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Something new to do for Altair floppy disk owners

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  • Mike Douglas
    The most common (if not the only) version of CP/M 2.2 for the Altair that can still be found among vintage computing hobbyists is the “Burcon” version
    Message 1 of 1 , Aug 14, 2014
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      The most common (if not the only) version of CP/M 2.2 for the Altair that can still be found among vintage computing hobbyists is the “Burcon” version released in 1980. Burcon was a computer store in the Houston area that sold Altair computers.

      From what I understand, the Burcon version of CP/M is common today, not because of widespread distribution in the early 1980's, but because most everyone who has presently has a copy of CP/M 2.2 for the Altair obtained it directly, or indirectly, from the same computer hobbyist within the last decade or so

      Lifeboat Associates, a large software distributor at the time, released CP/M 1.41 for the Altair in 1979 and released CP/M 2.2 for the Altair in 1981. Based on the people who originally had copies of Burcon CP/M, it is likely that Lifeboat CP/M 2.2 is a re-branding of Burcon CP/M 2.2, or just a minor revision. While copies of Lifeboat CP/M 1.41 are not hard to find today, I have yet to see a copy of Lifeboat CP/M 2.2. If anyone runs across it, I'd love the chance to archive it!

      The disk layout used in Burcon CP/M duplicates the disk layout used in Lifeboat CP/M 1.41. This means the disks, at least in terms of copying files, are interchangeable between the two versions of CP/M. However, the disk layout - specifically the sector skew - was not chosen wisely for optimum performance of most CP/M applications.

      After 34 years, I decided it was time to fix what was wrong with Burcon CP/M 2.2 and give the Altair a kick in the pants! CP/M version 2.2b is an update of Burcon CP/M 2.2 that provides substantial speed improvements along with a couple additional features:

      Compared to Burcon CP/M, version 2.2b loads CP/M programs in less than half the time. Any program with substantial disk I/O will run 20%-50% faster. By using track buffering to optimize disk access, no changes were required to the sector skew versus Burcon CP/M disks, so version 2.2b can interchangeably read and write Burcon (and Lifeboat CP/M 1.41) disks.

      Version 2.2b provides a full implementation of CP/M’s IOBYTE feature which allows re-direction of logical CP/M devices to a variety of physical devices. This allows use of serial ports in addition to just the first 2SIO port and allows programs like Kermit, which requires IOBYTE, to run properly.

      To better support a Teletype as the console, version 2.2b automatically transmits a null after C/R when it detects a Teletype as the console during cold boot.

      It's a fun exercise to spend some time using Burcon CP/M 2.2, then switch to the updated version 2.2b and perform similar operations. The speed improvement is immediately noticeable. Your old Altair will seem like a fast new machine!

      Updating to Version 2.2b:

      Files related to CP/M 2.2 version B are in the "Altair CPM 2.2 Version B" subfolder of the "Altair (Burcon) CPM 2.2" folder.

      Installing or updating to CP/M version 2.2b is as simple as running MOVCPM8 followed by SYSGEN on an existing Burcon CP/M disk. If needed, a copy of SYSGEN is present in the Version B folder. See the "PCGET and PCPUT" folder for an Altair CP/M file transfer utility if needed.

      Additional programs in the Version B folder include a fast format utility (AFORMAT) and a fast disk copy utility (ACOPY) both written by Martin Eberhard. If you have FORMAT already present on your CP/M disk, you’ll want to replace it with AFORMAT as FORMAT has a minor bug that is magnified by version 2.2b, and AFORMAT is dramatically faster!

      Finally, a complete disk image (cpm22b.dsk) can be written using the PC2Flop utility (see the “Disk Image Transfer Utilties” folder. This image is configured for just 24K of RAM, so it should run on most any machine. You can then immediately run MOVCPM8 and SYSGEN to size CP/M 2.2b for your machine.

      Feel free to contact me with any questions!


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