] #Listing #Assembly #Simulation

Extract : «  If you enjoy your 6800 as much as I do, you rarely spend much time with thoughts of the 8080 or Z80. Nevertheless, there always seems to be some program which appears in a magazine that I would like to try out but can’t since it was written in 8080 code and won’t work on my 6800. Well now we can run 8080 code right on our 6800 machine via “emulation.”

Emulation is a technique whereby the code of the “target” (the 8080) is executed on a “host” machine (our 6800). The emulation process executes the target machine code via software written in the host’s language. So what we have is a way to run 8080 machine language programs via software in a 6800 system; we do not have to rush out and buy an 8080. All of this emulation capability is not free; the cost is loss of speed in emulated code. Code which is run on an emulator (at least for macroprocessors like we use) will be slower, much slower, than it would be if run on a machine for which it was intended. Since fast execution was not a prime consideration for emulating, just the program’s intended function, the slow execution time can be tolerated. [...]  »

[author : Aubrey Dahl] #History #Computer

Extract : «  The Univac II was a marvelous collection of 5,200 vacuum tubes, 18,000 crystal diodes, 184,000 magnetic cores, hundreds of feet of plumbing, and countless miles of wires. It’s a wonder that it worked at all; but work it did - for more than 18 years.

The year 1958 was not exactly a banner year in the course of human events, but it did usher in a computing classic when Sperry Rand first presented the Universal Automatic Computer Model II (Univac II) to the world.

It was not only one of the most powerful computers of that time, it was a veritable workhorse, persevering in varied environments on many different applications, and working on and on over the years far beyond the time of its expected obsolescence. [...]  »

[author : Fritz van der Wateren] #Lisp #Book

Extract : «  LISP is an interactive list processing language and very suitable for microprocessors. LISP is very easy to learn and has a very simple syntax. It is very easy to write recursive programs and functions, because the system will stack all returns and intermediate results. When you want to define, for instance, the function for N!, in LISP this would look like:

(DEF FAC (N)(COND ((EQ N 0) 1)(T (TIMES (N (FAC (MINUS N 1)))))))

“BASIC minded” people would find this an ugly notation, but in fact it is very well structured.

[...]

References

1. Berkeley, Edmund C., and Daniel B. Bobrow, The Programming Language LISP: Its Operation and Applications, MIT Press: Cambridge, MA, 1966.

2. Friedman, D.P., The Little LISPer, Science Research Associates: Palo Alto, CA, 1974.

3. Siklosky, Laurent, Let's Talk LISP, Prentice-Hall: Englewood Cliffs, NJ, 1976.

4. van der Poel, W.L., The Programming Languages LISP and TRAC, T.H. Delft: The Netherlands, 1972.

5. Waite, W.M., Implementing Software for Nonnumeric Applications, Prentice-Hall: Englewood Cliffs, NJ, 1972.

6. Weissman, Clark, LISP 1.5 Primer, Dickenson: Belmont, CA, 1976.  »

[author : John James] #Listing #Forth #Programming

Extract : «  Here are a couple short examples to illustrate programming in Forth.

Forth is a stack-oriented programming language which is also its own operating system. Typically the complete Forth system fits in only 6K bytes of code, which includes the Forth compiler, a run-time system including I/O drivers and virtual memory, a text editor, plus an assembler, which is (optionally) used for writing new I/O drivers or time-critical code which must run at full machine speed. Forth object code is very compact and the system is interactive, yet run-time speeds can be as little as 30 percent slower than machine code (100 percent on 8-bit micros). Typical hardware is 16K bytes and a CRT; for serious development work, a floppy or other random access mass storage for source programs is necessary. For more introductory info, see my article in the May, 1978 issue of Dr. Dobb’s.

The Forth system is like a root of a language which grows toward any application area for which it is used. Forth programs consist of short (usually one to five line) definitions of new operations, which then become part of the language. Each large application program is really a special-purpose language, greatly facilitating modification. Because object code is so compact, any general purpose operations (such as the examples below) can be added permanently to the language. Then they are automatically available to be used from the terminal as commands, or as instructions in other programs; and they are used in exactly the same way in either case. [...]  »

[author : Howard L. Nurse] #Electronic #Keyboard #Interface

Extract : «  If one reason you invested in a computer is to take advantage of word processing programs, a display restricted to upper case is as useful to you as a one octave piano is to a composer. Here is a simple method for converting the Health H-9 video terminal to display lower case alphabetic characters.

After studying the circuitry, I found it would be easy to modify the H-9 to include the missing characters. The keyboard on the H-9 would be difficult to convert, but Heath has provided a convenient parallel I/O connector on the rear panel of the terminal, through which an external keyboard having upper and lower case can communicate.

This article describes how you can add the integrated circuits and keyboard to an H-9 to make it a full upper/lower case terminal. [...]  »

[author : Joel Swank] #Listing #Assembly #Diagnostic

Extract : «  With a few dollars in parts and a small program, KIM can be used to test most SSI integrated circuits and some MSI devices. The best thing about this tester is that it is automatically programmable. You don’t sit over the data book trying to figure out what a device is supposed to do. You just plug in a known good device of the type under test, press the program key, and the tester is programmed to test that device.

This idea was published in the June ’78 Byte by Mark Thorson, but his implementation is a black box with hardwired logic and memory. I have moved all logic into software leaving some inverter/buffers, some wire jumpers, and the test socket as hardware.

The program communicates with the IC through a PIA (Peripheral Interface Adapter). [...]  »

[author : Titus Purdin] #Listing #Assembly #Storage #Diagnostic

Extract : «  Enclosed is a small utility program which I have found very helpful in designing and debugging disk files. [...]  »

[author : Phil Mork] #Electronic #Listing #Assembly #Diagnostic #Audio

Extract : «  [...] The vocal memory dump (VMD) program pronounces the octal value for each memory location in a block specified by the user. As such it is a useful tool for verifying memory contents (ever try to look at two listings at the same time?). It uses digitized speech waveforms in the form of a one bit sample every 155 [µ?] sec., which means both hardware and memory requirements are minimal. [...]  »