#TradeAndLaws
Extract : « I’m writing this letter to you to let you know that all is not wine and roses in the computer hobbyist field. There are snakes in our Eden. I am one of approximately forty SCCS Group Purchase victims. By sharing my tragic experience with you, perhaps I might be able to prevent a similar situation from re-occurring to others. [...] »
[author : David Jon Fylstra] #Networks
[author : Jef Raskin] #Networks
Extract : « The Pennywhistle 103, an originate modem by M & R enterprises in Sunnyvale, CA (which is a sunny place), is a good idea at a good price, with a few problems. For electronic whizzkids with a barrowful of test gear these problems will be easily surmounted, leaving them with a fine product. On the other hand a few details make this kit not a project for a beginner. There are some surprisingly inept features to the Pennywhistle, and it requires some rather fancy test equipment for alignment. But it is good value for the dollar, and is alone in its class for the moment.
The neologism “modem” stands for “modulator-demodulator”. [...] »
[author : Jef Raskin] #Audio
Extract : « Update to “Sour Notes on a Penny whistle”
This reviewer was gratified to learn that a lot of the problems that were discovered on the Pennywhistle in the accompanying review have also been discovered by M&R Enterprises. Better still, they have corrected many of the problems. This response to user feedback is most praiseworthy. However many of the early units are still out there and purchasers of them should write to the manufacturer [...] »
[author : Lichen Wang] #Listing #Assembly #Electronic
Extract : « VDM-1 from Processor Technology has two little bugs. Bug number one is when you access the screen memory frequently, you get a log of flickers on the screen. Bug number two does not happen very often, but when it happens, it may bomb your program. [...] »
[author : Phillip Schuman] #Listing #Assembly #HowItWorks #Interface
Extract : « For the new user of the SWTPC 6800 system, it seems easy to do I/O - just let MIKBUG* take care of it. But the question of how MIKBUG does I/O is a real mystery to the newcomer. I came up with that question and after searching through some manuals and schematics, finally got it all straight - - it’s magic. Well, not really, but it is helpful to learn how the system uses both the software (MIKBUG) and the hardware (PIA device) at the control interface port.
I will approach this subject in four parts; the addressing and selection requirements of the system, the PIA (MC6820 device) itself, SWTPC and MIKBUG usage of the PIA, and the software of MIKBUG and its inner workings. [...] »
[author : Kenneth S. Widelitz] #Association
Extract : « The Personal Communications Foundation (PCF) is no longer in its formational state. It has been lifted off the drawing board, is actually in operation and helping Hams, CBers and their attorneys.
The PCF is a non-profit, tax-exempt foundation organized expressly to serve as a central clearinghouse of information and research in the area of personal communications law. The PCF is the only organization of its kind because personal communications law is not yet formally recognized as a legal specialization. [...] »
[author : Joshua P. Gordon] #Languages
Extract : « I have some concepts which I would like to get some crosstalk on. Any response to these ideas from users of microcomputer systems in general, and those users with experience in the design and implementation of higher-level languages, would be most appreciated.
I am concerned about the process that is taking place regarding the implementation of languages such as BASIC, FORTRAN, and others for microprocessors. A great deal of time and energy is being spent in adapting these languages for smaller machines, and I believe that this time and energy is being misspent. [...] »
[author : Steve Witham] #BASIC #Programming
Extract : « Consider the way many Tiny BASIC interpreters work: the core of the program is written in machine language (ML); it interprets another program which is written in “Interpretive Language” (IL), and then the IL program interprets your BASIC program. This layered approach has been compared to an onion. [...] »
[author : APL Committee] #APL
Extract : « I have enclosed a copy of our APL Character Set poster which was displayed at the APL-Core booth at the National Computer Conference in Dallas.
This article has two parts. The first is a general description of our APL-Core project describing the results of our bench-mark tests in comparison to BASIC and to other APL's. The second article is to accompany the copy of the APL Character Set. It describes the method we used to implement the APL modified character set. [...] »
[author : H.T. Gordon] #Listing #Assembly #Programming
Extract : « Three recently-published programs (a debugger by Larry Fish in the Aug. ’77 Kilobaud, and relocators by Ralph Sherman in the April ’77 DDJ and by Jim Butterfield in the #4 77 Kim-1 user notes) include routines for calculating the number of bytes required by a 650X opcode. All use quite different logic, and none is richly documented or coded as an independent subroutine. This decoding operation is a wheel that has probably been reinvented many times (I did it as an early programming exercise long ago, as a not-very-efficient 51-byte subroutine). The following table shows the intricacy of the problem. It lists the 16 opcode types from X0 to XF, roughly in order of usage frequency in programs (650X programmers try to avoid using 3-byte codes!). Decoding execution time will be shorter if common codes are the earliest decoded, when this is compatible with an efficient bit-sifting routine. Types X0 and X9 are unusual in that the number of bytes is determined by X (the term X0 means an even number and X1 an odd number). Although the last 4 types are all illegal, coding errors may cause them; since they make up 60% of all illegal opcodes and are easy to sift out, this may be worth doing (but only the Butterfield program does it). [...] »
[author : Jim F. Butterfield] #Listing #Assembly #Diagnostic
Extract : « A recent algorithm by Knaizuk and Hartmann (IEEE Transactions on Computers, April 1977) outlines an ultra-fast RAM test.
The program below is based on this algorithm, but sacrifices testing efficiency to a small degree so as to achieve program compactness and simplicity. [...] »
[author : Steven Spence] #Listing #Assembly #Programming
[author : Martin D. Gray] #Listing #Assembly #Programming
[author : Morris G. Miller] #Listing #Assembly #Programming
[author : David J. Morgan] #Listing #Assembly #Game
[author : John Walker] #Listing #Assembly #Programming
Extract : « [...] I have developed an 8080 debug monitor (we must crawl before we run) which includes a complete interpretive trace with software breakpoints, trace within range for debugging subroutines and the ability to examine or change any machine register or memory location. The memory dump command permits memory to be examined in Hex, ASCII, or 8080 instruction format. The output of the trace is very easy to read (sample attached). [...] »
[author : Jef Raskin] #Listing #Basic #Mathematics