Warning: mysqli::__construct(): (HY000/1203): User howardkn already has more than 'max_user_connections' active connections in D:\Inetpub\vhosts\howardknight.net\al.howardknight.net\includes\artfuncs.php on line 21
Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: anton@mips.complang.tuwien.ac.at (Anton Ertl) Newsgroups: comp.arch Subject: Re: tiny COBOL, Article on new mainframe use Date: Mon, 02 Sep 2024 10:38:07 GMT Organization: Institut fuer Computersprachen, Technische Universitaet Wien Lines: 40 Message-ID: <2024Sep2.123807@mips.complang.tuwien.ac.at> References: <20240830183742.000065c5@yahoo.com> Injection-Date: Mon, 02 Sep 2024 13:50:30 +0200 (CEST) Injection-Info: dont-email.me; posting-host="03aad8c49d8689735d3cbe81745d6f2a"; logging-data="2985051"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19lEl6P3QQz0dUyl0Frq08z" Cancel-Lock: sha1:0OKp3YkgxhAVQNx5iPzBKWOgSBY= X-newsreader: xrn 10.11 Bytes: 3147 Terje Mathisen writes: >Thomas Koenig wrote: [Commodore 1541] >> And were extremely slow - around 300 bytes per second, comparable >> to a card reader. But fast loaders could improve on that up to 10 kB/s. > >They did that by reading every 1/2 sector, then reassembling after 2 >rotations, instead of having to wait a full rotation between every >sector read? No. The disk-access part of the disk drive was actually pretty cool, supporting variable data rate with a 6502. The variable data rate and group-code recording allowed getting 170KB on a single-sided single-density disk, while FM disk controllers typically got 85KB, and Wozniak got 140KB. I don't remember what was done about sector interleaving, but when you replaced the slow interface (see below) to the computer with a fast one (I have Prologic DOS), the drive was up to 28 times faster. The problem is in the data transfer between the drive (which had its own CPU) and the computer. They replaced the parallel IEEE-488 interface of the PET with a serial interface for cost reasons, and then they botched the serial transfer. There were some contributing factors, like the 6522 bug (the C64 had no 6522, though), and the desired compatibility with the VIC-20 (which then did not happen anyway: the Commodore 1540 (for the VIC-20) does not work unmodified with the C64). They probably could still have fixed the problem by giving some more love to the firmware for the computer-to-disk-drive interface; according to , the fastest serial fast-loaders were 15 times as fast as the serial routines in the firmware. I guess that, when the C64 was designed, disk drives were rare for computers with the price of the C64, so it did not seem that important to make that interface fast. - anton -- 'Anyone trying for "industrial quality" ISA should avoid undefined behavior.' Mitch Alsup,