Re: [Simh] Odd Question on CP/M and sector sizes
Chris, A bit of Googling showed that the 137 byte physical sector size came from The Altair 88 disk controller. Search for 'Altair 88 dcdd disk controller 137¹ HTH Ton From: Simh on behalf of Chris Van Brederode Date: Friday 21 August 2015 18:45 To: Subject: [Simh] Odd Question on CP/M and sector sizes Hello, I'm working on coding my own 8080 emulator (as an exercise/hobby) and I've gotten to the point where I need to build BIOS for CP/M. I'm looking at using a SIMH based Altair emulator to build the CP/M for my system. I have a weird question though. All the documentation I can find on CP/M and floppies from that era point to a 128 byte sector size. But the source code in simh/Altair/altair_dsk.c (and also in the AltairZ80 source), the sector size is given as 137 bytes. Looking at this makes me cock my head like a dog. What is up with the extra 9 bytes? Where do they go when the fdc reads a 128 sector to memory for CP/M 3? Sorry if I sound ignorant, but I've actually tried to research this, but the only place I can find that mentions 137 byte sectors is the source file, and one post on this list that mentions that it is 137 bytes but doesn't say anything beyond that. Thanks for any help, Chris ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
Re: [Simh] off-topic basic translator
For a cookbook look at http://www.wherry.com/gadgets/retrocomputing/vax-simh.html It includes setting up TCP/IP. It is for Linux, but most of it is applicable to OS X too. At the end is how to install Basic. Just tried to install Basic on my OS X simh running VAX VMS 7.3. Installs fine. Ton van Overbeek > ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
Re: [Simh] Regarding "Cutler THE father of VMS" myth
Clem, Thanks for the reference to the Dijkstra paper. I had my electrical engineering education at the THE 1968-1974 and our introduction to programming class was taught by Dijkstra himself. Of course our exercises had to be programmed in Algol68 and run on the EL-X8 system described in the paper (entering programs on paper tape with a flexowriter). Interesting to read how ‘small’ the machine was in terms of memory and mass storage. The actual machine consisted of several cabinets. Apologies for the off-topic post. Ton van Overbeek From: Clem Cole Date: Sunday 8 March 2015 21:39 To: Sergey Oboguev Cc: "simh@trailing-edge.com" Subject: Re: [Simh] Regarding "Cutler THE father of VMS" myth On Sun, Mar 8, 2015 at 8:23 AM, Sergey Oboguev wrote: > If so, he may have a claim to inventing (a hint at) a microkernel concept. ;-) Dykstra invented the ukernel -- its the THE kernel: https://en.wikipedia.org/wiki/THE_multiprogramming_system The paper itself is http://uosis.mif.vu.lt/~liutauras/books/Dijkstra%20-%20The%20structure%20of% 20the%20THE%20multiprogramming%20system.pdf And all kernel hacker should read it some time. It where the idea of semaphores are defined and the idea of "up" and "down" - (aka P/V). Clem ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh ___ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh
