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Original Macintosh Architecture Questions
by John Heritage 26 Jun '21

26 Jun '21

Hey folks -- Two items I'm curious about on the classic (and very original) Apple Macs.. 1. Mac (128kb ,512kb, etc) audio -- was there a custom or off the shelf sound chip for the audio on the original Mac? and was it 1 channel / and was it a custom chip by Apple? (how did it achieve speech synthesis in 1984) 2. The Macintosh Classic released in 1990 "was about 25% faster than the original Macs". This is in line with the Atari ST often being quoted as faster than a Mac when emulating a Mac via Magic Sac or similar. What changed in the architecture to make the Mac Classic (or an ST in emulation) faster than the original Mac? Was it faster memory that gave more availability for CPU usage? were only certain instructions sped up or was everything faster? Thanks!

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free stuff update
by Bill Degnan 25 Jun '21

25 Jun '21

https://www.kennettclassic.com/freestuff/ A few changes to the free stuff pile. Bill

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IEEE Spectrum: A PDP-8 makes a stylish addition to any home.
by Jeffrey Jonas 25 Jun '21

25 Jun '21

old news to us: https://spectrum.ieee.org/geek-life/hands-on/put-the-classic-pdp8-minicompu… Put the Classic PDP-8 Minicomputer on Your Shelf This Raspberry Pi–powered replica runs all the original PDP-8 software with enough cycles left to double as a media server. A PDP-8 makes a stylish addition to any home.

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Homebrew Computer Systems from Bob the donor
by Herb Johnson 25 Jun '21

25 Jun '21

Thanks for the back story about "Bernie S paid a visit" and the computer brought to the repair workshop "for Dmitry". So now that Dmitry has the back story, what's his/her plan for the remains? It would be nice from my view, if the computer remains could at least be physically reassembled to preserve some kind of history of that kind of construction. I don't think they can be made to work again, nor need they be in my opinion. (The Apple II clone is in another, later category but of the same kind.) But if Dmitry plans to just use the parts - which is of course up to them - then it's good to have preserved the narrative and technical history at least. I have a Web site for the stories and tech I preserve. For those who think this looks awful, well, this is how we built microprocessor computers at home. In the earliest days, there just weren't' any "computers" to build, just micro processors or at best $1000 development systems or $300 development boards. In the mid-1970's, you could buy a *new car* for a few thousand dollars; $300 was an apartment's monthly rent. And, there weren't many single-chip functions - like "a floppy controller chip". So one board equaled one function. And floppy drives were expensive too. Most early computers used either paper-tape, or cassettes. And that worked fine for the small programs in use. These weren't built for looks, they were built for function. Many of the builders were learning as they went. Some were designing as they went, and as new chips became available. Getting them to work was an achievement. So, in my experience from the era: the 6502 computer when built, was an example of the time, early and certainly not common. The Apple II add-ons, was a thing that some people did, building on an available computer board. Using an 8-track drive for data is kinda scary, but it's a plausible extension of cassette data drives. But, once microcomputers got relatively affordable or were "cloned" cheaply, these hand-wired computers got shelved. When the technology advanced, these became less and less "functionally useful". So most were parted out or dumped. Since they were all unique, and didn't have that mass-produced designer look; they became cryptic, unfamiliar. That's why you don't see them much today, 40 years later. And time passed, is why work like this needs an explanation. Regards, Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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Old Heathkits Never Die, They Just Get Restored
by Herb Johnson 24 Jun '21

24 Jun '21

This isn't just "a Heathkit". This is a Heatkit analog computer, one of a number of analog computer models produced by Heath. And it is a nicely done article, describing a restoration and now-unfamiliar components; vacuum tubes not the least of them. The subject functionality itself is unfamiliar. Now 21st century persons have been introduced to this 1960's tech and mid-century analog computers. There's a companion brief article on earlier large scale analog computers and their role in engineering and science. So persons interested in these subjects should review this article. Regards, Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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Old Heathkits Never Die, They Just Get Restored
by Christian Liendo 24 Jun '21

24 Jun '21

I enjoyed the article, i figured others might enjoy as well. https://www.nutsvolts.com/magazine/article/May2016_Heathkit_Restoration

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Original Macintosh Architecture Questions
by Herb Johnson 24 Jun '21

24 Jun '21

> Mike Willegal > I agree that the original Macintosh (128K) is very painful to use, especially if you try to use it with only the single floppy drive that came with it. Saying it has a poor system design without understanding the design constraints that the developers were faced with, is doing them a disservice. > Once more memory and a SCSI hard drive were added with the release of the Macintosh Plus, the user experience with the same basic hardware and software system was transformed into a very positive one proving the basic system design was good. I'm not sure if I disagree with Mike or not. He makes a point about early technology being a performance dog, which got fixed with later tech. He makes a point about "quality of system design" that's some mix of hardware performance and usability of software. And points about a company's development situation among a mix of products available and technology behind and ahead. I think he's overly critical of the 128K at its point in time. In my view, the 128K Mac and its operating environment, gave a class of potential (not actual yet) computer users an entirely different way to run programs, and to run all programs in a consistent *graphical* fashion. The physical package itself was attractive and portable (by standards of the time). And it came from a computer company with a good reputation and history. I think the audience that 1984 computer found, weren't worried about "performance" and did not find the 128K Mac "painful to use". They could not look ahead to change their expectations; they were not users of command-line computers with multiple drives (floppy or hard). Myself, I was working near a doctor's office at a time. They were using 128K and 512K Macs, and getting office work DONE. I'm pretty sure they weren't reading technical manuals, or had run CP/M systems beforehand. Those Macs enabled their productivity. Sounds like a home run to me. But I'm not sure what Mike was responding to, because the discussion thread shifted to SGI equipment for a long stretch. So pardon me if I'm a bit confused. Regards, Herb Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net

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Original Macintosh Architecture Questions
by Herb Johnson 24 Jun '21

24 Jun '21

Will the next person to post about SGI equipment, *please* consider changing the subject line to something appropriate? It's a simple courtesy to not "hijack a thread" with a new subject. Thank you. Regards, Herb

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Re: Original Macintosh Architecture Questions
by MikeWillegal 24 Jun '21

24 Jun '21

I agree that the original Macintosh (128K) is very painful to use, especially if you try to use it with only the single floppy drive that came with it. Saying it has a poor system design without understanding the design constraints that the developers were faced with, is doing them a disservice. 1) Hardware cost was critical. Apple already had the Lisa. The Macintosh was intended to get the Lisa GUI to an affordable price point that would encourage mass market adoption. The cost goal... a) Limited the system to 128K of DRAM and 64K of ROM. b) Floppy drive only for mass storage. 2) The designers were challenged with implementing a fairly complex GUI a) To make the feature set fit within the available memory, the designers had to implement a paging system to pull system features off of floppy as needed. This degraded performance a great deal, but the only other design choice they had was to reduce the feature set. Once more memory and a SCSI hard drive were added with the release of the Macintosh Plus, the user experience with the same basic hardware and software system was transformed into a very positive one proving the basic system design was good. My opinion is that marketing pressures required that the system to be released before the technology for a high performance system of this type was really affordable. Though significantly enhanced over the years, the same basic architecture lived on until the release of OS/X in 2001, which is not a bad run for a system which was originally designed to work on hardware with such significant limitations. regards, Mike Willegal

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Museum Report 2021-06-23
by Jeffrey Brace 24 Jun '21

24 Jun '21

About a dozen visitors today, which means that summer visitors have begun. Normally there are very few visitors on Wednesdays, but in the summer we get a decent number. The first two visitors were an older couple and their grandson from Florida. He specified to his grandfather that at the top of his list of things to do was to come visit our museum. He was a finance major, but had learned to program in the "R programming language". I had never heard of this, but in any case I explained to him how computers worked, and the history of computers. He was fascinated. He stayed about 2 hours and I had him try some BASIC programming. He loved it! There was another visitor who was Bulgarian and recognized the Apple 2 clone that we had in the museum. She actually knew what it was and where it was manufactured and some history. Her son tried out some BASIC programming on it and stayed for over an hour. There were some other visitors who spent about 40 minutes there, but it became hard to help everyone with three groups of highly interested people. There were 3 last minute visitors, but the girl really liked that most of our computers were hands on because many museums don't allow that. She really enjoyed using them. Overall a good day at the museum. ========================================= Jeff Brace Vice President & Board Member Vintage Computer Festival East Show-runner Vintage Computer Federation is a 501c3 charity http://www.vcfed.org/ jeffrey(a)vcfed.org

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